whether the steel for the fire-boxes could be crucible steel. Mr. Fox believed that almost, if not all, the steel used in America up to within a short time was crucible, but that Bessemer steel was now being largely worked. The steel used for fire-boxes was certainly not the same as that adopted for boilers; but the difference was a secret not easily obtainable. The cold-water and bending test spoken of was certainly applied to fire-box steel inch thick. With regard to cast-iron wheels, there could be no comparison between the qualities of English and American cast iron, and a good deal of misapprehension had arisen from that fact.

The reason for cast-iron wheels having been so successful in America was to be found, partly in the quality of the iron, and partly in the manufacture. Mr. Gunn, Assoc. Inst. C.E., had laid on the table some specimens of American pig iron, the analysis of which showed its high quality. One example was a

The following analyses of American pig iron have been kindly communicated by Mr. Gunn, Assoc. Inst. C.E. :—

Eagle, Longswamp, Black Lake, are all cold-blast charcoal irons of extraordinary strength, made from superior ores, which ores are first roasted and then smelted. A stalwart man using a heavy sledge-hammer will often grow weary when trying to break a pig of either of these irons. Two strong men have been seen to take turns in hammering, and finally to give up in despair. For locomotive boiler plates, chilled rolls, and any purpose where great strength is needed, these irons are very valuable.

Salisbury is known widely as a cold-blast charcoal iron of high character. Iron can be furnished which has a tensile strength in the pig of from 28,000 to 35,000 lbs. to the square inch.

piece of a car wheel which had run 70,000 miles, and which, even then, showed a tensile strength of 33,000 lbs. per square inch. Mr. Starbuck, of Birkenhead, who had a large experience in tramway cars, said he could never get English cast iron to stand, and that he therefore used American wheels. Two or three processes of annealing were adopted. In one of these, introduