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VAN NOSTRAND'S

ECLECTIC

ENGINEERING MAGAZINE.

VOLUME VI.

J-J±.l<TTJJi.JEl^r — JUISTE,

1872.

NEW YORK: r>. VAN NOSTRAND, PUBLISHER,

23 Mueeay Steeet and 27 Waeken Street (up states).

1872.

3P?6? /

f\

.V3

CONTENTS.

VOL. VI.

Page

Absorption of moisture 127

Action of a Propeller 624

Adulterated cement 336

Alloys 666

American Institute of Mining

Engineers 103, 328, 442

Russia Sheet Iron 215

Society of Civil Engineers 329

Antimony, extraction of 464

Arches, stability of 565

Arches, strains on 173

Architecture for Engineers .... 241

of Second Empire 587

Artillery, Fi eld 169, 604

heavy 77

light 77

Artesian well, Boston 106

Art, nitrogen in 163

Of spoiling public build- ings 66

Asbestos piston-rod packing. . . 260

Asiatic telegraph 224

Asphalt roads in Paris 112

Atlantic and Pacific Kail way. . 219

Atmosphere, solar 337

Australian telegraph 391

Babbage C, Philosopher 275

Balloon, Navigable 640

Basin at Chatham Dock- Yard . 363

Behavior of cements 157

Bessemer converter, gases from 38

Bessemer steel 212

Bessemer steel, pig metal for. . 554

Blast furnace econonvy 230

Blast furnaces in Germany 660

Boiler incrustation, prevention

of 440

Boiler plates, efficiency of Ill

Book Notices :

Aldis," T. S. Text-book

of geometry 558

Baird, Spencer F. Annual record of science and in- dustry 666

Beans, E. W., C.E. Trea- tise on railway curves . . 666 Bell, I. Lowthian. The chemical phenomena of

iron smelting 665

Chambers, G. F. Packet

of astronomical plates. . . 334 Cotterill, J. H. Notes on

steam engine 333

Donaldson, Wm Tables

for plate layers 558

Edgar, J. H". Note book

on geometry 221, 447

Fletcher, Banister. Dilap- idations 665

Forrest, J. Minutes of the proceedings of the Insti- tution of Civil Engineers 109

Page Book Notices:

Grover, J. W. Estimates and diagrams of railway bridges 558

Gruner, M. S. Manufac- ture of steel 446

Hanna, J. S. Complete ready reckoner 109

Harris, S. Rudimentary magnetism 447

HaskolL W. D, C. E. Atchley's estimate aud price book ... 665

Huxley, Roscoe and Stew- art. Science Primers 664

Jamin, M. J. Petite traite de physique 222

Johnson, M. H. Flint 222

Jones, B. Royal Institu- tion, its founders, and its professors 334

Lyle, M. E. S. What are the stars 331

Maxton, J. Workman's manual of engineering drawing 109

Maxwell, J. S. Theorv of heat 334

Maxwell, J. Clerk. Theory of heat 447

Mulcaster, J. W. Elemen- tary on statistics 109

Newdegate, A. S. Scales for comparison of British metric weights and measures 334

Nystrom, J. W. Pocket- book of mechanics and engineering 559

Page, David, LL. D. Ad- vanced text-book of Ge- ology 665

Palliser, J. W. Complete course of problems in practical plane geometry 189

Palliser, J. W. Problems in geometry 222

Phin, J. Plain directions for the construction and erection of lightning; rods 559

Poole, Francis. Queen Charlotte Islands 446

Pritchard, G. S. Note- book on geometry 221, 447

Proctor, R. A. Lessons in elementary astronomy . . 334

Profs. Schellen, Roscoe and Huggins. Spectrum An- alysis explained 666

Richter, T. H. Platner's manual of blow-pipe analysis 107

Pag. Book Notices :

Slack, H. J. Marvels of

pond life ... . 222

Smith, J. H. Elementary

statistics 447

Tarn, W. Practical geom- etry 333

Tarn, E. W. Practical geometry for the archi- tect, engineer, surveyor,

and mechanic . 558

Trautwine, J. C. ; Civil en- gineer's pocket-book 109

Timbs, J. Text-book of

facta, 1872 559

Todhunter, J. Researches in the calculus of varia- tions 334

Whipple, S. An elemen- taryand practical treatise

on bridge building

Wilson, J. Treatise on

English punctuation 109

Wilson, G. Inorganic chem- istry 222

Young, W. Architectural

Studies 222

Boring of mining shafts 333

Boston artesian well 106

Brake, dynamometer 94

Breech-loaders for the Russian

army 280

Bridge at Carondelet 221

Bridge, Cylinders for » 237

Draw-span of 557

East River 448

Fall of 224

Kansas City » 219

Lake Champlain .. 221

Rock Island 221

St. Joseph, stone for .. 221

St. Louis 445

British Iran Trade 660

Bridge at Omaha » 664

Bridges of London 249

British CoaFCommissioners' re- port 447

Broad and narrow gauge rail- ways 51, 525

Buildings, art of spoiling 66

Canadian Pacific railway 544

Petroleum 74

Canal boats, propulsion of. ... 229

Cavour 380

North Sea 40

Ship 156

Suez 559

Tehuantepec 129

Carbonized sewage 504

Car, propulsion by pneumatic

power 263

Castings, steel 41

CONTENTS.

Page

Cast iron, porosity of 13-1

Steel, homogeneous 554

Causes of earthquakes 537, 577

Cement, adulterated 336

Behavior of 157

Strength of 438

Manufacture in India 204

Channel ferry 510

Tunnel 444

Chemical phenomena of iron

smelting 407

China to England 223

Cinnabar mines 224

Circuit system 70

Civil Engineers, Society of . . . . 214

Classification of steel 143

Coal dust, utilization of 261

Cobalt, deposition of. 336

Coming transit of Venus 514

Compass, compensation on iron

ships 247, 371

Compressed air, living force of. 274

Air engine 496,573

Concrete mixing mill 136

Building 281

Condition of the Pacific rail- ways 219

Conjunction of cements and

metals 157

Controversy, gauge 142

Cottage building in Norway . . 591

Crucible for melting metals . . . 559

Current observations 532

Curves in wagon roads 78

Curved smoke stack 208

Structures, stresses on 307

Cylinders for the Albert bridge 237

Danks' puddling furnace 104

Rotary puddler, test of. . . 443 Decade of steam road rolling in

Paris 298

Decimal system in Austria 112

Degree, measurement of 656

Density of water 350

Dephosphorizing iron ore. .329, 378 Derbyshire Institute of Engi- neers 329

Desiccation of wood 283

Detroit river tunnel 557

Discoverv of a drawbridge near

Windsor 448

Distribution of water in India. 422

Douglass, Major David Bates. . 1 Drawbridge near Windsor,

discovery of 448

Draw-span of the Davenport

bridge 557

Durability of framed timbers of

buildings 559

Of differeut kinds of wood. 335

Earth's gravity 223

Earthquakes, causes of 537, 577

Earthwork, formula for. 325

East River bridge 448

Economy, blast furnace 230

Edinburgh Engineers' Society. 103

EfHciencv of boiler plates Ill

Efflux of elastic fluids 513

Electro deposition of Nickel and

Cobalt 336

Electro-Plating in France 335

Ellis bi-sulphide of carbon, en- gine 441

Emerald mines of Muzo 506

Enamel for metals 223

Engine, atmospheric 140

Compressed air 496

Cylinders, marine 425

Engines in the British navy... 470

Page

Engines, Steam, lubrication of. 223

Vertical 593

Engineering, Indian 47

Society 103

Engineers^Institute of 214

Mining 214

English Channel, proposition to

tunnel under 560

Estimates, graphical 335

Euphrates valley railway 35

European products in Japan. . . 32 European measurement of a de- gree 656

Examination on inertia and

momentum 81

Exhaustion for underground

purposes 214

Expenditure, locomotive work- ing. 145

Experimental steam boiler ex- plosions 473

Trip of steam engine Ravee 252 Experiments on durability of

timber 335

On steam boilers 69

On the strength of ma- terials 385

Exploration, Roman 146

Explorations, deep sea 224

Explosion, petroleum . , 156

Explosions, experimental steam

boiler 473

Explosive compounds 386

Extraction of metallic anti- mony 464

Fairlie svstem 357

Pall of a* bridge 224

Feed water heating 175

Field artillery 169, 604

Filtrations, intermittent 112

Filtering process 224

Fire bricks, notes on 6

Fire-proof floors 353

Flax, New Zealand 584

Floors, fire-proof 353

Fluids, efflux of 513

Formula for earthworks 325, 428

Fortifications, pre-historic 364

Four-wheeled locomotives 326

Fracture of railway axles 443

Framed timbers, durability of. 559

Friction in steam engines 379

Fundamental principle of the

action of a propeller 624

Gas companv, Yokohama and

Tokio...." 560

Illuminating 398

Manufacture, private 362

Gases from Bessemer converter 38

Gauge controversy 142

Gauges of rails 139

German and French steel 660

Girders, strains on 19, 311

Glasgow, water supply of 462

Globe engirdled 168

Glycerine, use of 83

Gold standard in Germany 153

Gothic church restoration 96

Gradienter 323, 512

Granite works of the ancients. . 560

Graphical estimates 84, 335

Gun-cotton, report of 479

Gravitation, Whelplev's theory

of : *. 172

Gunpowder, manufacture of. . . 373

Hardening steel cutting took. . 666

Heating feed water 175

Heat, radiant 113

Solar 499

Page Heat Transmitted by incandes- cent spherical bodies 449

Heav)' and light artillery 77

Henderson's Process 657

Hirsch's screw propeller 110

Homogeneous cast steel 554

Hoosac tunnel 558

Hot blast, theory of 631

Housatonic river bridge 444

Hydraulic ram 464

Hydraulics, Science of 198

Ice-making in the Tropics 447

Illuminating gas 398

Improvements in iron rails 30

IntheTiber. 110

Impurities of wool 162

Incandescent radiators 225

Indian engineering 47

Rivers 47

India-rubber, manufacture of. 42 India storage and distribution

in 422

Indicator 94

Inertia, examination of 81

Institution of Civil Engineers. 553 Institute of Mechanical En- gineers 102, 441

Of Mining Engineers 214

Intermittent filtration 112

Iron barges for canal transit. . . 448

Casting 448

Electrotype. . ; 14

Interest 216

Land of New Zealand 336

Manufacture in France .... 104

Metallurgy of 116

Ore, dephosphorizing. .... 378

Rails, improvements in. . . 30

Smelting 407, 657

Soft.... _ 41

Surfaces, preservation of. . 245

Trade of Great Britain. .105, 660

Irrigation vs. Disinfectants ... 17

Isthmus of Suez 32

Joints, strength and propor- tions of 441

Kansas City bridge 219

King's College Engineering So- ciety 554

Lake Champlain bridge 221

Land as a purifier of sewage.. . 184

Leith Engineers' Society 103

Levant telegraphs 372

Lime process for sewage 595

Living force of compressed air. 274

Locomotive, performance of. . . 556

Working expenditure 145

Weight of 154

Four-wheeled 326

Long struts, strength of 434

Lubrication of steam engines. . 223 McNair's invert permanent

way 330

Magnetic storms 355

Manufacture of gunpowder du- ring the siege of Paris. . 373

Of india-rubber 42

Of iron in India 369

Of steel rails 435

Manufacture of trinkets 610

Marine engine cylinders in the

navy 425

Engines in the British

navy 470

Massachusetts Society of Arts 659

Materials, new building 508

Strength of 339, 385

Mechanical Engineers, Institu- tion of.'. 102

CONTENTS.

Page Mechanical Engineering, pro- gress in 365

Metallic bismuth 395

Metallurgy of iron 116

Metals in conjunction 157

Meters, water ... . 342

Mill for mixing concrete 136

Mines, Cinnabar 224

Mining Engineers, Institute of 103

Shafts, boring of 333

Modern cannon powder 289

Moisture, absorption of 127

Momentum, examination of. . . 81

Mont Cenis tunnel 62

Narrow gauge vs. wide gauge.

51, 515, 570

Nature, nitrogen in 163

Navigable balloon 640

Navy of the future 429

New cement 335

New Prussian rifle 609

Zealand flax 584

Nickel mines 576

Nickel, deposition of 336

Nitrogen in nature and art ... . 163

North Sea canal 40

Notation, Sec-system of 75

Notes from Germany 259

On lire bricks 6

Observations, current 532

Operating railway by telegraph 219

Pacific railways, condition of. . 219

Paper-making in Japan 287

Paris Society of Civil Engineers 661

Paris, public works of 606

Passenger trains, speed of 218

Patent fuel 160

Performance of a locomotive. . . 556

Petroleum, Canadian 74

Explosion 156

Philadelphia & Reading rail- road 331

Phosphate sewage process 396

Pig metal for Bessemer steel. . 554

Pneumatic despatch tubes. ... 70

Transmission 465

Polytechnic club. 441

Porosity of cast iron 134

Pre-historic fortifications 364

Preservation of iron surfaces . . 245

Of wood from decay 481

Prevention of boiler incrusta- tion 440

Private gas manufacture 362

Problem of the rafters 233

Products, European, in Japan. . 32

Propeller, action of 624

Propeller, turbine 454

Proposition to tunnel under

English Channel 560

Propulsion of canal boats 229

Prussian rifle 609

Public works of Paris 309, 660

Puddling furnace, Danks' 104

Radiant heat transmitted by incandescent spherical bodies

113, 449 Radiators, temperature trans- mitted by 225

Rafters, problem of 233

Rails, weight of 123

Railroad bridge at St. Joseph. . 129

Philadelphia & Reading. . . 331

Railroads in Peru 589

Railway, Atlantic & Pacific ... 219

Axles, fracture of 443

Bridge at Albany 444

Bridge at Omaha 664

Bridges in Canada 664

Page

Railway, Canadian Pacific... 544

Earthwork, estimates for . 84

Enterprise 444

Euphrates Valley 35

Interests 6C3

St. Louis, Lawreno &

Denver 219

Switch 663

Railways, broad gauge 51

In Asia Minor 331

In Australia 105

In Kansas 331

In Turkey ... 43, 556

Narrow gauge 51, 570, 663

Of the world 444

Ram, Hydraulic 464

Ransome's patent stone 158

Raw material for Bessemer

steel 212

Recent progress in mechanical

engineering 365

Renaissance, church restora- tion 96

Rifle, new Prussian 609

Rigid arches, stresses on 307

Rivers, Indian 47

Of France 98

Road-rolling in Paris 298

Rock Island bridge 221

Rolling-mills of Pittsburg .... 443 Rolling stock of the Pennsyl- vania railroad 302

Roman exploration 146

Rosendale viaduct 664

Royal Institute of British Arch- itects 660

Royal Society 661

Russian progress in Asia 128

Sassafras oil 384

Screw propeller, Hirsch's 110

Sec-system of notation 75

Seine 599

Sewage irrigation 33

As a fertilizer of land 184

Treatment and utilization

of 494, 595

Sheet-iron 215

Ship canal 156

Ships, unarmored 360

Smoke-stack 218

Society of Civil Engineers 214

Society of Practical Engineer- ing 214

Softening of water by the use

of lime-water 560

Soft iron and steel castings. . . . 41

Solar atmosphere , 337

Heat 499

Radiation, temperature

produced by 91, 561

Soundings in the Baltic 336

Speed of passenger trains in

England 218

Sponge -paper 248

Spur-wheels, strength of 208

Stability of arches 565

Standard vs. narrow gauge . . . 570

Staining ivory 666

Staining marble 352

Steam boiler explosions 223

Boilers, experiments on. . . 69

Brake 219

Engine cylinders 271

Engine Ravee 252

Elasticity of 43

Temperature of 43

Theory of 643

Tramway cars 415

Steel castings 14

Page

Steel, Classification of 143

Manufacture in Birming- ham 256

Rails, manufacture of 435

Tools 666

Process, Henderson's 657

Steeled wheels 330

St. Gothard tunnel 220

St. Louis bridge 445

Lawrence & Denver rail- way 219

Stone for St. Joseph bridge. . . 221

Ransome's patent 158

Stones, velocity of 50

Scorage of water in India Azt

Storms, magnetic 355

Sti ains on arches 173

On straight girders and

trusses 19, 311

Strength of cement 430

Of long struts 434

Of materials 339

And proportions of riveted

joints 441

Of spur-wheels 208

Sub-marine boats 315

Suez canal 445, 559

Sun, temperature of 561

Superstructure of the St. Louis

bridge 332

Sutro tunnel 333

Swiss method of driving piles 269 Tehuantepec railroad and ship

canal 129

Telegraph, Asiatic 2'J4

Australian 394

West Indian 224

Telegraphy in France 564

Temperature and elasticity of

steam 43

Produced by solar radia- tion 91

Temperature of the surface of

the sun 561

Temperatures transmitted by inclined incandescent radia- tors 225

Temple of Diana at Ephesus. . 608 Testing steel by the micro- scope 224

Testing value of Unguents . . . 620

Test of Danks' rotary puddler.. 443

The Seine 599

Theory of the steam engine. . . 643

Theory of gravitation 172

Of the atmospheric engine. 140

Of the hot blast 545, 631

Of the steam engine 643

Tiber improvements 110

Timber, durability of 335

Tin trade ". 151

Tokio Gas Company 56Q

Torpedo boat 445

Traction engines 214

Tramway at Chatham 352

Structure of 177

Transmission, pneumatic 465

Treatment and utilization of

sewage 494, 595

Trinkets, manufacture of . . . . 610

Mersey 664

Trusses, strains on 19, 311

Tunnel, Channel 444

Detroit river 557

Hoosac 558

Mont Cenis 62

St. Gothard 220

Sutro 333

Mersev 664

CONTESTS.

Pago

Turbine propeller 454

Turkey, railways in 43, 556

Unarmoreil ships 360

Unguents, testing value of . . . 620

Use of glycerine in paper 83

Utilization of coal dust 2 >1

Of sewage 494. 595

Vegetable parchment 224

Velocity of meteoric stones.. 50 Ventilation of manufactories. . . 390 Venus, coming transit of 514

Pace

Vertical engines for the navy. . 593

Wagon roads, curves in 78

War Department report of gun

cotton 470

Water, density of 350

Water meters 312

Softening of 560

Supply of Glasgow 462

Weather signals of U. S. signal

service Ill

West Indian telegraphs 224

Pajr.

Weight of rails 123

Wharton railway switch 663

Whelplev's theory of gravita- tion..". 172

Wood, desiccation of 283

Durability of 335

Preservation of 481

Wool, impurities of 162

Working railway inclines 106

Xylonite 112

Yokohama (las Company 560

^-J <4— ^JL

2frr**.'&-in^.

VAN NOST RAND'S

ECLECTIC

EMIN.EEEING MAGAZINE,

M XXXVIL- JANUARY, 1872.— VOL. YL

MAJOE DAVID BATES DOUGLASS.

A Biographical Sketch.*

David Bates Douglass, son of Natha- niel and Sarah Bates Douglass, was born at Pompton, New Jersey, March 21, 1790.

His early education was carefully and ably superintended by his mother until he was prepared to enter Yale College, from which he graduated with high hon- ors in 1813.

From Yale College young Douglass went directly to the Military Academy at West Point, and soon entered the military service of the United States as an officer of the Engineer Corps. In 1814 he was detailed with his command in the North- western campaign of that year. He per- formed brilliant service during the siege of Fort Erie, for which he received the commendation of General Gaines, and was further rewarded by promotion to a captain by brevet.

About 1816, Captain Douglass received the appointment of Assistant Professor of Natural Philosophy in the Military Acad- emy, and the succeeding 15 years were spent by him in active official duties at West Point and in civil engineering-.

Til •

In the practice of this latter profession, he made, in 1826, surveys and estimates for a csnal from Conneaut Late to Lake Erie. The same year he made surveys for the location of the Upper Delaware canal. A revision of the surveys of the Sandy and Beaver canal, of Ohio, followed by an

• Lives and Works of Civil and Military Engineers of Amer- ica, by Chas B. Stuart, C. E. New York : D. Van NostranJ.

Vol. VL— No. 1—1

examination and survey of the vicinity of Philadelphia, to establish the terminus of the Pennsylvania Railroad, were profes- sional services performed about the samo period.

In November, 1828, Major Douglass made an examination of the line of the Morris canal, of New Jersey, with refer- ence to the employment of inclined planes instead of locks. His subsequent report and plans led to a professional engage- ment in the service of the Company, and his resignation of his chair at the Military Academy. This occurred in 1831.

The inclined planes were soon brought into successful operation, and were justly regarded as an important engineering achievement.

In 1832 he entered the New York Uni- versity, its first Professor of Natural Philosophy; but finding his professorship to interfere with his engineering pursuits, he relinquished this position after one year's duty, but was borne on the roll of the institution as Professor of Civil En- gineering and Architecture, and during the year of 1836 and 1837 he delivered a course of 80 lectures on these subjects.

In 1833 he was called upon to survey the route for the Brooklyn and Jamaica Railroad on Long Island, which he com- pleted in the winter of that year.

An act was passed by the New York Legislature, February, 1833, authorizing surveys and estimates for supplying the citv of New York with water. Ininie-

VAN NOSTRAND'S ENGINEERING MAGAZINE.

diately after the passage of this Act, the Board of Water Commissioners appointed Major Douglass and Canvass White, en- gineers. But the professional duties of Mr. White in the State of New Jersey preventing him from making the exami- nation desrred by the commissioners, the whole duty devolved upon Major Doug- lass, who completed the preliminary sur- veys in November of that year, and made his report soon thereafter ; regarding which the commissioners, in their report of November, 1833, say:

" For a more particular and detailed description of the surveys, and other im- portant information on the subject, the commissioners beg leave to refer to the able and lucid report of the engineer, Major D. B. Douglass, hereunto annexed." In the report referred to, Major Douglass recommended the use of the Croton river and its tributaries to be conveyed to the city by an enclosed stone aqueduct, and es- timated the length of the same from the confluence to the receiving reservoir at Manhattanville at 37 miles, and from the latter to the distributing reservoir, 5| miles. The report states that " the struc- ture of masonry has been adopted instead of iron pipes on the ground of its supe- riority in point of economy, durability, and efficiency."

Also, " the crossing of the Harlem river is proposed to be effected by means of an aqueduct bridge, 1,180 ft. long from abut- ment to abutment, consisting of 9 semi- circular arches. The height of the struc- ture, from the water-line of the river to the water-line of the aqueduct, would be 126 ft., exclusive of the hydraulic founda- tions, which would be from 10 ft. to 20 ft. more. A structure adapted to these di- mensions would be, of course, a work of considerable labor and expense, but by no means of paramount difficulty in either respect."

A feasible and durable plan for supply- ing the city of New York with water in abundance for not only its population at the time, but for the anticipated rapid in- crease in the future, had, since the year 1820, agitated the public mind, and vari- ous methods had been devised, and plans reported upon, none of which, at this pe- riod, proved acceptable to the citizens.

Major Douglass at once comprehended the importance of the undertaking, both as to the health and its bearing upon the

future growth of the city, and earnestly devoted himself to the successful accom- plishment of the work.

The first investigations were directed to finding an abundant and unfailing supply of pure, wholesome water, and at an eleva- tion that would allow of its flow into the city by its own gravitation, and with a head that would supply the upper stories of the buildings; and that could be used from the hydrants for the extinguishment of fires.

With these purposes in view, Major Douglass commenced his explorations and surveys in May, 1833, and in the following month he reported examinations of " all the chief tributaries of the Croton river and several of the remarkable reservoirs from which they derive their supply ; generalizing, meanwhile, the slope of the left bank with reference to the various routes of exit in the direction of the city. This is indeed a wonderful country for water, whether we regard the abundance or the purity of its fountains; and the in- tervening obstacles appear less formidable than I had supposed them to be."

On the completion of the preliminary surveys, and an estimate of cost, Major Douglass submitted a report to the Board of Commissioners, and the feasibility of the plan was so clearly shown, that the sanction of the Legislature was readily obtained in an Act of May, 1834, for pro- ceeding with the construction of the work. Douglass was appointed Chief Engineer.

As early as October, 1835, the surveys necessary for the location of the Croton dam were completed, but in opposition to the judgment of the chief engineer, the Commissioners changed the location to G-arretson's Mill, with a graduation of 40 ft. as its height.

Throughout his term of service Major Douglass found great difficulty in main- taining proper discipline in his corps of engineers, from the limited power with which the Commissioners invested him. They were unwilling to admit the neces- sity of an engineering department, and while Major Douglass fully realized the magnitude of the undertaking, the Board regarded it as little more than an extend- ed job of plain masonry, that might easily be constructed upon very economical principles.

There existed widely different views of economy and discipline between the first Board of Commissioners and the chief

MAJOR DAVID BATES DOUGLASS.

engineer, which finally led to a change that was universally regretted by the numerous friends of Major Douglass.

In October, 1836, he was removed from the charge which his experience and high scientific attainments so ably qualified him to prosecute to completion. His surveys, plans, drawings, and reports were sub- mitted to the Board, and by them adopted, and the construction of the work passed into other hands.

The various surmises and rumors upon the abrupt and unexpected discharge of Major Douglass by the Board of Com- missioners, in many instances prejudicial to his reputation, and from which he would not undertake to exonerate him- self, and although urged by several mem- bers of the Board to do so, is fully ex- | plained in the following letter to one of j the Commissioners, in 1840:

"In addressing a few lines to you on the subject of the unpleasant controversy which occurred in 1835-6, I cannot think it will be necessary to say much in the way of vindicating myself.

" You did not indeed witness but a very small portion of the violence and over- bearing of Mr. Allen's conduct to me, but enough must have been seen to assure you that it was wholly as involuntary as it certainly was free from personality on my part.

" Should you have any doubts on this point, they cannot but be removed when I ass are you that, painful as the contro- versy was in itself, and disastrous as the consequences have been to me to be thus thrown out of employment suddenly and unexpectedly, at a time when all other re- sources were unavailable ; to have a great work, the only one I had thought worthy of my ambition, taken out of my hands after being matured in all its most diffi- cult features; my professional character — the capital on which I and many others depended for our daily bread — assailed, — to have experienced all this at the hands of Mr. Allen, while my friends were im- portuning me to write, and members of the Common Council urging me to fur- nish statements,yet I resisted all influences and published not a line.

" It would have been veiy easy to show the unsoundness of every allegation brought against me, either in the Com- missioners' report or in the papers, from 1835 to the present time. I pledge my-

self to do this for you, or for the new Board, whenever you or they may desire it ; but I abstain from doing it before the public, simply because I resolved that no consideration of a personal kind should induce me to do any thing to disturb or interrupt the progress of the great work. Let me beg you to consider the exceeding injustice of the assertion often made by Mr. Alleys and Mr. Allen, that I had been a partisan in opposition to the Water Commissioners. Had I been such a parti- san these gentlemen would have heard from me in different style, but I have not been."

In 1837 and 1838, Major Douglass made an examination and report on the hydraulic power of the Monmouth Pur- chase ; also a reconnoissance of the coal region of the Upper Potomac ; and from 1837 to 1810, he was occupied in laying out the grounds of Greenwood Cemetery.

This beautiful locality was observed by him as highly appropriate to such a pur- pose, while engaged in the construction of the Brooklyn and Jamaica Railroad. These surveys, though they had no refer- ence originally to this object, were inci- dentally applied to it in the public lec- tures which he was called upon to deliver in Brooklyn, about the period of 1835. The original cemetery comprised only 178 acres, the ground declining in some places to valleys of less than 20 ft. above tide water, and in others rising to hills of more than 200 ft. Mount Washington is 216 ft., being the most elevated grouud in Kings County, and one of the highest points on Long Island. A heavy native growth of fine old forest trees suggested the name of " Greenwood " as appropri- ate for this cemetery. The artistic skill and classic taste of Major Douglass is beautifully illustrated in the laying out of this quiet and romantic home for the dead.

It contains 413 acres of hill and dale. Mount Auburn is beautiful, Laurel Hill has its charms, but none of the cemeteries of the country can compare with Green- wood in the wonderful grandeur of its views, its variety of landscape, and its ex- tent.

The avenues extend for nearly 25 miles, and it has several hundred miles of walks and paths within its enclosure.

From 1839 about $5,000,000 had been received, and nearly all of it expended on

VAN NOSTRANDS ENGINEERING MAGAZINE.

improvements. To grade the grounds, and lay out the avenues and walks was an immense work, and it has been continued through many years, not being entirely completed even now.

The principal entrance to Greenwood is on Fifth avenue, South Brooklyn ; the gateway is a magnificent and costly struc- ture ot Gothic form, and constructed of the finest brown sandstone.

It is very large, and presents an im- posing and massive appearance.

This gateway is probably the finest piece of architecture of its kind in this country.

In his letter of resignation to the Board of Trustees of Greenwood Ceme- tery, of which he was President, tendered in January, 1841, Major Douglass re- marked : " The local organization and the laying out of the grounds is now essentially completed. To have left this in an imperfect and unfin- ished state would have incurred the loss of much previous labor. I have felt it imperative, therefore, to remain in office at all hazards until it was finished. It has been a work of much greater labor than I supposed when I commenced it. The extent as well as the varied features of the ground have called for long-con- tinued, oft-repeated, and very careful study ; and this I have given it, but with what effect cannot be seen until the design shall have been in some degree carried out by the opening of the ave- nue."

The immediate cause of Major Doug- lass's resignation was his acceptance of a call to the Presidency of Kenyon Col- lege, in Ohio.

Before leaving for his new charge he submitted the plans and drawings for the improvement of the cemetery grounds to the Board. Mr. J. A. Perry, of Brook- lyn, writing upon the subject a year sub- sequently, observed :

" Anything about Greenwood, and es- pecially its long-desired success, would not be an uninteresting theme to its old and faithful friend. "We are now opening our avenues through the forests, and they open most beautifully. Having, providentially it would seem, nothing to occupy my time since Max*ch last, I have devoted it all to Greenwood ; delightful work, now that it is crowned with suc- cess, has it been. In June we propose to

consecrate our grounds. It is bat meet that one who has contributed so greatly to the establishment, and developed so admirably the beauties of Greenwood, as we delight in thinking you have done, should participate in the ceremonies of that occasion. Can you not be with us '? "

Major Douglass replied as follows :

" Believe me, you could not have done me a greater favor than in thus commu- nicating the future brightness of Green- wood. My own associations with it are as fondly cherished, and all my recollec- tions of it as fresh as ever. How delighted would I be could I promise myself, with any degree of assurance, the pleasure you hold up to my view so temptingly, of joining you in the approaching consecra- tion ; but I fear it is impossible.

"lean realize how delightful a relief the Greenwood improvements must be to your mind. Pressed and borne down as I frequently was while there engaged, its associations were always vivifying and gladdening to me. Its deep shades and quiet retreats, its old oaks and green cedars, the umber foliage during its In- dian summer, the setting sun from Mount Washington, its breezes and its flocks of birds — everything about it was unlike anything else in this world. I yeaim to see them again. Indeed, everything about Brooklyn continues to interest me as much as ever. No lapse of time can efface the smallest of the recollections by which it is endeared to me."

The following letter from Professor Olmstead, of Yale College, to Rev. Malcolm Douglass, indicates the feelings of those with whom Major Douglass was early as- sociated, and the deep interest his class- mates manifested in his subsequent varied and brilliant career :

" I send herewith the interesting letter addressed by your honored father to his classmates at their thirty years' meeting, in 1S43. It was read in the meeting, and listened to with lively interest, but with deep regret that the writer could not make one of our most delightful party. Profes- sor Douglass was justly regarded as a member who had done great honor to his class, by his gallantry in the service of his country during the war of 1812, and by his eminence as a man of science, partic- ularly by the great public works which he projected, several of which remain as

MAJOR DAVID BATES DOUGLASS.

durable monuments of his genius and skill."

Major Douglass continued his associa- tion with Kenyon College until 1844, when he returned to the East, and occupied his time until 1848 in the active discharge of various duties, among which were the planning and laying out of the Albany Rural and of the Quebec Cemeteries ; the survey of the Albany Water Works ; the drainage and graduation of South Brook- lyn ; the planning a supporting wall for a portion of Brooklyn Heights ; in exami- nations and reports upon the best method for supplying that city with water, and the laying out of the grounds of the New Brighton Association, of Staten Island. In 1848 he was called to the chair of mathematics at Geneva (now Hobart) College, which he accepted, although other propositions were laid before him with offers of greater compensation.

Major Douglass died at his residence in Geneva, New York, October 21st, 1849, from the effects of a paralytic stroke, at the age of 59 years. His remains were deposited at Geneva. After the lapse of little more than 12 months they were re- moved to the Greenwood Cemetery, in answer to a request based upon the fol- lowing resolution by the Cemetery Board, December 2d, 1850, as follows: " Resolved, That two lots for the use of the family of the late Major Douglass be designated by the Standing Committee, and when the remains of Major Douglass are deposited therein, the said committee shall cause the lots to be suitably enclosed, and an appropriate monument to the memory of Major Douglass erected thereon." His remains now repose in that beautiful Necropolis, to the creation of which his admirable genius so largely contributed.

No monument to his memory has yet been erected there. At this period the only public memorial of his life and death is to be found in the large and richly stained monumental windows of the south aisle of Trinity Church, Geneva, upon which is traced the following in- scription: "To the glory and praise of God. The children of the late David Bates Douglass, filled with affection for his memory, and with devout gratitude for his paternal precepts and Christian ex- ample, erect this memorial window."

Major Douglass in stature was several inches above the medium height, slender,

but finely proportioned, with an energetic, earnest movement, and distinguished military presence.

His features, without being regular or handsome, were strongly marked and striking ; his hair was dark, and his eyes black, large, and restless; his voice deep- toned and firm. With brilliant conversa- tional powers he combined a manner of address, polished, quiet, and unostenta- tious. He was a favorite of the drawing- room and of the family circle.

Religious in his proclivities, he super- intended with pious vigilance the educa- tion of his family. His two eldest sons were graduates of Kenyon College.

The eldest, Charles Edwards, was des- tined for the church. After graduating, he passed regularly through the Univers- ity course at Trinity College, Hartford, Connecticut, and is now the Rector of St. Paul's Church, Windsor, Vermont.

From him many valuable papers were obtained and used in the preparation of this imperfect sketch of his distinguished and venerated father. The fourth son, Henry, after going partly through a col- lege course, entered the U. S. Military Academy at W'est Point, and graduated in 1851. Major Douglass also left four daughters.

One might deem the years of Major Douglass comparatively few in number, and his death premature, but in glancing at the leading events of his life from his early graduation at Yale College to the period of his death, with the reflection that within the narrow limits of a biogra- phy of this nature, only the professional incidents could be recorded, he had lived long in useful mental exertion.

Every hour had been occupied in earn- est labor for the cultivation of others, or in plans for the military defence or public improvements of his country. While Pro- fessor of Architecture of the University of the City of New York, the university buildings were constructed from his de- sign, being the first introduction into this country of the Elizabethan style.

The following tribute to the peculiar qualities of Major Douglass as a teacher, and his character as a Christian, is from the sermon of the Rev. Dr. Hale, Pres- ident of Hobart College, upon the death of Major Douglass, and coming from one who was so well qualified to judge, and who had b<.en associated with him as a

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TAN NOSTRAND'S ENGINEERING MAGAZINE.

teacher and a neighbor, gives it greater value and force :

" By the caste of his mind and the qual- ities of his heart, no less than by the ex- tent of his attainments, he was fitted to be a teacher. He had a rare facility in acquiring knowledge and making himself master of it, in all its broadest principles and minutest details; but it seemed to be his great pleasure and the peculiar ten- dency of his mind to impart it.

" He loved books, but if I may judge from my acquaintance with him, which was in- timate, he was less a reader than a thinker. He looked reverently upon books — books which he desired and sought — and read them, not for amusement, but a serious occupation of the mind and heart. He

read, therefore, not superficially, but in- tently, as he would have listened to the voice of a teacher in answer to earnest and importand inquiries. He possessed great powers of analysis, which he exercised not in a captious or doubting spirit, but that he might better know and form the material whereon to exercise that faculty of his intellect which was more pecu- liarly his characteristic, the constructive talent.

" Hence, his views, his opinions, his aims, were all definite. Hence, the depth and clearness of his instruction. Hence, in conversation he was still the teacher, and without any of the forms of argument, his discourse, clear in its own light, was full of information."

NOTES ON FIEE-BEICKS.

By Lject. G. E. GROVER.*

Fire-bricks are so named from their property of comparative infusibility when exposed to very high temperatures. I say comparative, because no known mate- rial seems to enjoy absolute immunity from decomposition under the attacks of unlimitedly intense heat. Even the nomi- nally infusible substances (pure silica, alumina, lime, and magnesia ; the natural varieties of rotton-stone — a very alumin- ous silicate of alumina, decomposed from rock ; and the silicates of magnesia, talc, asbestos, steatite or soap-stone), have been known to succumb in the flame of an oxyhydrogen blowpipe, or between the poles of a galvanic battery.

It is, however, clearly unnecessary to discuss in this paper any materials but those practically obtainable in large quan- tities ; and of these the chief components in Great Britain are the so-called fire- clay, with the exception of the silicious Dinas rock in the Vale of Neath, Glamor- ganshire, to which fuller reference will be made hereafter. Clays proper are chemi- cal compounds, occurring under different phases in numerous geological formations, and consisting of hydrated silicates of alumina, either alone or in combination with silicates of potash, soda, lime, mag- nesia, iron, manganese, etc. Though a

* Ext-act from a paper presented to the Corps of Royal Engineers.

sediment from water (being, in fact, de- composed rock, characterized by a very minute division of constituent particles), they are tough and plastic, differing from mud in these respects, as well as in the absence of vegetable and animal matters. The plasticity and tenacity of argillaceous earths are due to the prominence of the ingredient alumina (which has a strong affinity for water), and are diminished by the presence of iron, lime, and magnesia. Clays appear to be the result of the slow decomposition by water of felspar, or some, similar material, containing either potassa or soda.

The so-called fire-clays owe their re- fractory properties to a variable absence — differing, that is to say, in different clays — of lime, oxide of iron, and the alkalies of magnesia, potassa and soda. In refractory bricks, formed of baked fire- clay, the silica may be considered as a passive ingredient, acting mechanically to prevent excessive contraction, whilst the alumina forms the cement which binds the particles together.

The following is a list of the usual con- stituents of fire-clay, with their respective chemical symbols :

Silica (or silicic acid) Si 02

Alumina (or sesquioxide of alum- inum) Al 03

Peroxide (sesquioxide or red ox- ide) of iron Fe2 03

NOTES ON FIRE-BRICKS.

Lime (oxide of calcium) Ca O

Magnesia (oxide of magnesium).. . MgO

Potassa (oxide of potassium) K2 0

Soda (oxide of sodium) Na2 O

and the following table details, for the sake of example, their proportions found in chance samples of several well-known classes of English fire-brick.

	Silica.	Alumina	Peroxide of iron.	Lime.	Magne- sia.	Potassa.	Soda.	Titanic acid.	Total.
Stourbridge Ptympfon, Devonshire Newcastle-on-Ty ne	65.37 74.02 64.63 58 08 65.25 59.35 84.65 58.92 97.62	26 48 21 37 29.78 36.89 29.71 34.32 8.85 35 65 1.40	5 68 1.94 3.23 2.26 3.07 2.35 4.25 2.49 .49	.28 .40 .42 .55 .40 .43 1.90 .39 .29	.33 .36 .41 .14 .61 .22 .35 .35	1.26 .82 1.09 .20 .43 3.33 i'.u .10	.30 .09 .24 1.88 .12 i.06 .10	.30 '.20 '.41	100.00 J 00.00 100.00
Burton-on-Trent	100.00
Wort lev, near Leeds	100.00
Poole, Dorsetshire Hedgerley, Buckinghamshire. Kilmarnock, Ayrshire Dinas, Glamorganshire	loo.oo 100.00 100.00 100 00

It should be observed, however, that the inftisibility of any substance depends, not merely upon the chemical natures of its constituents, but also upon the manner in which those constituents are combined with one another. For example, granite, per se, is infusible at ordinary high tem- peratures, whilst pounded granite (or, in other words, a fine powder of quartz, felspar,, and mica, mixed in the same pro- portions) can be readily melted in the same degree of heat. The porosity in structure brought about by a coarseness of elementary particles would seem to add to the chemical infusibility of a ma- terial.

A most important physical peculiarity of clay — second only in importance to the property of plasticity— is its behavior on exposure to high temperatures.

It is well known that, as a general rule, all bodies are expanded by heat. Clay, however, appears to be an exception to this rule, being a mechanical mixture and not a homogeneous body; and it was ob- served by Mr. Wedgwood, that alumina, or clay in which alumina predominates, on being exposed to a red heat, begins to contract, and, as the heat increases, con- tinues to contract regularly until it finally vitrifies, and so (by its permanent dimi- nution in bulk) furnishes an approximate indication of the temperature to which it has been subjected.

Hence the "Wedgwood pyrometer, which, by a comparison of the diminution . in diameter of small cylinders of alumi- nous porcelain clay, placed between cylin- drical brass rods forming a graduated gauge, supplies an empirical text of the degree of heat which those cylinders have

sustained. It is proper, however, to re- mark that, as clay is a heterogeneous sub- stance, and its contractions are not of ne- cessity regular at different temperatures, this pyrometer — though useful for most practical purposes — fails to record the degrees of heat with precise accuracy; and there has yet to be devised a ther- mometer which will indicate with absolute exactness the very high degrees of furnace temperature.

Again the moulds of bricks are usually made larger than the intended products by abont ^ or ^ of each dimension, that being the ordinary proportion in which the dimensions of the brick shrink in burning. The cause of this str uge prop- erty of clay is, I believe, still a matter of question.

By some it is supposed to result from an expulsion of the water of combination, and a consequent contraction of the primary pores, which produces an increased den- sity of the mass. By others it is ascribed to an actual rearrangement of the con- stituent atoms by the influence of heat, which brings them into more intimate union. But, whatever be the cause, the property is important, and noteworthy in its bearing upon the present subject of investigation.

Fire-clays able to resist exposure to a high temperature without melting or be- coming, in a sensible degree, soft and pasty, occur in various geological forma- tions, and they abound in the coal meas- ures in the carboniferous system. The following are a few of the best known localities in this country whence fire-clay is extracted : the valley in Derbyshire, between Burton-on-Trent and Ashbv-de-

VAN NOSTRAND'S ENGINEERING MAGAZINE.

la-Zouch ; .the Southbridge district, in Worcester and Staffordshire (including Dudley, Tipton, Gornal, etc.); Newcastle- on-Tyne, in Northumberland ; Wortley, near Leeds, in Yorkshire (including Elland, Storr's Bridge, Stannington, etc.; Wolverhampton, in Staffordshire ; Poole, in Dorsetshire ; Newport, in Monmouth- shire ; Kilmarnock, in Ayrshire ; and Glenboig, at Coatbridge, near Glasgow, i in Lanarkshire. To these should be I added, as sources of our most celebrated | fire-bricks, the aforesaid Din as rocks, in j the Vale of Neath, Glamorganshire ; the kaolinitic refuse from porcelain clay at St. Anstell's, Cornwall, and Plympton, Devon- shire ; and a peculiar stratum of sandy

loam, known as "Windsor loam," over- lying the chalk at Hedgerley, a Tillage about five miles north of Slough, Buck- inghamshire, whose " red rubbers," were, iu the times of our grandfathers, thought to possess surprisingly refractory powers. In the following table is shown the per- centage of the three most important con- stituents of these different kinds of fire- bricks, which have been practically tested in the Royal Arsenal furnaces, and ana- lyzed by Mr. Abel, F. R. S., Chemist to the War Department. The maker's names are, for obvious reasons, omitted ; but samples of most of these fire-bricks are to be seen in the School of Military Engin- eering at Chatham :

	Maker.	Silica.	Alumina.	Peroxide of Iron.	Alkalies , Waste, etc.
	A A A B G F G L N P Q Q R S T V X	65.65 67.00 66 47 58.48 63 40 59.80 63 50 56.65 65 20 68 60 75.89 76 70 84 65 59.48 96.20 59 10 62.50	26.59 25.80 26 26 35.78 31.70 27 30 27.60 35.81 29.69 23 60 2161 2010 8.85 31.45 2.00 35.76 3400	5.71 4.90 6.63 3.02 3.00 6.90 6.40 2.99 3.07 4.70 1.96 1.70 4.25 6.90 .28 2.*0 2.70	2.05
Ditto	2.30
Ditto	.64-
Ditto	2.72
Ditto	1.90
	6.00
Ditto	2.50
	5.17
	2 04
	310
	.54
] )itto	1.50
Hpdsierley	2 25
	2.17
	1.70 2.64
	.80

Experience with these samples justifies the general assertion that the refractory values of fire-bricks vary inversely with the amount of iron contained in them ; and, as a general rule, the presence of 6 per cent, of peroxide of iron warrants the absolute rejection of a fire-brick. This component usually takes the form of little black specks or mottled particles which are embedded in the material, and can be plainly detected upon breaking the brick.

The essential qualities of a good fire- brick may, I think, be classified as fol- lows : Infusibility, regularity of shape, uniformity of composition, facility for cut- ting, strength and cheapness.

The property of infusibility has already been touched upon in this paper ; and it seems to forbid in the brick's composi- tion so much as even 5 per cent, of per-

oxide of iron, or 3 per cent, of combined lime, soda, potassa, and magnesia. Gen- erally speaking, a fire-brick should con- tain either silica or alumina in excess, according as it is intended for exposure to extreme heat, or for a possible contact with metallic oxides, which would exert a chemical reaction, decomposing it and acting as a flux. Thus, in theory, the arches of a furnace should be built of silicious bricks ; its sides, bridge, and neck of aluminous bricks. Dr. Percy considers ( " Metallurgy," p. 235) that, to boast properly of the quality of infusibil- ity, a fire brick must well resist sudden and great extremes of heat ; it must sup- port considerable pressure at a high temperature without crumbling ; it should not melt or soften in a sensible degree by exposure to intense heat long and uninterruptedly continued •, and it

NOTES ON FIRE-BRICKS.

should withstand, as far as practicable, the corrosive action of slags rich in pro- toxide of iron. He recommends as a test, that the fire-clay should be formed into small sharp-edged prisms, which, on being enclosed in a covered crucible and subjected to an extreme temperature in an air or blast furnace, would denote a very high degree of refractoriness if the edges remained sharp, an incipient fusion of the material if the edges are rounded, and a thoroughly inferior quality of the fire-clay if the prisms were melted down.

M. Brongniart recommends the follow- ing process of test ("Traite des Arts Ceramiques," tom.l, p. 342 : "Sionveut jnger la qualite refractaire d'une brique, e'est de faire itn petit massif de six ou huit de ces briques sur deux rangs, et de l'exposer, un rang en evant dans un four a porcelaine a Ten tree du feu clans le four. Le poids affaisera les inferieures si elles sout seulement ramollissables. Le rang anterieur ne doit pas entrer dans le judge- ment ; il est toujours attaque, quelque refractaire qu'il soit ; maisil sert a garan- tir le rang posterieur de Taction de la potasse des cendres a laquelle la terre la plus refractaire ne peut resister. C'est done sur les alterations de ramollissement, de fusion, ou de boursouflement du rang posterieur qu'on peut juger la qualite re- fractaire d'une brique. Aucun moyen d'analyse ou d'essai en petit ne peut sup- plier a ces veritables essais techniques." It may be remarked, however, that in this investigation, analysis, theory, and practice nearly always agree pretty closely.

In many works there is adopted the rough and ready, but very efficient mode of comparing the relative qualities of fire- bricks by placing them side by side upon the biidge of a reverberatory furnace, where they are subjected to the same heat and the same corrosive action of the fuel ; and show very clearly, after a few days or weeks firing, which brick can best with- stand these destructive influences under precisely similar conditions. I think this test is even superior to those suggested above. The corrosive action of suspended coal-dust in fluxing and gradually cutting away the exposed surfaces of brickwork, is extraordinarily great, even superior to the disintegrating influence of extreme heat.

Hence a great claim to economy of the

Siemens Eegenerative Gas Furnace ; and Mr. Siemens affirms that the heat at which a tuitably designed furnace can be worked is limited in practice only by tbe difficulty of finding a material sufficiently refrac- tory of which it can be built.

Regularity of Shape requires that the brick's opposite sides should be truly par- allel planes (excepting, of course, the special case where key hollows are left;, and then arises sharp right-angled edges. The necessity for this requirement is obvious. In all forms of brickwork regu- larly moulded bricks produce even joints, prevent settlements, and effect economy as well as stability in the w7ork. But in fire-brickwork, especially, an uniform shape of each individual component of the furnace permits, under extreme changes of temperature, an uniform ex- pansion or contraction in all directions ; it tends to preserve the relative propor- tions, and thus to insure the general sta- bility of the entire mass of the brickwork.

Uniformity of Composition. The brick on fracture, should present a compact uniform structure — not necessarily close, for indeed some maintain that a coarse grit of texture is the chief requisite, and that a coarse uniform structure, though pleasing to the eye, is not favorable to the refractory powers of a fire-brick, since the particles should have a facility for contraction or expansion under heat, and the air cavities act as valuable non- conductors of heat. But the brick should be free from stones, cracks, and irregular air-hollows ; and, on being struck, it should emit a clear ringing sound. The existence of this property usually involves that of the next.

Facility for cutting, i. e., a capability for being easily dressed with perfect accu- racy, so that the brick shall not require a very violent blow, or split in a direction other than intended, or fall to pieces under a trowel. This property is an ad- vantage in both building and repairs ; but that it is not of paramount impor- tance may be inferred from the fact that the best firebricks ever used in the Manufacturing District least fulfil this condition ; yet no one, not even the bricklayers, whose tools suffer from the bricks' excessive hardness, would discon- tinue their use on this account. A fire- brick should never have its dressed sur- face, but only its " fire-skin " exposed to

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VAN NOSTRAND'S ENGINEERING MAGAZINE.

the furnace flame, for reasons similar to those against the exposure of the rubbed surface of an ordinary building brick to the weather. Hence it is to employ as many forms of differently moulded brick as possible, and the accompanying dia- grams show the dimensions of the spe- cial shapes found most convenient in actual practice.

Though it is impossible to propound an exact rule as to the percentage of the cost of labor and materials in furnace-work, their relative proportions may be roughly said to average 33 to 67 in new work, and 60 to 40 in repairs, such as cutting out bridges, clearing the necks, slag-holes, etc.

Strength is obviously necessary to enable the bricks to avoid breakage in transport, and to withstand the pressure and cross strains to which it will be subjected when built into the work. It is stated by Ean- kine ("Manual of Civil Engineering," p. 367), that the resistance to crushing by a direct thrust — the bricks being set on edge in a hydraulic press — is per sq. in., in weak red bricks, from 550 lbs. to 800 lbs. ; in strong red bricks, 1,100 lbs.; in fire- bricks, 1,700 lbs. But experiments re- cently made in the Royal Arsenal upon isolated cubes of 1| in. side, cut from fire- brick "soaps" and placed between small squares of sheet lead, gave the following results:

Cracking Crushing

weight, -weight,

lbs. per lbs. per

sq. in. sq. in.

1,478 2,400

1,156 2,245

889 1,512

1,689 2,666

1,123 1,288

2,134 3,378

1,067 1,556

Stourbridge A

Ditto D

Newcastle C

PIvmpton Q

Binas U

Kilmarnock W

Glenboig X

and the average crushing weight of or- dinary stock bricks was found to be from 666 lbs. to 866 lbs. per sq. in. Hence, all fire-bricks known may be said to have a strength far in excess of that which would be ever required of them in actual work.

Cheapness may appear an impolitic, and, therefore, unworthy consideration, but it practically determines the selection of 9-10ths of the fire-bricks used in this country.

For example, the freightage to Loudon per ton (from 320 to 370 9-inch bricks) costs, on an average, 5s. 6d. from New- castle, and 13s. from Stourbridge. Hence

the great advantage possessed, cceteris paribus, by the manufacturers of the former place over those of the latter. And supposing the cost in London of one class of fire-bricks to be one-half that of an- other, and the above statement to be true, viz., that in the cost of new work, labor: materials, ::33:67 it will readily be understood that, from a momentary point of view, it might be perfectly imma- terial to the furnace owner whether he used the cheap or the dear fire-bricks — always supposing that the former be not so bad as to disintegrate and drop into the metal, and that a comparatively fre- quent " standing" of some furnaces in his establishment were of no great conse- quence to his pocket.

But, in point of fact, the pros and cons of this question are seldom so nicely bal- anced as in the hypothetical case I have assumed, and the invariable experience of the manufacturing district is that the best fire-bricks prove always to be ultimately the cheapest.

I now propose to attempt some general descriptions of the usual processes in vogue for making certain of the best known classes of English fire-bricks. In this manufacture more than ordinary care is found requisite to insure an uniformly regular success from its processes, and it should be observed that there is almost as slight a similarity between the modes of manufacturing fire and building bricks as there is analogy between their uses. With the former,- use involves incessant repair, and after a few months' wear in a busy furnace, entire renewal; with the latter, even if of worthless quality, a builder, careless of reputation and indif- ferent to the possible discredit of distant failures, can often construct without fear of immediate detection.

Yet, even with this practical check upon quality, all experience in fire-bricks in- duces a certain wise toleration, so that isolated or exceptional cases of failure should not be allowed to justify the sweeping condemnation of an entire class.

In the following remarks care will be taken, for obvious reasons, to avoid iden- tifying those makers who have courteously allowed the writer to inspect their works.

Yet the official recommendations of a certain agent's fire-lumps taken in com- pany with the experience of some of the most eminent iron and steel firms in

NOTES ON FIRE-BRICKS.

11

Sheffield, may be allowed to sanction the opinion that a very high degree of excel- lence should be attached to the fire-clay manufactories of the Burton-on-Trent district. With these manufactories, there- fore it is proposed to begin.

Bubton-on-Trent.

The clay is dug at a depth below the surface of about 20 ft. from open pits whose sides display the following strata :

Thickness, ft. in.

1. A common earthy or brick clay (burns

white) 6 0

2. A land of coal, locally termed " smut "10

3. A kind of marl, locally termed

« ' clunch ' 6 0

4. A kind of coal, locally termed "smut" 0 6 5 Marl 6 (i

6. Eire-clay:- a bluish-black or slate-

colored clay, of which the upper stra- tum 10 in. or 12 in. thick (locally termed " top black") is best . 6 0

7. A kind of coal, locally termed "smut" 1 0

8. Bottle-clay, for sewage and drain pipes 9 0

9. Iron-stone and " smut " 2 0

10. Pot clay, for yellow ware succeeds.

The fire-clay is worked up into bricks as fast as it is obtained from the pits. It is not here customary, as in many dis- tricts, to " weather " the clay by long ex- posure before use, but it is sometimes moistened with water in order to lay the dust.

It is usually transported from the pits, and through the works, in trucks upon a tramway of 1 in. rails and 18 in. gauge; but the wire-rope overhead transport system is being generally substituted, and this will permit the easy transport of about a 4 cwt. load in each of the " trunks " or boxes upon an endless steel wire rope suspended from poles, passing over Fowler's clip drum pulleys, and worked by small portable steam engines.

The clay is pulverized in Carr's Disin- tegrator, composed of four cylindrical cages, 6 ft. 3 in., 5 ft. 7 in., 4 ft. 9 in., and 4 ft. 7 in. in diameter, arranged concen- trically on wrought iron disc plates, so that the steel bars or beaters are about 4 in. apart, and 1 ft. 4 in. wide.

These sets of beaters revolve in oppo- site directions, by means of an open and crossing driving band wor-king their disc axles, so that the first and third cases rotate in a direction contrary to that of the second and fourth ; and they make

about 200 revolutions a minute. The clay is lifted and delivered throxigh a hopper into the interior of the machine (whose capacity is about 31 cubic ft.), by means of buckets upon a " Jacob's ladder" end- less band, 10 in. wide. It is then driven through the mill, and ejected from it in a finely granulated state, by centrifugal force, at the rate of from 20 to 30 tons an hour. The clay is in this manner suffi- ciently pulverized to render a riddle un- necessary, if meant for fire-bricks ; but if for mortar or cement clay, it is passed through a wire mesh of 5 or 6 to the inch. The chief advantages of this machine over the ordinary " edge runner and pan " system of a mortar mill, consists in its ability to pulverize a moist, plastic clay as well as a dry clay, and in its power to disintegrate about 200 tons of clay per diem ; in which time the roller and edge runner process can, with the same steam power, grind only about 50 tons.

The bricks are fired in Hoffman and Licht's annular kilns, where, in successive chambers (each 15 ft. wide, 8 ft. 6 in. high, and holding about 20,000 bricks), different sets of bricks are dried, heated, burned, and cooled, by the currents of air feeding and escaping with the products of combustion from the same one fire. This form of kiln is found most economi- cal in consequence of, firstly, the fuel being burnt with air already at an incandescent temperature ; and, secondly, the waste heat from both cooling and burning goods being entirely utilized in drying the new, fresh bricks about to be burnt, and raising them to a high temperature. The con- sumption of fuel in this form of kiln is, therefore, very small, in comparison with that in one of the ordinary form of con- struction ; and it is found that the burn- ing of 1,000 bricks in the annular kiln requires only 2| cwt. of Stavely dust coal, at 5s 6d. a ton, instead of 20 or 25 cwt. of large " Grosby slack" coal at 7s. a ton.

The difference of cost for coal alone, therefore, amounts to about 8s. per 1,000 bricks, and the saving of labor is also very considerable. The bricks so fired are peculiarly well formed, and well burnt ; the former, because they escape the addi- tional handling and transport required by the dry-shed process ; the latter, because they are practically annealed by the gradual heating and gradual cooling in the successive processes of drying, heat-

12

VAX NOSTRAND'S ENGINEERING MAGAZINE.

ing, firing, and cooling, which extend over a period of about three weeks.

The Stourbridge fire clay district, in- cluding Amblecote, Brierly Hall, and the Lye, covers an area of from 8 to 9 square miles, with 6 fire-brick manufactories in Worcestershire, and 7 in Staffordshire.

From the pits on these works about 100,000 tons of fire-clay are annually raised, and the supply of fire-bricks has annually increased within the last 15 years from 14,000,000 to 30,000,000 per annum. In the neighborhood, the Quarry Bank Church is built entirely of Stourbridge fire-bricks; the Brockmoor Church is built partly of fire-bricks and partly of blue- bricks; and fire-bricks have been extens- ively used in the construction of the rail- way stations between Stourbridge and Birmingham.

The processes through which the clay passes during its manufacture into fire- bricks are 9 in number, viz. : digging, weathering, grinding, sifting, tempering, moulding, drying, and burning.

The Stourbridge fire-clay, or coal meas- ure marl — a species of shale or slate-clay — is dug from pits (whose shafts are 6 ft. or 8 ft. in diameter, and steined) varying in depth from 120 ft. to 570 ft. It is gen- erally found below 3 workable coal meas- ures between marl or rock and an inferior clay. The former, overlying the fire-clay, is generally about 48 ft. thick. The fire- clay seam averages 3 ft. in thickness, never exceeding 5 ft., and thinning down to 5 or 6 in. when close to faults or small disturbances in the measures.

The middle stratum of the seam is al- ways selected for the fire-clay, the top and bottom being thought too " strong." After being raised from the pits the fire- clay is picked over by women, who select the best lumps or " kernels " for glass- house pots, and reject for stains and min- eral impurities. The pot clay is only found in small quantities — about sufficient for the glass manufactories — and costs on the spot 55s. per ton, whereas ordinary fire- clay costs on the spot only 10s. per ton ; and 4 tons of clay (about 3| cubic yards) are required to make 1,000 9-in. fire-bricks, whose local price is 50s.

Some of the glass-house pots recently made for one of the large plate-glass manu- facturers at Ravenhead, weighed as much as 30 cwt. each when dry, and stood 6 ft. high.

The clay is exposed in spoil heaps over as large an area as can be secured, for from 3 to 18 months, according to the state of the weather. The action of frost, as with ordinary brick earth, is of great service in disintegrating the compact tough lumps of clay, and in dry weather the clay is frequently watered. In very wet weather a three months exposure will suffice for its proper " mellowing" or "ripening;" it ultimately slacks or falls to pieces. When new it is termed in the local phraseology " short and rough ;"' after due exposure it becomes " mild and tough." On some of the works the spoil heaps of clay contain over 10,000 tons, and it is estimated that 7 tons measure about 6 cubic yards.

After sufficient weathering, the clay is ground in a circular pan by 2 rollers or cylindrical stones, shod with iron rims 2| in. thick, and weighing from 2| to 3 J tons a piece. They are driven by steam.

After being ground, the clay is carried on an endless band to a " riddle" of about 4 or 6 mesh to the inch for fire-bricks ; 6 or 10 mesh to the inch for fine cement clay ; 12 or 14 mesh to the inch for glass- house pot clay ; the large-sized mesh being used for the sifting of the clay in wet weather. The large particles which will not pass through the " riddle" are carried back on an endless band to the pan and then re-ground.

As a general rule it is only for very large fire-brick lumps (such as blast fur- nace "tyraps," 40 in. long, and 11 in. by 10 in.) that re-ground pots, crucibles, or bricks locally termed "grogg," are added to the clay before grinding ; and fire ce- ment clay is always ground pure.

After passing through the " riddle," the clay is tempered, or brought to a proper degree of plasticity by the addition of water.

It is then thoroughly stirred and knead- ed in a circular cast-iron pug-mill by re- volving knives projecting from a vertical shaft driven by steam power.

The clay is forced down by the obliquity of the rotating knives, and steams slowly from a hole near the bottom, whence, after being cut by wires into parallelopipe- dons, it travels on in an endless band to the moulding sheds.

The bricks are then moulded by hand in the usual manner, in moulds 10 in. by 5 in. by 3 in., or thereabouts, and dried

NOTES ON FIRE-BRICKS.

13

at a temperature of 60 or 70 deg. in sheds 120 ft. long and 30 ft. wide, beneath whose floors run longitudinally two flues, heated by small furnaces. In tine weather, however, the sun's heat is made to econo- mize fuel.

The bricks are burnt in circular-domed kilns, or cupolas, locally termed " ovens," where they remain from 8 to 14 days, being fired with the real intensity of flame, or white heat, for about 4 days and 3 nights ; they usually require 7 days to cool down. The tire is slowly increased, and gradually lowered ; the time of burn- ing is regulated by a kiln man in charge, who inspects the baking bricks from time to time through holes in the domed roof of the " oven." A chimney stack is on the outside of the kiln, and the flame burns with a down draught descending- through holes in the floor, the fire-holes being merely openings left in the thick- ness of the wall of the kiln, and protected from the wind by buttresses long enough to allow room for the firemen to attend the fires. The coal is, of course, obtained from the pits which provide the clay. Most of the kilns hold each 12,000 bricks, but some are made large enough to con- tain each 30,000 or 35,000 bricks, the ca- pacity of a kiln being roughly calculated upon the assumption that 10 bricks re- quire 1 cubic ft. of space in the kiln.

For conveyance of the clay and bricks about the Stourbridge works, little trucks called " skips" are employed in the pits, and throughout the brick-fields. Their platforms, standing 1 ft. high, are 4 ft. square, and consist of 1\ in. planks. Tlieir wheels, of cast iron, are 10 in. in diameter, with 2 in. axles. The rails, 2 ft. apart, consist of \ in. wrought-iron angle rails, 3 in. wide, and \\ in. high. . The mode of fire-brick manufacture in the Newcastle district differs from that of Stourbridge in a very few and unimpor- tant particulars.

The clay, in a spoil heap of 30,000 tons, is often exposed for 7 or 8 years, during which time it is picked over by boys, who remove pyritous fragments exposed on disintegration.

When required for fire-bricks, it is ground by cylindrical edge-stones, weigh- ing 3 tons each, in a revolving pan, or else upon the ground, and then passed through a wire " riddle " of 6 or 8 mesh to the inch.

Throughout the works are 18 in. tram- ways, and pony trucks convey the ma- terials from place to place. After temper- ing, moulding, pugging, and drying, the bricks are burnt in kilns about 15 ft. by 14 ft., by 10 ft. high, holding each 15,000 bricks.

They are fired for eight or nine days, during which time 5 tons of coals are consumed. The flame and hot air pass from a fire-box at one end of the kiln to outlet flues at the other end of it, and thence into an external chimney.

About 80,000,000 of fire-bricks are pro- duced annually from the Newcastle dis trict. i. e., nearly three times the annual supply of the Stourbridge works.

Very excellent fire-bricks are made from the refuse of Kaolin or china clay, found in Cornwall and Devonshire.

Kaolin is produced by the disintegra- tion of " pegmatite," or felspathic granite, under the action of the carbonic acid and moisture of the atmosphere; it then be- comes basic silicate . of alumina. The kaolinitic fire-bricks, containing very little iron or lime, possess extremely refrac- tory powers, and have, in fact, been found in the Royal Arsenal air furnaces to be equal or superior in this respect to any other known fire-bricks in the king- dom.

With their rivals they compare as fa- vorably for economy as for endurance; but the former is, of course, a specially local advantage, which might possibly disappear in another district.

Kaolinitic fire-bricks enjoy, however, a very high reputation in lead-smelting fur- naces, converting vessels of the Bessemer steel process, the retort furnaces of gas works, kilns for burning iron pyrites, etc., etc. For the moderate heat to be with- stood by ordinary boiler seatings, a burnt compound of kaolin, sand, and local clay, in equal parts, is found to be as good as the fire-lumps ordinarily employed.

The refractory powers of clay will, of course, by the addition of pure silicious sand, which can be produced by grinding sandstone if it is not obtainable in a state of nature.

The Dinas fire-brick is well worthy of attentive consideration, if, indeed, solely for the reason that it is, in the opinion of Mr. C. W. Siemens, F. R S., the " only material of those practically available on a large scale, that I have found to resist

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VAN NOSTRAND'S ENGINEERING MAGAZINE.

the intense heat at which steel-melting furnaces are worked." Now the average heat of a steel-melting furnace, measured by electrical resistance, may be accepted as 2,200 deg. Centigrade (= 3,992 Fah- renheit), and that of the ordinary air- furnace, at welding heat, as the former, the Dinas brick, will last, it is found, for four or five weeks, though their thick- ness will, in that time, have been reduced from 9 to 2 in. But these extraordinary results, it should be remembered, have been only obtained in the Siemens Regen- erative Gas Furnace, wherein, the flame being quite pure and free from the sus- pended dust which is usually borne from the fuel by the keen draught of air through an ordinary reverberatory fur- nace, the brickwork is not fluxed on its surface, and gradually cut away thereby, but it fails, if at all, from a general soft- ening and fusion throughout the entire mass. For the ordinary puddling mill or air furnaces, the Dinas bricks, not- withstanding their ability to resist very high temperatures, are somewhat trouble- some in actual practice. They are very friable, porous (and thus imbibe moisture freely), they swell extremely with heat,

and do not contract to their original di- mensions.

If allowed to cool down (and it is cus- tomary to let the furnaces " stand," in most works, from mid-day on Saturday till mid-day on Monday) they are apt to crack, flake in fragments, and then fly to pieces in consequence of the decrepitation of portions of the quartz composing them. From their extreme tenderness they are unlikely to prove durable if applied in portions of furnaces where they would be subjected to much mechanical wear.

Yet their refractory powers are remark- ably great, and they bear a very high repu- tation with many owners of copper-smelt- ing, iron, glass, gas-works, coke ovens, etc., and they seem to be highly esteemed for the arches of reverberatory furn aces in the copper works of Swansea, at Middles- borough, and at Ebbw Vale.

The tabulated analyses show the high percentage of silica which these bricks contain ; and from their silicious nature it is obvious that they should not be ex- posed to the action of slags rich in metal- lic oxides, or to the fumes from lead ores, or to proximity with alkaline sub- stances generally.

IRON ELECTROTYPE.

From "Engineering."

The art of electrotyping, which owes its discovery almost to accident in the year 1839, has since that time grown into a very extensive branch of manufacture. The discovery of this most useful art was made almost simultaneously in England and in Russia. In England Mr. Thomas Spencer and in Russia Professor Jacobi have to be individually credited with the invention, which has since been develop- ed and brought to the degree of perfection in which we now find it in daily practice. So far the reproduction of engraved plates, medallions, and objects of art has only been effected in the softer metals, such as gold, silver, and copper, although attempts were long since made to reproduce them in iron. Few persons probably were aware, however, that this important object had been accomplished, until, like our- selves, they saw a case containing some beautiful specimens of iron electrotype in one of the corridors of the late Interna-

tional Exhibition at South Kensington. The specimens were placed there about 3 months before the close of the Exhibition, and were exhibited by Messrs. Bryan, Donkin and Co., of Bermondsey, as agents for the inventor. These specimens con- sisted of bank-note and various other plates, medals, medallions, and a page of printing type electrotyped in iron. This new process has been perfected by M. Eugene Klein, who is at the head of the chemical department of the Imperial State paper manufactory in St. Petersburg. Many difficulties nave arisen and have been successfully surmounted in develop- ing this process to its practical issue. Attempts were made to effect the object so far back as the year 1816, but which were unsuccessful, and it was about 20 years before the problem was definitely solved. The importance and reality of the progress, however, are now unques- tionable, and an extended knowledge of

IRON ELECTROTYPE.

15

the process must inevitably lead to its general adoption. At the present time we believe its application is confined to the Russian Imperial State paper works, where it has been in active operation for the past three years, the iron plates replacing those of copper for bank-note printing and for other similar purposes. The ap- plication of the invention, however, ex- tends to all the other branches of the art of electrotyping as demonstrated by the specimens to which we have already re- ferred.

From a paper upon the present subject, read by Professor Jacobi before the Acade- my of Sciences in Russia, in 1868, it ap- pears that in the previous year M. Feu- quieres sent to the Paris Exhibition some specimens of iron electrotype which pre- sented a fair appearance as regarded sur- face, but still were inferior to those pro- duced by M. Klein in the year following. M. Feuquieres does not appear to have published the process by which he obtain- ed his results, and he, moreover, only spoke of it with the greatest reserve. Professor Jacobi, however, states on the authority of Professor Varrentrapp, of Brunswick, that the process and the bath employed differ essentially from those of M. Klein, whose results may be considered as being perfectly independent.

Referring to the process of electrotyp- ing in iron, Professor Jacobi observes that the good quality of the iron deposit de- • pends principally upon the greater solu- bility of the anode. The augmentation of its surface not having produced the desir- ed effect, M. Klein conceived the idea of combining the anode of iron with another of copper. The Professor varied this combination by replacing the copper with horn charcoal, which gave more powerful results. The effects of this combination were thus rendered complete, the metal negative combined with the iron in the same bath formed a duplicate layer, which worked as a cathode opposite the iron, and as an anode by its combination with the copper wire, or the positive pole of the pile, which furnished the principal curreit. The surface of this electrode consequently disengaged hydrogen and oxygen simultaneously, which combined in proportions which form water. The surplus hydrogen freely disengaged itself, or produced a polarization of the electro- type. If, observes the Professor, the oxy-

gen is most abundant, and if the electro- type consisted of an inoxidable subsbuiee, such as horn charcoal, it would also have disengaged gas, and have given a feeble polarization. If, however, the electrotype is oxidable like copper, it will be oxidized and dissolved. By immersing a galvanom- eter in the circuit, Profes or Jacobi has observed the deviation of the needle di- minish by degrees, whilst the current was very feeble, and it became perfectly still after the force of the current had been increased to a certain degree. At length, passing that degree, the Professor noted that the deviation again became incon- stant. By means of the galvonometer, it therefore becomes easy to so regulate the current as to disengage neither the oxygen nor the hydrogen from the cathode.

So far, Professor Jacobi. Turning now to a letter from M. Klein, which was placed before the Russian Academy of Sciences in 1868, we have recorded the methods employed by him in the produc- tion of iron electrotype. M. Klein saw M. Feuquieres' specimens at the Paris Exhibition, and, encouraged by Professor Jacobi, he, on his retuxm to St. Peters- burg in October, 1867, renewed his at- tempts to electrotype in irOn. The scien- tific interest which attached to the new development, and the eminently useful applications of which he saw it was sus- ceptible, especially in the departments of engraving and printing, stimulated M. Klein, and in the early part of 1868 he had accomplished his object. The medals produced in the early part of M. Klein's researches, showed on their reverse, poros- ities and deep hollows which penetrated nearly through the thickness of the de- posit. These cavities were also observable in great numbers in the productions of M. Feuquieres. In M. Klein's later speci- mens these singular cavities — which prob- ably proceeded from bubbles of gas — en- tirely disappeared, and their reverses are in no way inferior to those of copper specimens produced under the best con- ditions. The starting point of M. Klein was the steeling of engraved copper-plates, which process was effected in a bath com- posed of the chlorates of ammonia and iron, to which he added a small propor- tion of glycerine. Those, however, who have paid attention to this steeling pro- cess have had occasion to remark that in giving the deposit of iron a greater thick-

16

VAX XOSTCANIVS ENGINEERING MAGAZINE.

ness, the surface cracked, and the deposit detached itself from the cathode in ex- cessively brittle ilakes. It became neces- sary, therefore, to employ baths of two different classes, composed of sulphate of iron and sulphate or chlorate of ammonia. Finally, H. Klein devised three baths after the formulae Fe O, S 03 + N H, O, S 03 -f G H O.

The first bath consists of a concentra- ted solution of crystals of double salt Fe O, S O, + N Hi 6, S03+CHO above mentioned. The second bath was com- posed by mixing the concentrated solu- tion of each of these two salts in the pro- portions of their equivalents. At length M. Klein obtained the third bath by tak- ing a solution of sulphate of iron, precip- itating the iron by carbonate of ammonia and dissolving the precipitate by sulphu- ric acid, getting rid of all excess of acid. In preparing the baths of the second class, M. Klein, as we have stated, mixed the solutions of chlorate of ammonia and sul- phate of iron in the proportions of their equivalents. Another method employed is, to dissolve in a solution of sulphate of iron as much chlorate of ammonia as it will readily absorb at a temperature of about 66 deg. Fahr. All these baths were concentrated as highly as they could be. As an anode, M. Klein employed iron plates giving a surface of about eight times that of the copper cathode. In using a Daniell battery for the decompo- sition the deposit was formed in 24 hours upon the whole of the cathode. The de- posit, however, was full of flaws, and was easily detached and broken up into frag- ments.

As it often happens that the solu- tion of sulphate of copper improves by use, M. Klein hoped that the iron solutions would act in a similar manner. He there- fore continued the experiments for several days without, however, obtaining any bet- ter results. Under the advice of Profes- sor Jacobi, instead of a pair of Daniell cells for each of the five stages of decom- position, he then employed four pairs of feebler Meidinger cells, uniting them in series with the five stages of decomposi- tion. This arrangement was found to give a smaller development of hydrogen at the cathodes and better final results. The deposits, however, were not yet per- fect, some exhibiting porosity and others being furrowed.

Conceiving from previous experience that this was due to acidification of the bath, M. Klein tested it, and found a very decided acid reaction. He attributed this acidification to the circumstance that the quantity of iron deposited on the cathode was greater than that dissolved by the anode. It was therefore necessary to give the anode a greater degree of solubility, and as that could only be effected by in- creasing its area, M. Klein conceived the idea of placing in the bath a plate of cop- per and uniting it with the iron. The result of this combination was very re- markable; not only were the baths of the first class rendered neutral after several hours, but the deposits became much more uniform. Their color was a dull grey ; they adhered perfectly to the ca- thode without warping or cracking in any part. During the first 24 hours the sur- faces remained perfectly even, but after- wards they began to exhibit minute cavi- ties similar to the appearances often pro- duced upon galvanic deposits of copper. These cavities, however, rarely penetrated to the depth of the deposit. Their pro- duction is attributed to the superabun- dant disengagement of gas on the surface of the cathode. It probably happens that these bubbles attach themselves strongly enough to hinder the formation of the deposit. If the energy of the current be- comes too great, these annoying phenom- ena are produced more frequently. By reducing this energy in the process, and having only an imperceptible disengage- ment of gas by diminishing the concen- tration of the bath, or augmenting the resistance of the solid portions of the cir- cuit, the formation of these cavities en- tirely disappeared, and the beautiful re- sults to which we have already referred, have been obtained. A microscopical ex- amination of the reverses of the deposits produced by M. Klein's final process fails to discover any porosity or irregularity in the specimens.

On leaving the bath the iron is as hard as tempered steel and very brittle. Re- heated to a dull red heat it loses much of its sharpness and hardness. Heated to a cherry red it becomes malleable, and may be engraved as easily as soft steel. If the deposits are produced in good con- dition, and annealed uniformly and with the necessary precautions, they are nei- ther subject to warp nor bend. There is

IRRIGATION V. DISINFECTANTS.

17

no contraction, but on the contrary, a slight degree of expansion, almost imper- ceptible, however. Owing to the necessity of having bank-note and similar plates identical in every respect, it is of the first importance that they should not be dis- torted nor have their dimensions altered in the process of annealing. It appears that the galvanic deposit of iron has not only permanent magnetism, but that, like soft iron, it receives the magnetism of po- sition.

We have now received both the failures and the successes of M. Klein. Of the importance of the practical application of the process, there can be no doubt what- ever. By replacing plates of copper by those of iron, greater facilities will be af- forded for producing publications, works

of art, and especially bank-notes and checks. Iron electrotype plates are found to be almost indestructible. They not only can be printed from an almost un- limited number of times, but they are bet- ter calculated than those of copper to withstand those inevitable accidents con- stantly occurring in printing establish- ments. Printers are sometimes obliged to set aside as useless their best plates, which are often damaged by a grain of sand, or by a chance knot in the paper. These accidents not only involve the ex- pense of renewing the plates, but some- times occasion interruptions and delays in works of a very pressing nature. These are some amongst the many which may be expected to accrue from the introduction of iron electrotype.

IERIGATION v. DISINFECTANTS.

From "The Enginasr."

Ever since the commencement of the sewage difficulty, the rival claims of the irrigation and disinfectant partisans have been prominently placed before the public ; yet the problem is still unsolved. The results of irrigation are tangible and appreciable ; so also, it is said, are those of the deodorizing and disinfecting sys- tems. Our own opinion on the respective advantages of the two are too well known to require any recapitulation on our part. The whole subject is now on its trial, and until the experiment which is being con- ducted with regard to the sewage of the metropolis is a success or a failure, all criticism may be fairly suspended. The task which the Native Guano Company have undertaken to accomplish at Cross- ness differs in no respect from that which has always constituted hitherto the insu- perable obstacle to a satisfactory solution of the important question. It is not in- trinsically of an arduous character. It involves only two conditions. The one is the purification of the effluent water; the other the utilization of the solid residue. Both of these must, however, have a refer- ence to some standard. The former ought to attain to that prescribed by the Com- missioners appointed to inquire into the pollution of river3. Perhaps this is of a rather stringent character. One thing is nearly certain, viz., if the Conservators of the Thames elect to adhere to this stand- Vol. VI.— No. 1—2

ard, there will be an end to the experiment to which we have alluded. There is no difficulty in purifying the metropolitan sewage to an extent which will allow the effluent water to pass into the river in a state of almost absolute purity compared to the filth which is at present pumped into it. It remains to be seen if the Board of Conservancy will be content with an amelioration instead of a cure of the evil. That the result of the forthcom- ing experiment will very materially im- prove the present condition of the sewage discharged into the Thames, we have not the slightest doubt. That it will not purify the effluent water so as to bring it up to the standard of the Rivers' Pollution Commissioners, we have also not the slight- est doubt. But between this standard and that which will probably satisfy the Con- servators there is, fortunately for the ex- perimentalists, a wide margin. So far as the pollution of the Thames is concerned by metropolitan sewage, the term applied to its guardians is a complete misnomer. They are able to hold their own with the small fry, but when they have to tackle a big fish, such as the Metropolitan Hoard of Works, they are nowhere. They give no mercy to the riparian small towns and villages situated beyond the nmnicipal boundary, and yet allow the whole sewage of the metropolis to be discharged into the river they are px*esumed to conserve.

18

VAX XOSTRAND'S ENGINEERING MAGAZIXE.

It may be assumed that with respect to i the Thames the first condition of the sew- age question may be considered to be ! partially fulfilled. In other words, the I effluent water which will be subsequently I discharged into the river from the new : works in course of erection at Crossness, will be comparatively so pure with respect , to that which has hitherto been pumped into the stream, that it will be considered j to leave nothing to be desired. The proof of its actual purity will be the analysis of it, which there is no doubt will be undex'- taken by competent authorities. There now remains the second part of the ques- tion to be taken into consideration. It involves the manufacture of the salable manure, and collaterally the cost of its p "oduction. It is this part of the plan tuat is to pay for the whole operation, and recoup the shareholders for the money they have expended. There are a great variety of opinions respecting the manure made from the solid residue of the purified effluent sewage water. It is asserted that it commands a high price in the market, and is eagerly sought for by agricultur- ists, while some maintain that it will bare- ly pay the expenses of cartage. It should be borne in mind that the mere fact of a manure rich in manurial ingredients being manufactured from sewage residue, is no test of the financial success of the process by which it is produced. Nothing is easier than to make a rich and valuable solid manure. All that is required is to put the necessary ingredients in, and the thing is done. Nothing more is necessary than to combine the manurial elements with the actual sewage residue, and then say there is a valuable solid manure man- ufactured from sewage. But really to ef- fect the object in view in such a manner as will pay the cost of manufacture is to prepare the manure from the sewage, and from the sewage alone. It is here that the uncertainty prevails. What propor- tion of the manurial value of the solid ma- terial is due to the sewage, and what to the ingredients purposely combined with it, the value of which latter is previously well known ? Chemists and analysts can ascertain the composition of a manure, and from that assign its theoretical agri- cultural value. But the farmer is the person who really determines the practi- cal, that is, the profitable value of the manure, and on this point chemists and

farmers differ very widely. If the material prepared in the manner described derives its value, not from the sewage, but from certain ingredients mixed with it, the utili- ty of which is recognized by all, the farmer may as well purchase those ingredients in some other shape. There is obviously no gain in buying a lot of dirt to act merely as the vehicle for a comparatively small quantity of genuine manure.

We, as well as everyone else, are waiting with much interest the result of the trial at Crossness, for there is not the slightest doubt that,omitting all consideration of the irrigation system of utilization of sewage, the general question very much depends upon the success or failure of the opera- tions which are to be carried out there. With the exception of the A. B. C. scheme, all the others of a similar nature, having the same end in view, have, from one cause or another, gradually fallen through. That one alone, notwithstanding the vigorous and perhaps rather severe condemnation passed on it by the Rivers' Pollution Commissioners, has kept its head above water, and attempted a solution of the great problem on a scale of magnitude commensurate with its importance. In- deed, to judge from the market price of the shares of the Company, it ought to be the most profitable investment open to capitalists. Our own views on the subject of the utilization of sewage have been so often expressed that we need not recapitu- late them. While still adhering to those opinions, and believing that the irrigation principle is the best, we should neverthe- less be rejoiced to witness the success of the experiment at Crossness. But the trial must be complete in eveiy sense. It will not be sufficient to establish that a portion of the metropolitan sewage can be treated successfully for a brief period. It must be demonstrated that the method is capa- ble of dealing with any quantity for any length of time continuously. Were the system once in active operation, a break- down would be an event of the gravest moment. The flow of sewage is incessant day and night, and the means for provid- ing for its treatment must be also always available. This is a difficulty not to bo despised, even when it is confined to small towns, but it becomes very formidable when it assumes the proportions resulting from its connection with a city of the size and population of the metropolis.

STRAINS IN STRAIGHT GIRDERS AND TRUSSES.

19

STRAINS IN STRAIGHT GIRDERS AND TRUSSES.

By E. SHERMAN GOULD, C. E.

I. STRAIGHT BEAMS AND GIRDERS.

A. Horizontal St,rain&.

Let us consider the effect of a weight placed upon the centre of a beam, resting on two supports.

It is evident that each support sustains one-half of the weight. The principle of reaction permits us to consider the beam as being pressed upward at each end with a force equal to the pressure on the sup- ports, against the weight at the centre, considered as a common fulcrum.

This force acts with a leverage equal to half the length of the beam, and tends to crush the beam together at the top and tear it asunder at the bottom. Calling the weight at the centre W, and the length of the beam L, the strain tending to frac- ture the beam may be written W . L _AV L'j 2 ~~ 4

^X

This is the strain tending to produce rupture at the centre. It is constant for a given weight and length of beam, irre- spective of the shape or material of the beam. It is resisted at the centre by the strength of the material of the beam, mul- tiplied by its depth at the centre.

This must be further elucidated. We have seen that the weight tends to com- press the top of the beam and extend the bottom. It is clear that there must be some point in the strained section where the character of the stress changes, that is, where it ceases to be compressive and becomes tensile, and vice versa. This point is assumed, in a straight beam, to be at the centre of its depth. Around this point, under the influence of the weight, the beam tends to turn with a.

W L force equal to — - . Thus

Fig. 1.

To this crushing and extending force the material of the beam opposes a cer- tain resistance, which is the more effec- tive as the depth of the beam, and there- fore the leverage with which it acts, is greater. In effect, the system of strains and resistances, as shown above, consti-

W tutes two bent levers. The force act-

ing with the leverage a b, tends to turn the beam around the point a, while the resist- ance of the material of the beam to com- pression and extension, acting with the respective equal leverages ad and ac tend

* It is of course unnecessary to explain that it is only the moment of the reaction of one support which tends to pro- duce rupture. Should the student have any difficulty in real- izing this, he need only recall the effect produced by two men of equal strength pulling against each other, on a rope. Though both pull, there is no more strain on the rope than if one end were nude fist and only one man wore pulling upon

to keep it in a straight line. It was early seen in the study of the resistance of ma- terials, that the material in the top and bottom edges of a beam was rendered the most effective from the greater leverage with which it acted, and the effort to con- centrate most of the material at those points, led to the introduction of girders formed with top and bottom flanges, joined by a web. As certain materials resist one hind of strain better than they do the other, the scantling of the flanges is proportioned with a view to establish- ing an equality of resistance at top and bottom.

Thus we have

force . — tending to

turn half the beam, around the point a, resisted by a certain factor R (the resist- ance of the material to compression) mui-

20

VAN NOSTRAND'S ENGINEERING MAGAZINE.

tiplied by a c, phis a factor R' (the resist- ance of the material to extension) multi- plied by a d. But the girder is, as we have seen, so constructed that R=R', the re- sistance of the girder is therefore R (a c-f- a d). But a c-\-a d=D, or the depth of the girder at the centre. We have then, for the resistance of the girder at the centre,

r r>.

In order that the girder may sustain the weight, it is necessary that this force be at least equal to that tending to pro- duce rupture. That is, we must have

4

From which we obtain

tt-WL-

E-ID.

Example. — What is the value of R for a wrought-iron girder, 1 ft. deep from cen- tre to centre of flanges, resting on two supports 12 ft. apart, and bearing a weight of 12 tons, placed at the centre?

Here

12 x 12

K=-=

4X 1

= 3G tons.

Taking the safe resisting strength of wrought iron to crushing and tearing* at 5 tons per sq. in., the flanges of the above girder must have a section of 7.2 sq. in.

The above formula gives the strain at the centre of the girder. To obtain the strain at any other point, we must substi- tute the distance from that point to the

nearest abutment, for — in the formula. •a

That is the strain at any point in the flanges of a girder supported at both ends and loaded in the middle, is equal to the reaction of the supports multiplied by the distance of the given point to the nearest support. If in the above exam- ple we wished to find the value of R for a point half way between the centre and one of the supports, we should put

R =

12 X 3

2~

= 18 tons.

If the load be applied at a point other than the centre, the weight borne by ei- ther support is to the whole weight as the distance from its point of application to the other support is to the whole length

* Though the resistance of wrought iron to a tensile strain is considerably greater than its resistance to compression, it is found in practice, particularly with riveted flanges, that it is not safe to use a smaller section at the bottom than at the top.

of the girder. Thus, in our example, if W be placed half way between the centre and the right support, the weight sus- tained by that support is f W = 9 tons, and the weight sustained by the left sup- port is |W = 3 tons, the sum of the two making up the whole load. The moments of the reactions of the supports around the point of application of the load are equal. Thus in the above, f W X \ ^-'==\ WXfL. The strain at this point is there- fore given by either side of the above equation.

The strain at any other point is equal to the moment of the reaction of the sup- port between which and the applied weight the given point is located, around such point. This is an extension of the rule enunciated in reference to a central weight. If, in our example, W be placed 3 ft. from the right support, the value of R for a point 3 ft. from the left support is

W L

-^-X -£- =9 tons.

It will be seen in all cases of a single weight, that the maximum strain occurs at the point of application of the weight.

Let us now consider the case of a girder supported as before, but over which the weight is evenly distributed.

Fig. 2.

omooococoaD

-m, — *«•- 0

I

As far as the pressure on the supports and the strain on the flanges at the cen- tre are concerned, Ave might consider the weights as being concentrated in equal groups about the centres of gravity of the two halves of the girders, thus :

Fig. 3.

Each support bears half the weight, that is the right support bears | of the right half weight and J of the left half

W weight, making — in all, and the same 2

STRAINS IN STRAIGHT GIRDERS AND TRUSSES.

21

reasoning applies to the left support. The strain at the centre is obtained by calcu- lating the separate action at that point of each half weight, and taking their sum. Thus, the reaction of the right support

-W

0t2> the strain which that half weight exerted

from the left half weight being \

w

at the centre is rr X

The other

LL_\VL

8 'N 2 16 '

half weight exercises an equal strain at same point, and the sum of these

the

the WL

We have

gives a total strain of therefore, in the case of a girder so loaded, for the central strain, which is

K =

S D

half that produced by an equal weight concentrated at the centre.

By taking the strain at other points be- tween the two weights, we find it equal throughout the central segment.* This fact precludes the using of this transfor- mation of the weights in determining the strain at various points in a girder uni- formly loaded. It is always possibb, how- ever, to ascertain the strain at any given point in a girder so loaded, by supposing the weights grouped at the centres of gravity of the segments into which such point divides the girder. Thus, to deter- mine the strain at a point distant m from the left support (Fig. 2), we might con- sider the weights on each side of a b as concentrated at the centres of gravity of their respective segments, viz. : the weights

m

on m concentrated at — and those on n at

2 n — . Reasoning as for the strain at the

centre, we should find the strain at a b due to the weights on

m W m = — — X

Xn

W

and that due to the weights on

W n2 to

2L2 Adding, we have,

,yy-j <jn n + n2 to)

for the actual strain at a b.

But this method of reasoning leads, as we see, to a rather complicated formula.

* We may therefore obtain the strain throughout that portiou of a girder comprise! between two equal a:id symmetrically placed weights, by taking the moment of the reaction of on 3 of the supports around the point of application of the weight nearest to it.

It is better to treat the question in the following manner : "We have, as in the case of the girder loaded at the centre, the

W reaction — of the right support acting

upward with the leverage n. In the pres- ent case however, we have a certain amount of resistance to this strain, due to the distributed load upon n, and inde- pendent of the resistance of the girder itself. That is to say, the loaded seg-

Vf.n ment n acts against the upward force -%

to the extent of the moment of the weight upon its centre of gravity around the

given point. The weight on n is — ths of

W. The strain and resistance at a b are therefore expressed by the equation

ED =

W

Wn

X

whence

R =

W

2i)

(n-n2)

W

= ,7?T7-CLx-a:2)

JL 2 D Lv

In the last expression x has been sub- stituted for n, as either of the segments m and ?i gives the same result.

If the above equation be resolved for the value of D, and R be made constant, the successive values, D, will vary as the ordinates of a parabola.

The previous problems, where the strain at any point is ascertained by the reac- tion of that support between which and the weight the given point is located, may also be resolved, though not so read- ily, by taking the moment of the reaction of the ether support, less the moment of the loaded segment, as in the present case.

The maximum strain, when a girder is uniformly loaded, is at the centre. When the girder is loaded with a single con- centrated weight, the maximum strain is at the point of application of such weight. If now a girder be at the same time subjected to an equally distributed load, and a single weight placed at some point other than the centre, the position of the point of greatest strain as deter- mined by either one of these loads con- sidered separately, will evidently be mod- ified by the action of the other. The maximum strain in the flanges of a girder, however loaded, occurs at the point which forms the centre of equal moments of the reactions of the twro supports. Therefore, to obtain the point of greatest strain in a

VAN NOSTRAND'S ENGINEERING MAGAZINE.

girder bearing two loads, one uniformly distributed and the otber concentrated at a single point, we must find the total re- action of each support from both weights, and then determine that point in the gir- der around which the moments of the same shall be equal.

Suppose, for example, a beam loaded with the equally distributed load TV, and also with a single weight equal to W placed midway between the centre and tbe left support. The reaction of the left

W support is —-from the distributed, and f

W from the undistributed load. Total reaction of left support f W. The total reaction of the right support is found to .be f W. Let L represent the length of the beam and x the distance of the centre of equal moments from the left support. • Then £ W x = -£ W (L - x), whence * = #L.

B. Vertical Strains.

So far we have considered only the strains in the upper and lower edges or flanges of a beam or girder, and in the case of a solid beam, these horizontal strains, as they are called, are the only ones of which it is necessary to take ac- count. But when a girder is formed of flanges joined by a comparatively light web, it becomes necessary to ascertain the vertical or shearing strain, that is, the strain which the web must sustain in "keeping the two flanges apart, in order to proportion the scantling of its parts to the duty it may be called upon to per- form.

These strains are entirely independent of leverage. In the case of a single weight applied to the top of a girder, the tenden- cy is to crush the web with a force equal to the reaction of the supports. Thus, if the weight be applied at the centre, the shearing strain throughout the whole

W girder is -y. If it be applied midway be- tween the centre and one of the supports, the shear on all parts of the web between it and that support is § W, and on all parts between it and the other support JW.

When the girder is uniformly loaded, the case is different. If we consider a girder loaded with 12 equal weights (Fig. 2), it is obvious that the web at the ends of the girder must be strong enough to

sustain the whole 12 weights — G on each end. At the points between the 1st and 2d, and the 11th and 12th weights, it need be only strong enough to sustain the 10 intermediate weights, and so on to the centre, where the shearing strain is niL Therefore, in a girder uniformly loaded, the shearing strain at any point is equal to the weight on that part of the girder comprised between the centre and the given point, and this strain is the same at the corresponding point on the other side of the centre. We see by this that the point of maximum horizontal strain cor- responds to that of minimum vertical strain, and vice versa.

There is a curious phenomenon con- nected with the shearing strain of an equally, as compared with that of a par- tially loaded girder. One would suppose that the greatest strain of this nature at any section, a b (Fig. 2), would occur when the whole girder was loaded throughout. But such is not the case. If the 3 weights to the left of a b be removed, the shear at a b will be augmented. To investigate this phenomenon, let L represent the whole length of the girder ; w the weight per unit of length (that is the weight per foot, yard, or whatever unit is used in L); n the segment of L bearing the load; m the unloaded segment. Referring to Fig. 2, to get the shearing strain at a b when the 3 weights on m are removed, we may sup- pose those on n concentrated at its centre of gravity, and calculate the weight sent by them in this position to the left sup- port, which will be the shearing strain at a b and throughout the unloaded seg- ment.

n

The centre of gravity of n is -n~, and the

weight on n is n W. Accordingly, the

weight carried by the left support, would

n n'2 W

be the half of jj ths of n W, or -^j

which would be the shearing strain sought for. If now we replace the 3 weights on m, so that the girder becomes entirely covered. We find the shearing strain at a b to be

w (m + n ~ m> or W (n~m)-

Subtracting this from the strain at the same point when the girder is partially loaded, we have

W

2L

W

(n~ m)

2^L

= ttt~" ^2 ~*J ?l + L m).

STRAINS IN STRAIGHT GIRDERS AND TEGSSE3.

23

But n2 —Tin -\-Jj m = m2, so the excess of strain at any point of a girder when only the longer of the two segments into which it divides the girder is loaded, over the strain at the same point when both W m2

segments are loaded = '

2 J j

It seems a little difficult to realize that a strain is actually augmented by a reduc- tion of weight, and if experiment were not at hand to verify theory in this matter, one could hardly accept the fact.

For a further discussion of this point, see Stoney on Strains, Yol I., p. 30.

II. STRAINS IN STRAIGHT TRUSSES. .

"We have now considered the strains produced in a beam or girder supported at both ends, under all the circumstances of loading wThich can ordinarily occur. We will proceed to investigate the effect of these strains in bridge construction.

A bridge truss may be considered as a large girder, and when the web is formed of plates or riveted latticing, the strain at any given point is ascertained by the direct use of the formulas already given. When, however, the web is formed by trussing, the varied disposition of the different members constituting the truss, renders the calculation more complicated; for in determining the strain upon any member of the web or truss, it is neces- sary to ascertain precisely what amount of the weight is sustained by that mem- ber, and in finding this strain for any given point, it is often necessary to take some other point, more or less distant from the one actually in question, as that which determines the loaded segments.

The first effort to most effectively dis-

pose of a given amount of iron in the con- struction of beams, led, as we have seen to the introduction of the flanged plate girder, of which the tubular system is only a special adaptation. It was soon found, however, that this system, as ap- plied to bridge construction, failed to permit of a proper depth between the flanges, as the thin plates composing the web, yielded by buckling, when their depth was considerable. To obviate this, the lattice girder was introduced, which may be regarded as a plate girder, the web of which has been folded into narrow strips, and these placed diagonally be- tween the flanges. The result of this ar- rangement is, that while only the same amount of material is used, it is so dis- posed as to yield less readily to lateral flexure. Still further efforts to increase the concentration of web material, led, with other considerations, to the various kinds of triangular trussing now in use.

The strains on bridges are due to two causes: — the weight of the bridge itself, which acts as a uniformly distributed load, and the weight of the train, which, in itn passage over the bridge, develops all the strains we have already investigated.

One of the simplest forms of bridge truss, is that known as the Howe. This truss is composed of top and bottom chords, vertical ties, and inclined braces and counterbraces.

We will suppose a truss constructed on this principle, 200 ft. long, 18.75 ft. effec- tive depth, with the vertical ties 12.50 ft. apart. The truss is thus divided into 16 panels. The roadway rests on the bottom chord. One half of such a truss is shown in the figure.

Fig. 4

We will assume the weight of the bridge itself to be 160 tons of 2,000 lbs., and the weight of a train of locomotives completely covering the bridge to be 320

tons. As we will conduct our reasoning upon a single truss, we must take half of these weights only in our calculations. The length of a panel will be taken as the

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VAN NOSTRAND'S ENGINEERING MAGAZINE.

unit of length. We have therefore the following symbols and values:

L = length of truss = 10.

T> = depth of truss = 1.5.

W = weight of loaded truss= 210 tons of 2000

lbs. to = panel weight of truss = 5 tons of 2000

lbs. id' = panel weight of load = 10 tons of 2000

lbs. to"=(W + W) — 15 tons of 2000

lbs.

"We will first calculate the horizontal strain in the lower chord, at the end of each panel, beginning at the one nearest the abutment. This strain is maximum when the bridge is covered with its load, and is constant throughout each panel length of the chord. We make use of the formula

which we resolve for the successive values

W of x from 1 to 8. The constant 2 _p r 5,

and we obtain from the formula the fol- lowing values for K : 75, 140, 195, 240, 275, 300, 315, 320. We check by apply-

L W ing the formula It = — - for the central

8 D

strain, which gives 320 as above. The strain in the top chord is obtained by tak- ing successive values of x from 1 to 7, so that the strain in the first panel of the top chord is the same in that in the first panel of the bottom chord, and so on, the strain in any panel of the top chord being the same as that in the panel of the bottom chord next nearest the abutment.

To determine the shearing strain upon the ties and braces (the counterbraces will be spoken of hereafter), it will be nec- essary to ascertain in what way the weight is borne by these members. The top chord is kept at the proper distance from the lower one by the braces, and the lower chord with the load is suspended to the upper one by the ties. In this way the whole bridge and load are suspended by the ties to the braces, which may be considered as cranes or derricks.

We have found that the maximum shearing strain at any point occurs when only the longer of the two segments into which it divides the length of the truss is covered with the rolling load, and we have found the amount by which this maxi- mum strain exceeds that produced at the same point when the whole bridge is cov-

ered by the load. We will therefore de- termine the strain on each tie and brace when the bridge is uniformly loaded, and then add this excess.

When the bridge is entirely covered, the whole weight of the 7 loaded panels between the end tie and the centre, is carried by that member, and by it trans- ferred to the end brace. But, besides this, it carries half the loaded panel between this and the abutment, the other half be- ing carried by the abutment. The total weight sustained by the tie,and by it trans- ferred to the brace, is, therefore, that of 7.5 load panels. In like manner, the sec- ond tie and brace carry G.5 panels, the third 5.5, and so on to the centre tie, which carries 1 panel, that is, half a panel from each side of the centre, while the centre braces carry only half a panel each, as they sustain the tie between them. Multiplying these coefficients by W", we have for the tensile strain on each tie from the first to the centre, produced by a uni- formly distributed load, the following values: 112.5, 97.5,. 82.5, 67.5, 52.5, 37.5, 22.5, 15.

We obtain the proper augmentations "W * from the formula y^™2, m being the un- loaded segment at any point. In using this formula, it is important to ascertain the proper values to ascribe tow. In the present case, to obtain the augmentation for any given tie, we suppose the entire panel between it and the nearest abut- ment, covered with the rolling load which reaches thence to the furthest abutment. Half of this panel weight is born by the tie in question, and half by the tie next nearest the nearest abutment. The value of m for any tie is, therefore, the distance from the nearest abutment to the centre of the panel which the given tie closes. In this case the successive values of m are, 0.5, 1.5, 2.5, etc., up to 7.5. The value

of the constant 21,= 0.3125, which multi- plied by the squares of the above coeffi- cients, gives the proper increment to be added to the values already obtained. We have thus far the maximum strains on the ties, 112.6, 98.2, 84.5, 71.3, 58.8, 47, 35.7, 32.6.

In a beam or girder, when m = —^- the

strain produced by the applied load equals £th of inch. If we applied thia

STRAINS IN STRAIGHT GIRDERS AND TRUSSES.

25

rule to the present case, we should get a strain of 20 tons from the applied load, which, added to 4 tons from the perma- nent load, would give a total of 25 tons for the maximum strain on the centre tie. By the construction of the truss we are now considering, this amount is exceeded by half a loaded panel.

The strain in the braces are deduced from those in the corresponding ties by multiplying the latter by the secant of the angle which the braces make with the ties. That this gives a correct result is easily demonstrated by the resolution of forces. The secant is obtained by di- viding the length of the brace by that of the tie. In the present case it equals 1.2 ; we have then for the maximum strains in the braces the values 135.1, 117.8, 101.4, 85.6, 70.6, 56.4, 42.8, 30. These strains are compressive.

We have now to investigate the subject of counterbraces, which are struts sloping in a direction contrary to that of the braces. In virtue of .this definition, the braces of one half of a truss are counter- braces as regards those of the other half, the change of direction taking place at the centre of the truss, at which point the two middle braces abut against each other. If the truss be uniformly loaded, the centre is the point at which the great- est horizontal strain takes takes place. In a truss so loaded no counterbracing is necessary, and this fact points to the rule governing counterbracing in all cases.

Under all circumstances of loading, it is at the point of greatest horizon- tal strain that abutting braces or counter- braces, throwing the shearing strain right and left towards the two abutments, are needed. It has been already estab- lished that this point corresponds to the centre of equal moments of the reactions of the two abutments. When the bridge supports only its own weight, this point is at the centre. But the passage of a train, by unequalizing the reaction of the abutments, causes this centre of equal moments to shift from the centre of the truss. The point is now to ascertain how far it is possible for the weight of the passing train to cause this point to move from the centre of the truss, for beyond this point it will be unnecessary to pro- vide counterbracing to resist the shearing strain. Let us examine the action of a

train which advances upon the bridge, covers it throughout and moves off again. As the head of the train gets on the bridge, proportional parts of its weight go to each abutment and are added to the re- action of the permanent load. As these reactions are now unequal, they change the position of the centre of equal mo- ments, which moves from the centre of the truss to a point nearer the advancing train. Counterbracing now becomes ne- cessary as the train advances ; the centre of eqiial moments advances to meet it, carrying the necessity for counterbracing with it. When the head of the train reaches the centre of the bridge, the counterbraces begin to be relieved in an inverse order to that which governed the progress of their compression, the one nearest the centre being the first and last compressed. When the bridge is entirely covered, it relapses into its pre- vious condition of uniform loading, only with a heavier load. As the rear of the train gets on the bridge, the centre of equal moments begins to move forward from the centre of the truss in the same direction as the train, until the rear of the train reaches the centre of the bridge. From this time the centre of equal mo- ments recedes again towards the centre of the trus^. On this side also the counterbrace nearest the centre is the first to be compressed and the last to be relieved.

Bearing these considerations in mind, it is very easy to determine the last point at which counterbracing is necessary to resist a shearing strain. We suppose one half of the bridge to be covered with the rolling load, the weight of which is sup- posed concentrated at the centre of grav- ity of the half truss. The total reaction of each abutment is then ascertained, and the centre of equal moments calculated. Between this point and the nearest abut- ment, no counterbracing is required to resist the shearing strain. In our example, the reaction of each abutment from the truss alone is 40 tons. If half the bridge be covered with the rolling load, the abut- ments will bear an additional weight of 80 tons, of which 20 tons will go to one, and 60 to the other. Adding, we have 60 tons and 100 tons respectively for the reactions of the abutments. The equa- tion for equal moments is therefore x 100 = 60 (L — a,'), whence x = 6. That is,

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VAN NOSTRAND'S ENGINEERING MAGAZINE.

the last counterbraces are required at the distance of G panels from each abutment, in our example, which would give two counterbraces on each side of the centre of the truss.

The amount of compressive strain in these two counterbraces, is determined by the following considerations, which, as they involve some of the most important principles of bridge strains, should be closely followed. Under the action of a uniform load, these two members would sustain no compression; on the contrary, if they were so attached to the chords that they could act as tension members, or ties, they would sustain a tensile strain, the one nearest the abutment, a b, sustain- ing one and a half panels, and the other one, c d, one half of a panel. If we sup- pose half the truss to be covered with the rolling load in the manner mentioned, its weight would tend to compress the two counterbraces. But no member of a truss can at the same time sustain or tend to sustain tension and compression, and when both are brought to bear upon it, the actual strain sustained is the differ- ence between the two. Thus, if a certain member was subjected to a strain of 10 tons in tension, and 20 tons in compres- sion, the actual strain sustained would be 10 tons compression. In the present case, the permanent truss weight brings a ten- sile strain of 1.5 w on the first, and 0.5 w on. the second counterbrace, and we must see what compressive strain the weight of the train load brings upon them, and take the difference as the actual strain. To do this, we must take each panel weight of the rolling load separate- ly, and ascertain its effect upon the mem- ber in question, the sum of these separate strains being the total compression on the counterbrace.

Each tie sustains one panel weight of the rolling load = \V\ The first panel weight (W1) on the tie nearest the abut- ment, sends yV^h or -r1 °^ ^s weight

through the truss to the other abutment. 2 3

—, the third, — - , the

13.12 tons. Subtracting the ten-

The second sends

4 5

the fourth — -, the fifth, —-,, and the sixth

of its weight through the truss in the

L

same way, and these all act compressively upon a b. The sum of this series is

21 W

~ir~

sile strain of 7.50 tons, we have a net compression of 5.62 tons on a b. For the strain in c d, we must take one more term

28 W of the series, and we have ■ — - — = 17.C0

tons. Subti'acting the tensile strain of 2.5 tons gives a net compression of 15 tons on c d. These values must be multi- plied by the secant of the brace angle.*

The above investigation shows at what points counterbraces are required to resist the shearing strain of the travelling load. There are other considerations, however, which seem to point to the expediency of counterbracing a truss throughout. There are two qualities requisite in a bridge — strength and rigidity. So far we have considered only the former, though the latter is scarcely less important in struc- tures which, like those in question, are destined to be permanent within the limits of natural decay. All trusses of long span tend more or less to deflect, and if any such structure be designed to sustain a permanent load only, its deflec- tion is generally a matter of but little moment. But when, as in the case of a railroad bridge, it has besides to sustain a travelling load alternately applied and withdrawn, the case is different, for the deflection of the truss under the applica- tion of the weight, is followed by an up- ward spring on its withdrawal. In other words, the tendency of the rolling load is to induce play, which in a built struc- ture leads to shocks at the joints, which become eventually loosened and unser- viceable. When a truss deflects ur.der weight, the panels are distorted from their original rectangular shape into lozenges, by the sliding of the chords upon the web, like a parallel rule. This distortion cannot occur without the braces yield by crushing or flexure, for the diagonal of the lozenge in the direc- tion of the brace is shorter than that of the rectangle which it originally formed.

* The strains produced in these members by the rolling load, may also be determined as follows. The weights sus- tained between o b and the end brace ef = 6 panels. Of this,

3 5

-^ are sent to the right abutment; therefore the strain on

16

21 W'

a 6 = , as before. The weight between c d and e f =

4 7 panels, of which — go to the right abutment. The strain

_,. ,. , 28W' ■. . on c 0, is therefore — j— as before.

STRAINS IN STRAIGHT GIRDERS AND TRUSSES.

27

The braces are therefore the members of the web which oppose deflection. The ties are unaffected by the change of form of the panels while the counterbraces are loosened, as the diagonals in their direc- tion are longer in the lozenge than in the primitive rectangle. When the weight which caused the deflection is removed, the braces are relieved, and the truss springs back against the counters. If, however, while the weight is on the bridge, the play of the counters be taken up, the truss is prevent- ed from recoiling when the weight is removed, and a great degree of rigidity is secured. If the ties of a Howe truss be shortened by screwing up the nuts, .the whole truss rises to a camber, and

both braces and counterbraces are com- pressed. If sufficient weight be now brought on the bridge, it will settle to a straight line, compressing the braces still more, and relieving the counterbraces. If when in in this position the counter- braces be tightened up by the introduc- tion of some sort of packing, the truss will be held down to the. straight line after the removal of the weight. The strain thus brought on the counterbraces is not cumulative, but is simply that due to one panel weight of the rolling load on each counterbrace throughout the truss, We will now take up some other forms of straight trusses, and see how their dif- ferent forms affect the system of calcula- tion adapted for the Howe.

Fig. 5.

The Warren girder, one-half of which is shown above, is trussed with isosceles triangles. Those members, the tops of which incline towards the centre, are braces, and those sloping in the contrary direction are ties. When the panels are very long they are supported by vertical ties, as shown by the dotted lines in the figure. We will firet examine the case where these are omitted. In either case the strains in the chords are calculated as in the Howe truss, only for the lower chord, the values of x in the formula

should be from 0.5 to 3.5, and for the upper from 1 to 4. The point at which counterbracing ceases to be necessary to resist the shearing strain of the rolling load is also calculated as before.*

When the bridge is covered throughout by the rolling load, the ties and braces, commencing with those next the abut-

• It may here be stated, that this point is obtained for all descriptions of straight trusses, however the web may be constructed, by the same reasoning as that employed in the Investigation of the Howe truss.

menf, bear respectively the weight of 3.5, 2.5, 1.5 and 0.5 loaded panels. The incre- ments of strain due to the displacements of the rolling load, are obtained from the usual formula, by giving to m successive values of 0.5 to 3.5. These values must be multiplied as before, by the secant of the brace angle. The truss is counter- braced by so arranging the ties and braces that they may sustain both tensile and compressive strains. Assuming the same weights and length of truss as before, we find the point up to which the coun- terbracing must be carried, at a distance of 3 panels from the abutment. The brace a c will therefore be subjected to a certain tensile strain from the action of the rolling load. The amount of this strain is expressed by the equation

Sec. 6 (w'(^7+ ~+ -|-) 0.5 W) = 12 tons.

The tie a b sustains the same strain in compression.

When the vertical ties are added, the braces bear more weight than the ties which slope from their tops. The main ties bear respectively weights in loaded panels, represented by the coefficients

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VAN NOSTRAND'S ENGINEERING MAGAZINE.

3.25, 2.25, 1.25, and 0.25, with values for m in the formula for increments from 0.75 to 3.75. Each vertical tie bears the weight of half a loaded panel, which it transfers to the brace from which it hangs. The braces sustain, therefore, weights of 3.75, 2.75, 1.75, and 0.75 loaded panels, with increments obtained by giving to m successive values of 0.25, 1.25, 2.25, and 3.25. The compression on the tie a b from the rolling load is 15 tons as before.

We have now to consider a class of trusses known as compound trusses, in which the web is composed of two or

more systems of trussing, crossing each other, hi calculating these trusses, the formula employed so far for determining the strain in the chords is inapplicable without a degree of modification which would render its use tedious. The meth- od employed by Mr. Stoney (Stoney on Strains, vol. i., p. 84) is probably the best that can be used in such cases. He de- duces the strain in the chords from the vertical strain in the inclined members of the web, and as his system is equally ap- plicable to simple and compound trusses, we will first investigate it in reference to the Howe truss already calculated.

Fig. 6.

The principle of the calculation is this: the strain in the chords consists of the horizontal components of the vertical strains in the inclined members of the web, and is obtained at any point by the addition of all such horizontal compo- nents as occur between the given point and the nearest abutment. These hori- zontal components are obtained by multi- plying the vertical strains by the tangent of the angle 6 which the inclined members make with the vertical; as the maximum strain in the chords occurs when the bridge is covered with the rolling load, the first step is to ascertain the amount of vertical strain on the braces when the truss is so loaded, and to write it down upon a sketch of the half truss, as shown in Fig. G. Keeping the same weight and dimensions as before, we find the value of the constant w" y^tsmg. 6 = 10 tons. We write the horizontal component of each brace strain, obtained by multiply- ing the vertical strain by the constant 10, at its apexes, and by successive additions determine the strain in each panel length of the top and bottom chords, as shown in the figure. The results agree with those obtained by the calculation by mo- ments.

We will now take some of the leading styles of compound trusses, beginning with the Linville.

This truss is composed of two systems of triangles, crossing each other, as in the figure, which shows half the truss. Each system bears half the strain which would come upon it if it alone formed the whole trussing. We will assume a truss bearing the same weight as before, and of the same dimensions, except that the depth shall be 25 ft. In the figure, one system of trussing is drawn with heavy lines merely to distinguish it more plainly from the other. The upright members are posts or braces, the inclined, ties.

The vertical strain on each tie is ascer- tained by taking each system separately, and supposing it to sustain half weights. It may also be done by a direct estimate, thus: The first tie from the centre, of the heavily marked system, bears obviously the weight of half a panel, that is, half the weight of the segment of the lower chord, comprised between its foot and the centre post. The other half is borne by the neighboring tie of the light lined system. This last bears besides half of the seg- ment between its foot and that of the heavy lined post next behind it. These

STRAINS IN STRAIGHT GIRDERS AND TRUSSES.

29

two halves constitute the one panel allot- ted to it in the figure. The next heavy lined tie bears the other half of this panel plus the half panel next behind it, plus the half panel transmitted to it through the heavy lined post which rests on its foot. The next light lined diagonal sup-

ports in like manner two half panels, plus the panel transmitted to it through the post resting on its foot, the whole making up the two panels allotted to it in the fig- ure. A similar process of reasoning veri- fies the rest of the weights allotted in the figure.

Fig. 7.

The angle 6 being of 45 deg. tang. 0=1, and the constant tang. 6 w''=15 tons. The end ties of both systems are connect- ed with the end post, as shown in the figure. The tie bearing 3.5 loaded pan- els transmits a horizontal strain of 3.5 X 15 = 52.50 tons to the first panel length of the upper chord, while that bearing 4 panels transmits only 4 X 7.5 = 30 tons, to the same member, its tangent being only 0.5. The additions are made as by the figures.

The maximum strains on the ties and posts are found by considering each truss

separately. Thus, for the ties in the heavy lined system, we have in the for-

W' m2 mula for increments , w' = 10, L = 8,

and m = successively 0.5, 1.5, 2.5, and 3 5. The increments so obtained are added to the panel weights already deter- mined, and multiplied by sec. 6 for the ties.

There is another method of calculating these maximum strains, which may some- times be useful in checking results ob- tained by the above pi'ocess. This con- sists in ascertaining the strain exercised

Fig. 8.

upon each tie and post by the rolling load when at its position of maximum effect, and adding this to the strain produced by the bi-idge weight. For instance, let it be proposed to ascertain the maximum strain on the post a b and the tie a c. The maximum strain from the rolling load will occur when the truss is loaded from the tie in question to the last tie of the same system, as shown in the figure by the light balls. As each tie of the system to which the members we are considering belong, sustains one half of each of the

panel weights adjacent to it, we may sup- pose the weights resting upon the lower chord to be transformed into those drawn below it in black in the figure. We will now ascertain the amount of shearing strain which each weight sends through the unloaded segment, and their sum will be the maximum strain on a b and a c, from the action of the rolling load. No. 1 sends }£ w' ; No. 2, T8^ w' ; No. 3, T\ id' ; No. 4, T\ w' ; and No. 5, T\ w'\ adding we obtain -£§ w' -\- 1.5 w for the maximum shearing strain in the post. Multiplica-

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VAN NOSTRAND'S ENGINEERING MAGAZINE.

tion by the secant of the tie angle gives that on the tie. An inspection of the above descending progression suggests an easy rule for determining the strains by this me- thod for any tie or post. Take the num- ber of panels in both systems (10 in the present case) in the loaded segment, and make it the first term of a decreasing ar- ithmetical series, of which the ratio is the

number of systems in the truss (2 in the present case). The sum of this series multiplied by the rolling panel load and divided by the number of panels in the truss gives the maximum strain in the given members from rolling load.

A counterbrace is needed in the posi- tion of the dotted line a, 22.5, capable of resisting a tensile strain equal to

Fig. 9.

sec. 6 (to' £ — 0.5 w). The heavy lined tie which it crosses is susceptible of re- ceiving a compressive strain of equal amount. The dotted line b, 15, sustains a tension of sec. d io', and 6, o, an equal compression.

Above is shown half of a lattice girder, 80 ft. long, 5 ft. deep, braced with two systems of rectangular trussing ; load as in previous examples, traversing the lower chord. We assume the following values :

io = 2.5 tons, panel weight of truss.

io' = 5 tons, panel weight of travelling load.

(w -f tc') tang. 6=7.5 tons.

L=16.

Reasoning as before, we get the strains shown on the above diagram. To obtain the maximum tensile and compressive strains on the ties and braces, we may

use either the method by series, or the method by increments, which agree very nearly in their results. In the latter we have L = 8, w' — 5 for both systems, and successive values for in of 0.5, 1.5, 2.5, and 3.5 : for the system, 3.5, 7, 6, etc., and of 0.25, 1, 2, and 3 for the other. The sum- mation of series is operated as usual.

Oounterbracingis needed from the point 2 to the centre. The brace 1.2 sustains a tensile strain of

See,0(^_^)=3.5tanB,

and the brace 0.1 one of sec. 6w'=7 tons.

The above example is the same as that given by Mr. Stoney in his treatise on strains, Vol. I., page 111, with the excep- tion that in his example the load tra- verses the lower chord.

RECENT IMPROVEMENTS IN THE MANUFACTURE OF IRON

RAILS.

From " The Engineer."

The superiority of steel rails to iron, which is now generally proved to consist chiefly in perfect homogeneity of the wear- ing surface of the railhead, causes us to regard with much interest every effort to obtain a similar homogeneity in the man- ufacture of ii-on rails; for, leaving the re- quired safety in steel and iron out of the question, as a matter of absolute necessity for both, it is from the homogeneity more than from the hardness in the steel that

rails of this material derive their excellent results. To prove this in a chemical way, the small amount of carbon, about one- third per cent. , compared with the in- creased stiffness when steel rails are tested under the lever, or ball, of only 25 per cent., as compared with iron rails, leads us to conclude that if ordinary iron rails were made as homogeneous as steel, they would stand very nearly an equal wear and tear. The well-known complaint of

IMPROVEMENTS IN IRON RAILS.

31

lamination and so-called " soft places" in the wear of iron rails proves them an early failure as compared with steel rails, and the increased demand for the latter is, therefore, not to be wondered at. This increased demand seems at present to have exceeded the means of supply, for we are told that the steel rail makers are nearly all full with orders for two years to come ; consequently the railway engineer who requires good wearing rails for heavy traffic is placed in the difficult position of not only having to pay an increased price for steel rails, but also having to wait for them, if he can get them at all.

Fig. 1.

Until the supply increases to meet the demand, Ave must look for a retrogression to superior iron rails from those who can neither afford to pay nor to wait for steel rails. It is these circumstances that bring our attention to a patent rail pile by Messrs. Eichardson and Sons, of West Hartlepool, of which we annex a sketch: —

Fig. 2.

T~~

±J

.-.p.;

rf§^

The annexed diagrams show two meth- ods of forming the rail pile3 No. 2 being

that in universal use, No. 1 the patent pile. It will be seen that the old pile (di- agram No. 2) is, and must necessarily be built upon the slab of crystalline iron which forms the head of the rail, and must be placed in the heating furnace in the same position, viz., the slab on the bottom, which is the coolest portion of the furnace, the fibrous iron uppermost, ex- posed to the most intense flame; and in this position it must remain until the several pieces of iron composing the pile are welded together so as to allow the pile to be turned over. The result of this treatment is, that in many cases the fibre of the flange is destroyed, whilst the head is imperfectly welded, and there is produ- ced a brittle rail with a laminated and consequently bad-wearing head. In the patent pile the treatment is entirely re- versed, the fibrous iron to form the flange being placed on the bottom of the heating furnace, and thus preserved from the in- tense heat which is destructive to fibre, whilst the slab which forms the head of the rail, being placed uppermost in the hottest flames, becomes perfectly welded, and the rail produced possesses the maxi- mum of strength combined with perfec- tion of wearing qualities.

The side pieces A, A, are made direct from the crop ends when cut off from the rail, which adds to the cheapness of make. Large quantities have already been made, with the result of better welding in the rail head and more fibrous flanges, which will give a better wearing rail and no breakages. The patent in itself is of lit- tle novelty, and we could hardly answer for makers being able to hold it, or at any rate share any royalty from it, for there are other works in the North — such as Darlington and Britannia, and Ebbw Yale, in Wales — which have also constructed a a pile charged in the furnace with the slab up, although in a different way, yet with similarly good results.

We consider this one of those practical improvements which is of the greatest im- portance for maintaining a good quality, and therefore worthy the notice and ma- terial support of railway engineers. We should not undertake to say how much more should be paid for such rails as com- pared with those made in the ordinary way, and charged with the slab down, be- cause experience will have to prove the degree of their superiority; but for extra

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VAN NOSTRAND'S ENGINEERING MAGAZINE.

rails made to specification we should cer- tainly recommend it, even should the makers ask 10s. more per ton for inserting this improvement alone. The so-called improvements generally tend to deterio- rate the quality on an increased make and reduced cost of production ; indeed, the history of rail making from the com- mencement up to the present time shows this, for why do we so often hear the re- mark that iron rails made nowadays are not half so good as those made a dozen years back, and nobody can contradict it; but the answer is that those rails cost twice as much as these do now, and speaks sufficiently as to the nature of the im- provement.

The question of mechanical puddling, by which a bloom could be obtained big enough to form the whole rail — or at least the entire rail-head — without any seams from piling iron together, will be looked upon with the greatest interest, and we hope that the commission from the Iron and Steel Institute now in America in- vestigating the process of Danks' rotary puddling furnace will on their return be able to effect changes which will lessen the labor of puddling and improve the wear- ing qualities of our rails. Meanwhile Ave consider the mode of working the rail pile with the slab up to the best next means of obtaining a thoroughly homogeneous rail- head and a tough fibrous flange. We be- lieve the Americans, who now make half the rails they require, have already adopt- ed this mode of working; and indeed, the complaints of English iron rails on some of their roads with heavy traffic are too serious to be overlooked by the rail-mak- ing interest in this country.

The Isthmus of Suez. — An important work on the piercing the Isthmus of Suez is being published in Paris ; it is a detailed description of the works, and of the machinery and plant employed, and of the processes and materials used in the actual construction of the canal. The pro- gramme of this book states that its object is to detail and reproduce by its drawings all the technical elements which were in- troduced in the progress of the work. This is the first time that these elements have been thus grouped, the numerous volumes which have already been publish- ed bearing on the political, picturesque,

or commercial aspects of the work of M. Ferdinand de Lesseps.

It is M. L. Monteil, engineer of the Suez Canal Company, who has been attached to the gigantic undertaking since 11 years, who has undertaken this publication. The text will be as concise as possible ; with the history of the work and the descrip- tion of the drawings it will give in detail all prices, and the performance of each item of the plant. There will be 800 plates engraved on copper, giving drawings in detail of the works and the machinery. The work will be divided into ten series.

1. Towns and encampments. Plans of the maritime and fresh-water canals. Geo- logical sections of the Isthmus, and pro- files of the ship canal.

2. Distribution of fresh water.

3. Jetties, lighthouse, and works of con- struction.

4. Services of transport.

5. The small dredging machines ; the application of the endless bands and spoil distributors.

6. Dredging machines employed in the canal ; spoil boats and lighters.

7. Dredging machines, elevators, etc.

8. Dry cuttings. Wagon and engine shops.

9. Repair shops.

10. Materials for maintenance and lighting.

It will be seen that it promises to be a considerable work. All the materials for the text and the plates are ready, and at present they are being prepared for pub- lication. This work, which will confer lasting honor on its author, is intended to render special service to those engineers who may be called upon to study or carry out great undertakings of public interest analogous to the Suez Canal. But it will interest all those who wish to appreciate the efforts made unceasingly during 15 y ears to open a new route to the commerce of the world. — Engineering.

European Products in Japan — The " Ja- pan Times" says, that in the interior of Japan there are to be found shops ex- clusively for the sale of European goods, and that where few, if any, Europeans have visited or passed through. Soaps, perfumes, clocks, colored engravings, and beer seem to be in general demand, while some shops deal exclusively in tables and chairs after the European fashion.

SEWAGE IRRIGATION.

'^

SEWAGE IEKIGATION.

From " The Engineer."

The chief points to be attended to by agriculturists in a practical sense, if they desire to reap that which they sow, are undoubtedly the manuring of the land, the draining of it, and a skilful and judi- cious rotation of crops. Most farmers understand the first, so long as it does not deviate from the stereotyped methods practised from time immemorial, but, comparatively speaking, few the second and third. Yet, upon an accurate com- prehension of these essential branches of the subject, a due appreciation of their paramount importance, and a regular and systematic adoption of them in practice, depends unquestionably the permanent fertility of the soil. It is true that land is occasionally met with, which, from a peculiar geological formation and other favorable influences of situation, is so exceptionally fertile as to require but little manure. It is not, however, the lot of one farmer in a thousand to have his tent pitched among these prolific oases. In many instances, if the land does not pro- duce the results which may be fairly ex- pected of it, the usual cry is that it wants more manure, when, in fact, it may be already choked with it. Nevertheless more manure is applied, while the other two points to which we have drawn at- tention are scarcely thought worthy of notice, and thus the attempt is made to compensate by the wholesale unscientific application of the one for the total neglect of the others. The soil is stimulated or forced to do that which it would accom- plish spontaneously with a trifling assist- ance, were it treated in a proper and scientific manner. The mania which some farmers have for curing all the evils or shortcomings of land by an unlimited use of manure, was well demonstrated when the utilization of sewage by irrigation was first introduced. Many owners and pro- prietors of land tried the system on a small scale, and, as might be expected, the result was a complete failure. They imagined that nothing more was required than to deluge the land with the new fer- tilizer ; and that magnificent crops would follow as a matter of course. But with one exception, namely, that of grass, mag- nificent crops did not follow, even when Vol. VI.— No. 1—3

the method was tried on a large scale, and by those who understood as much of the principle as was understood at that time. It is very unfortunate that grass should evince such an avidity for sewage, for it has led to a very reckless mode of distribution, which has been adhered to in the case of other crops with the most un- satisfactory results. Had grass crops de- manded the same care and discrimination in the application of sewage as the cereals and roots, the system of sewage irrigation would be in a far more advanced stage, both theoretically and practically, than it is at present.

Hitherto the principle of sewage irriga- tion has been regarded as a superficial irri- gation only, the fertilizing fluid not being supposed to penetrate into the ground much deeper than the roots of the plants and crops growing upon it. Hence arises the great, and it must be acknowledged in some instances, the insuperable difficulty of carrying out the irrigation principle. Obviously a very large area of land is re- quired upon which to utilize the sewage. Without going into the merits or demerits of the various proportions, which different authorities have laid down ought to obtain between the numerical strength of the in- habitants of any given town and the number of acres necessary to utilize the sewage of that town, it may be assumed that the average which places the ratio at 100 people to the acre is a fair one. If a farm were entirely laid down in grass this average would be less than that required; but as experience has shown that the sewage of a town cannot be remunerative- ly utilized by its application to a single crop, it is a correct one under general conditions. Supposing, however, that it could be put at 150 persons to the acre, then, taking the population of a citv at 500,000, over 3,000 acres would have to be devoted to the purposes of sewage utiliza- tion. This quantity of land is not acquir- ed without some difficulty, more especially when it is borne in mind that there are several conditions to be fulfilled with re- spect to situation, levels, and physical con- tours, upon which altogether depends the financial success of the undertaking. As a rule, a certain quantity of land can gen-

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VAN NOSTRAND'S ENGINEERING MAGAZINE.

erally be obtained for irrigation purposes, but this amount is very limited ; and moreover, for many reasons, may not be well adapted to the end in view. Take the case, for example, of a town hung in a hollow, as a vast proportion of towns do. If there are no fields contiguous thereto at about the same level, it becomes neces- sary to pump the sewage up to a certain height before it can flow over the land situa ed at a higher elevation. It must be borne in mind that while we acknowledge these difficulties attendant upon sewage irrigation, which have retarded the devel- opment of the principle in its integrity ever since it was practically applied, they con- stitute no argument against its value, which has been demonstrated too convin- cingly to admit of any doubt in the mind of any disinterested and impartial judge. From what has already been stated, it will be manifest that if the irrigation prin- ciple could be applied to a much smaller area of land than is more generally con- sidered requisite, a considerable gain in every respect would be obtained. It would be not only possible, but easy, to procure a minimum quantity of land in many in- stances where the maximum, or what is now considered the necessary, quantity is unattainable. The problem connected with the utilization of sewage by irriga- tion is to utilize the maximum quantity upon the minimum area of land. It may be urged that this has been virtually ac- complished at Craigintenny for many years past ; but the soil there is of a pe- culiar nature, and not often met with. Besides, the correct definition of the term " utilization" does not signify a mere de- luging of fields of grass with sewage, but the application of it in such a manner as will yield the most remunerative return under the circumstances. It must not be forgotten that the purification of the effluent water is a point to be attended to, as equally essential with the utilization of t le sewage. It is, in fact, more so ; for, as the effluent water must sooner or later find its way into some stream or water- course, care must be taken that the con- sents are not polluted thereby. It has been before remarked that under the present system the sewage penetrates but an inconsiderable depth into the soil; but were it caused to penetrate much deeper, as it would always be in contact with it, .>■( process of purification would still go

on, and the same results obtained, with a considerably less superficial area of soil. In a word, the purification of the sewage would not depend upon the superficial but the cubical contents of the land. This is the plan proposed by Mr. Denton, and it deserves serious consideration at the hands of all those interested in this great question. It will at once be seen that it signifies deep drainage of the land, as it is proposed to allow the sewage to penetrate to a depth of from 4 to 6 ft. before passing off through the drains. This plan pos- sesses several features to recommend it. The first is that a much smaller number of acres will suffice for the purification of the sewage of a town or district ; the second, that deep draining of the soil, so much neglected by farmers, will be im- perative, and the third that the land will be more thoroughly manured than by the present process of superficial irrigation.

The expense of carrying out this method will undoubtedly be greater than the cost of that now in use ; but, provided the undertaking pays, that is not an insupera- ble obstacle. Neither would the cutting of the trenches and the laying of the ne- cessary pipes be so difficult or so expen- sive a matter as might at first appear. Messrs. Fowler have machines expressly designed for these purposes. Their pat- ent " knifer" will open ground at almost any depth ; and in heavy clay soils, where it is not advisable to bring the subsoil to the top,the machine can be driven through the ground without materially disturbing the surface. The next operation, that of laying the pipes, could be accomplished with equal facility by means of their pa- tent draining plough, which is adapted to be worked by the ordinary plough engine. It can be used as a mole plough, and will lay pipes in stiff clay soils at a depth of 4 ft. with perfect ease and safety.

If we examine into this proposed mode of purifying sewage, in order to produce a pure, clear, effluent water, the nature of the soil must be taken into account. Sewage must be purified in a double sense, mechanically and chemically. By the present irrigation svstem the former is effected partly by filters, extractors, and some other mechanical agency, and partly by filtration to a small depth through the soil, and the latter by the assimilating powers of the plants, with the roots of which the liquid is broaght into contact.

THE EUPHRATES VALLEY RAILWAY.

35

If, however, we irrigate the land cubically instead of superficially, a large portion of the sewage must be purified both mechan- ically and chemically by the soil alone. The question, then, is : are all soils capa- ble of acting in this double capacity? Certainly not. A peaty soil is well calcu- lated to act both as a filter and a chemical purifier, but many others will not effect the double object. It cannot be too care- fully kept in view that although water may be completely deprived of all its mechani- cally suspended impurities, and to all ap- pearance be perfectly pure and clear, it may,nevertheless, be chemically exceeding- ly impure, and totally unfit to drink. It is notorious that water slightly contaminated with sewage has not only a clear, spark- ling appearance, but, owing to its saline ingredients, is rather agreeable than other- wise to the taste. It is alike deceptive to both the eye and the palate. Accurate chemical analysis is the only test to be depended upon in determining the purity of water. Another point to be kept in mind with reference to the proposed mode of irrigating the land to the depth of sev- eral feet, is whether it would not after a certain time, become so completely satu- rated with sewage as to be incapable of any longer fulfilling the duty required of it. Although experience has hitherto furnished us with no information on this

head, yet there is no question that such would be the case. Manifestly the land would be literally a filter for the sewage. All filters, from the domestic specimens to the beds necessary for water-works, become clogged after a certain time, and must be cleaned out. The time they will last without cleansing depends altogether upon the character of the liquid they have to filter, and the case is the same with the land. Accordingly, as the sewage is more or less charged with solid ingredients, so will the land become foul and clogged in a short or a long period. But the land, when i i this condition, would have to be cleansed, which could only be accomplish- ed by abstaining from any further irriga- tion. In the interval which the soil would require to return to its normal condition — which would certainly be two or three years at least — the sewage, which is continuous in its discharge, would have to be turned on to some other land. It, therefore, is by no means certain that the total quan- tity of land required in 10 or 20 years would be so very much less than that which would be necessary under the pres- ent system of superficial irrigation. One thing is certain, that if this method was once adopted, and more land was required, it would have to be obtained at all hazards, even if houses had to be pulled down to clear the ground.

THE EUPHRATES VALLEY RAILWAY.

From '* Journal of The Society of Arts."

The report from the Select Committee on the Euphrates Valley Railway has been published, with the evidence of several distinguished Oriental travellers and emi- nent engineers, upon the route best fitted to secure a direct communication between ' this country and our Indian Empire. The Committee have, for the present, agreed to report to the House of Commons the evidence they have gathered, leaving the many important questions raised until the sittings can be resumed at the commence- ment of next session. Apart from certain minor questions of more or less relative consequence in regard to the direction which the line of railway should follow, we learn there is a divergence of opinion upon the desirability of using the Black Sea or the Mediterranean as the basis of

operations. These points were clearly explained at the outset by Sir Henry Raw- linson, the first witness called, who speaks with the authority of personal knowledge, gained by 12 years of residence and travel in Turkish Arabia. We learn from his description that several routes have been recommended which possess certain ad- vantages, and are therefore deserving of the consideration of the Committee. The first is a route which has been proposed by the Tuidrish Government, and for which the Porte gave, or offered, a concession as long ago as I860 or 1867. This was in- tended to connect Constantinople with the Persian Gulf. It was to start from Scuta- ri, opposite Constantinople ; then it pass- ed along to Izmid, Kutayich. Kara-Hissar, Kumeb, and Kf isarich to Aleppo, and then

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VAN NOSTRAND'S ENGINEERING MAGAZINE.

down the Valley of Euphrates to Bagdad and Bassorah, and from Bassorah to the head of the Persian Gulf. The distance was estimated at 1,700 miles, including a branch from Aleppo to Scanderoon. It was 800 from Constantinople to Aleppo, including the Scanderoon branch of about 120 miles ; and it was 900 miles from Aleppo to the Gulf. The second is what is generally called the "Andrews" line, or the well-known Euphrates Valley route, which is the same as the lower portion of the route described, but the essential dif- ference being that the terminus is at Scan- deroon instead of Constantinople. The distance is estimated at 850 miles, whereas it should be in reality 1,000 miles. The third route, which has been strongly re- commended to the Government by Col. Herbert, the present political agent in Arabia, would also leave the Mediterra- nean at Scanderoon, but it would subse- quently pass by Aleppo across the Eu- phrates at Bir or Orfah, which is the an- cient Edessa, and so on to Diarbekr, Nisi- bin, Moosul, and then along the Tigris to Bagdad and B ssorah. This route would be 100, or perhaps 150 miles longer than the Euphrates Valley line, as it makes a considerable detour to the north-east, but it has the advantage of passing through a number of large cities and centres of trade, and lying generally among settled and populous districts. These are the three routes which exist between the Mediterra- nean and the Persian Gulf.

There are, besides, two or three routes from the Black Sea which ought to be con- sidered. There is, in the iirst place, a route which has recently been advocated. It leaves the Black Sea at Jereboli, near Trebizond ; it crosses the mountains to the Valley of the Euphrates, at Erzingam ; it then takes a steamer and passes down the Euphrates to the point nearest to Diar- bekr ; it then crosses to Diarbekr and follows the Tigris down to the sea by steamer. This would be about 950 or 1,000 miles, partly water and partly rail- way, but the water communication would be only practicable for a few months in the year, and then only downwards. There is another route which leaves the Black Sea at or near Samsun, and follows the high road to Sivas; from Sivas it would fol- low a line by Malatieh and Diarbekr, and from Diarbekr it would follow Colonel Herbert's route to Bagdad and Bassorah.

This would be about 1,000 miles in length. There is another route also from the Black Sea, although the project has not attained any substantive form, and that is a line from Trebizond to Erzeroom, across the mountains, and from Erzeroom to Van, and then down the Betissii to the Tigris, above Moosul, and from that point along the same line as the last route. This line would cross the range of the Taurus in about its most difficult and impracticable position, and would be impossible to ef- fect, the country being cut up by a succes- sion of precipitous ravines, mountain tor- rents, and impracticable defiles. Other lines have been projected connecting Eu- rope with India, but this question involves much larger considerations than those af- fecting the mere limited question of con- nection between the Mediterranean and the Persian Gulf. There are, according to Sir Henry Rawlinson, three great lines which have been projected to connect Constantinople with India. The first would pass Constantinople along the northern or nigh road to Erzeroom; from Erzeroom, it would cross the Persian frontier to Khoi and Tabreez, and so on to Teheran, the capital of Persia ; from Teheran it would pass to Shahrood and Mushed; at Mushed it would run south-east to Herat, and so on to Kandahar, and through the Bolan pass to Shikapoor and Sukkur, where it would join the Indus Valley base. The length of this line would be nearly 3,000 miles, which is not quite so much as the line which connects Sacramento with New York, and which distance is traversed in a week. The second line also leaves Con- stantinople, and follows the central route through Asia Minor, or, as it is now generally called, " the telegraph route," being the line along which the Turk- ish wires which carry our messages to India are placed; it passes by Angora, Tusgat, Sivas, Diarbekr, and Moosul to Kifri, which is the nearest point to the Persian frontier on that line, and where our telegraph turns off to Persia. From Kifri it would cross the Persian frontier, and ascend through the "gates of Zagros" to Kermanshah, and so on by Humadan to Teheran, where it would join the route contemplated to the Indus Val- ley. The length of this line would be about 3,200 miles ; it presents engineer- ing difficulties at two points, namely, the descent of Taurus and the ascent of Za-

THE EUPHRATES VALLEY RAILWAY.

37

gros, but it has many compensating ad- vantages. There is another, or third route. From Constantinople, it would follow the same line, as far as Bassorah, as No. 1 of the limited routes; that is to say, it would pass by Kutayiieh and Kumeh to Aleppo, and along the Euphrates Valley to Bagdad and Bassorah, being absolutely the same as the line proposed by the Porte. From Bassorah it would circle round the north- ern and eastern shores of the Persian Gulf, passing by Bushire and Bunder Abbas, and would then follow the coast of Me- kran to Kurrachee. This would be some- what shorter than the upper line, about 2,900 miles, and from Bassorah, along the shores of the Persian Gulf, with the ex- ception of Bushire, there is not a town worth speaking of, and a very scanty pop- ulation— that is to say, throughout the whole distance from Bassorah to Kurra- chee.

The evidence given by Colonel Chesney bears more especially upon the advantages of the Euphrates Valley line in particular, and the nature of the country through which it passes. He observes that the route from Trebizond by the Tigris would be highly advantageous to Russia, but of little or no service to this country. The port is an open one, and therefore highly objectionable, with steep mountains be- hind it, and the Taurus beyond them. In the event of a war with Russia, and Russia having the command of the Black Sea, she would be able to shut up the terminus of the railway upon the Black Sea; whereas, if the terminus were on the Mediterra- nean, England would have the command of it, as being easily defensible, and there would be an excellent port at which to land an army. In his opinion, therefore, the line by the Euphrates from the Mediterranean is the only one desirable for the English nation to construct. The chief engineer- ing difficulties occur at the first stage from the sea, in the 15 miles traversed from Swedia, or Scanderoom, to Antioch; all the rest is easy. There would not be a single tunnel or cut to make. The popu- lation along the proposed line is very con- siderable. The Arabs would number be- tween 2,300,000 or 2,400,000 ; they come in the summer, and go away again; there- fore, there is a large population — several towns with considerable commerce. A great traffic might be established with this country from points where there is already

a large trade. The imports through Aleppo are upwards of two millions, com- ing from the line of Arabia, and the ex- ports are not far short of the same amount. The Tigris has its commerce also, but the commerce of the Tigris is not so great as that of the Euphrates. The land is favor- able to the growth of cotton, linseed, corn, and everything which is produced in India. In the early spring, clover and grass may be seen growing 9 ft. in height. It is the finest alluvial soil in the world, and is much more fertile than the land in the valley of the Tigris. There is an existing traffic passing by means of the caravans, and there has been a communication through Arabia since the time of Abraham ; it has never ceased. The caravans go through, and hardly ever meet with any difficulty from the Arabs, except a slight payment, which the sheik expects. There would be no obstruction, and labor would be readily obtainable for the construction of the works along the line. With regard to climate, the deaths from fever and ague are not numerous, and exposure would be better to bear than if exposed on the Red Sea. In comparison with the journey by the steamer on the Red Sea, the railway would be easier, the current of air would be more refreshing ; in the case of the former, the steamers are often forced to turn round so as to get air into the ship, to save the passengers from the intense heat. Eor the conveyance of the light, valuable goods, mails, passengers, troops, and treasure, the Euphrates route would be the best, and both lines would assist each other ; there are people and commerce enough to occupy both. The distance would be, from London to Brin- disi, 1,504 miles; from Brindisi to Selucia, or Scanderoon, 900 miles. The line of the Euphrates, along the river, as proposed for the railway, is 850 miles, that is from the sea to Bassorah; then, from Bassorah to Bomba}1", the distance is 1,690 miles. The total distance from London to Bom- bay is 4,944 miles. The route, via Brindisi, Suez, and Aden, the distance is 5,472 miles, from London to Bombay, and from Lon- don to Kurrachee it is 5,247 miles. The difference in favor of the Euphrates line is, from London to Bombay, 528 miles, and from London to Kurrachee, 803.

With respect to the arrangements that it would be necessary to enter into with the Turkish Government, and the means

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VAN NOSTRAND'S ENGINEERING MAGAZINE.

by which the capital to complete the under- taking could be raised, we learn the full particulars in the evidence given by Sir George S. Jenkinson, Bart., a member of the Committee. From conversations and written communications with the Turkish Minister, his Excellency, it appears, on every occasion expressed himself person- ally most anxious on the subject, and that the completion of the project would be es- pecially favored by the Sultan. The result of these interchanges of opinion was re- duced to a written document.

The Turkish Government consents to the construction of the railway on its own account, from Alexandretta to Aleppo, and from Aleppo to Bagdad and Bassora, at the head of the Persian Gulf, under the direction and working control of a mixed committee, to be jointly appointed by the the English and Turkish Governments,and upon the following conditions : — 1. The funds to be raised b}r means of an Otto- man loan, the interest of which to be counter-guaranteed by England, at the rate of 4 per cent, per annum, and one per cent, for sinking fund. 2. The proceeds of such loan, when raised, to be deposited in the Bank of England, in the names of the mixed committee, and to be applied by them exclusively for the construction of the railway, and the provision of the necessary rolling-stock, and for no other purpose. 3. All the land necessary for the railway, and for all the works in con- nection therewith, to be provided for by the Turkish Government. 4. In order to secure, with regularity and certainty, the

payment of the interest upon the loan, the following stipulations to be agreed upon and enforced : — 1st. The net income pro- ceeds of the working of the railway when made, wholly or any part of it, to be paid into the Bank of England, and applied exclusively to the payment of the interest of the sinking fund. 2d. The customs duties and port charges of the ports of Alexandretta and Bassorah, as well as certain revenues and other resources of the province through which the railway may pass, to be assigned by the Turkish Government to the mixed committee, as a security for the payment of the interest of the loan and of the sinking fund. 5. The Turkish Government to guarantee to Eng- land the privilege of the conveyance of troops at all times by the railway to and from this country and any of Her Majes- ty's Eastern possessions, and at a rate not exceeding that which will be paid for a conveyance of troops belonging to the Ottoman Empire, and upon such other conditions and regulations as shall be set- tled and agreed upon by a convention be- tween the English Government and the Sublime Porte. 6 . The transport, free of any charge, at all times, by the railway, of all English mails to and from this country, and any of Her Majesty's Eastern provinces. 7. Until the extinction of the loan, by the repayment of the principal and interest, the English Government and the bond-holders, as represented by the committee, to have an absolute mortgage upon the railway, and land, and works.

GASES FROM THE BESSEMER CONVERTER *

By MR. G. J. SNELUS, A. R. S. M.

This investigation was undertaken in the hope of solving some of the difficulties connected with the spectroscopic observa- tion of the Bessemer flame, and also as likely to afford a further insight into the nature of the process going on in the con- verter.

The gas was collected for analysis by means of an iron gas pipe, having a swan- necked trumpet mouthpiece of fire-clay, which was dipped into the mouth of the

* Abstract of a paper read before the Iron and Steel Tnsti- 'ute, on the Composition of the Gases evolved from the Bes- semer Converter during theB.ow.

vessel after it had been turned up. The gas from its pressure in the converter, rushed through the pipe with some velocity, and after the whole of the air had been swept out, glass tubes were attached, and when filled with gas, at particular periods of the blow, were hermetically sealed up with the blow-pipe before removal.

The gas was analyzed in some cases by two different methods, and the duplicate results were found to agree.

The following tabular statement shows the composition of the gas at different periods of a blow lasting 18 minutes:

GASES FROM THE BESSEMER CONVERTER.

39

	No. 1 Taken 2. from start.	No. 2 4.	No. 3 6.	No. 4 10.	No. 5 12.	No. 6
	14.
	10.71 None. .92 88.37	8.57 3.95 "88 86.58	8.2 4 52 Absent. 2 00 85.28	3.58 19.59 Absent. 2.00 74.83	2.3 29.3 None. 2.16 66 24 None.	1.34
	31.11
	None.
	2.00
Hydrocarbons	65.55
	100.00	100.00	100.00	100.00	100.00	100.00

On dissecting these results we find that the oxygen corresponding to the nitrogen in No. 1 is sufficient to oxidize not only the 4.43 parts by weight of carbon that are contained in the gas, but also 11.91 parts of silicon, and as these two bodies are practically the only ones being burnt from English Bessemer iron at this period of the blow, we may take it that these are actually the proportions in which carbon and silicon are now being got rid of from the metal. And this is exactly what anal- yses of the metal at this stage show, for it was found in one instance that metal containing 3.57 parts carbon and 2.26 sil- icon at the commencement, lost .53 parts of carbon against 1.305 parts of silicon in the first few minutes. Analyses of the gas from another blow about the same time, made by W. Thorp, F. C. S., of the Rivers' Commission Laboratory, show practically the same results. Sample 3 shows that 5.27 parts of carbon are being burnt along with 11.74 parts silicon. Sample 4 was taken after the commence- ment of the " boil " when the complete carbon specimen had become permanent. It shows quite a different result from the previous analysis, the large percentage of carbonic oxide now present explaining why the flame has become so much more luminous. We now find that 9.6 parts of carbon are being oxidized along with 6.25 parts of silicon. Sample 5 was tested specially for hydro-carbons ; but none were found. Sample 6 shows that 13.45 parts of carbon are being burnt at this period and only .46 parts of silicon, which corresponds with analysis of the metal, these proving that the last traces of sili- con go off very slowly.

The author considers that the reason why carbonic acid is formed during the first part of the blow, and carbonic oxide at a later stage is to be found in the in-

crease of temperature during the blow. This agrees with experiments of Mr. Bell, who proved that at a low temperature carbonic acid was more stable than car- bonic oxide in contact with iron, but that at a high temperature the reverse was the case. It also agrees with general obser- vations. As a general result the compar- ison of the gas analyses with spectro- scopic observations, shows that the rea- son why we get a continuous spectrum at the commencement of the blow is that we have then only white hot solid matter to look at, there being no actual flame, and the temperature being too low to give the specimen of carbonic acid, while later in the blow we have an abundance of car- bonic oxide burning at the mouth of the vessel, which is also at a very high tem- perature, and, therefore, we get a carbon spectrum which is distinct from other carbon spectra yet seen, because we have not yet been able to examine the spec- trum of carbonic oxide at the particular temperature of the Bessemer flame. Mr. Snelus believes that Deville's theory of the increased luminosity of flames under great pressure being due solely to the in- crease of temperature, is applicable to the great luminosity of the Bessemer flame compared with that of carbonic oxide burning at a low temperature. On com- paring the gas from the Bessemer con- verter during the latter part of the blow with blast furnace gas, and with analyses of gas from Siemens' producers, given by the wi'iter, it is seen that the former is as valuable a fuel as any of them, and as works using 1,000 tons of pig per week is send- ing this gas to waste at the rate of an equivalent of 25 tons of coke per week, its economical application becomes a point of great importance.

The writer believes this could be ac- complished in a simple manner.

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VAN NOSTRAND'S ENGINEERING MAGAZINE.

THE NORTH SEA CANAL *

"A visit to the Suez Canal in my canoe (•which was related in the "Times" a few years ago) enabled me to compare the North Sea Canal with that larger, more mundane, but not more remarkable exam- ple of human industry and patience, cut- ting the land in two to abridge the seas, levelling "whole mountains of sand, battling with deep tides and hidden springs, stormy waves, and thousands of dubious or im- patient shareholders — by far the most difficult obstacles for the venturous capi- talist and the clever engineer.

"I have already explained that the North Holland Canal, which was cut to save a roundabout from Amsterdam by the Zuyder Zee, is more than 50 miles long, and enables large ships to enter Holland at its extreme northern end. But this canal is too long, too narrow, too tortu- ous, and too shallow for the increasing length and depth of our largest merchant vessels. To save time, then, and much trouble and transhipment, the new canal opens to the west instead of to the north. It is 1 5 miles in length instead of 52. Its depth is 26 ft. available instead of 16 ft., and no bends or sudden turns obstruct the passage anywhere. Six years ago this work was begun by the well-known Eng- lish contractor, Mr. Lee. With Mr. Hawkshaw and Mr. Dircks to plan, and Mr. Freeman to execute, and a wealthy company to pay for it, all good folks ought to expect success.

"At present the work is precisely in that condition most interesting to inspect, being just beyond the state in which any doubt can remain as to ultimate success. Very likely this success will sap the other canal, and reduce Nieuwe Diep to a marine depot ; perhaps it will also draw the golden tide from Rotterdam, but perhaps, too, the merchants there will shift their quarters to the better entrepot of Amster- dam, and yet perhaps, indeed, when all is done a certain German Prince will stretch out his iron hand and ask for the new road, and very graciously thank those who made it for him.

" First of all, locks are being placed on the east, to enclose an artificial lake about 12 miles long, at one end of which rests

* From Mr. Mc Gregob's letter, "London Times," through "Engineering." 1

Amsterdam, and a deep channel is dredg- ed along this lake, with two banks gradu- ally rising into solid tow-paths. Minor canals, in all about 12 miles long, are left on either side to communicate with the little towns now on the shares of the Y, but all this intermediate area of water will be pumped out, and so nearly 12,000 acres will thus be reclaimed. No one can say how much this new territory will sell for, but an acre I asked about at random was valued at .£100. The average may be | of this sum.

"The dredging is far better done than it was on the Suez Canal. The machinery has been steadily improved and simplified, and the latest and best appliance was only completed a few days ago. This consists of a tube resting near the ooze at the bottom, and containing a shaft with a centrifugal pump, which draws up the sand and water bodily — about half of each in the mixture — and forces it along wood- en pipes floated on the surface of the wat- er, and flexibly jointed by leather hides. The slush is thus poured through a con- duit about 300 ft. long and 1 ft. broad, which resembles a huge black snake coiled and asleep on the water, and with its tail turned over the bank at the side. Through this tail, even when it is raised 8 ft. above the level, a copious fluid rushes, black as ink, but fertile for the next 100 genera- tions of cheese-making Hollanders. So simple is this plan that already it is being applied to the great banks of the Danube, and I saw boxes full of the hide joints be- ing sent to the Sulina mouth. Not many, but still some, curiosities have been found in the ground dug up or dredged for the canal. An enormous mammoth's skull and huge bones of the same fill one end of Mr. Freeman's office, and these ought to be in the British Museum, and could, I believe, be readily forwarded if properly applied for. One human skull has been dredged out 9 ft. below low-water mark, and I am enabled to bring it home. The size is large, the frontal part very small, the forehead being scarcely more than an inch in height. One or two pottery pieces have also been found, and, of course, plen- ty of shells. As no gravel has appeared in the matter dredged from below, it seems plain that the idea is erroneous which has long suggested that an ancient mouth of

SOFT IRON AND STEEL CASTINGS.

41

the Rhine once led through Holland at this spot.

"The banks thus formed are gradually raised above the surface to the average of 3 ft., and then a layer of stiff clay is placed over the sand. On this is spread a sort of matting of loose reeds, which grow pro- fusely in every lagoon. Long twigs of the willow-like tree, named ' rys,' are then laid down, and stakes about 4 ft. long are driven through them in rows, while a regular-twisted wattling of ' rys,' is secure- ly worked into these, and the whole as- sumes a most business-like aspect, utterly different from the loose, unprotected sand- banks of the Suez Canal, which latter the water, the wind, and their own weight all conspire to ruin. Better than all the rest, a plant called 'helm,' which grows natur- ally on the sand-hills, is being planted like cabbage rows upon the new-formed banks, and this rapidly takes root, and binds all together.

" This plan is to be tried on the Suez Canal, but probably the climate and the larger proportion of salt water in the Egyptian sand may prevent the 'helm' from growing there. At the end of the lake we reach the 4 miles of solid sand and eleva- ted ground which had to be cut through before the western shore of Holland is attained. The deepest cutting is not more than 100 ft., and is a mere matter of dig- ging and carrying away. At length we come to the locks close to the sea. These are of enormous size, 500 ft. long and 60

ft. broad, with a depth over the sill of 30 ft. The stone-work facing of these is beautifully fitted, and the 25,000,000 of Dutch bricks here laid are a model of bricklaying. The width of the canal from centre to centre of the towing-path is about 500 ft., but at the edge of the main channel only 200 ft., and 80 ft. at the bot- tom; but this gives ample room for the largest vessels to pass each other. Now we are in the thick of the 'dunes' or sand- hills, Holland's western wall. They are not bare, but rather jungly in their look, and hares and rabbits, and curlew and spoonbills are plentifully found by the sportsmen on these wilds. Climbing this barrier we can look down on the two gi- gantic pier arms that stretch forth boldly into the stormy sea, and which keep stead- ily lengthening every week, and gradually bending in their ends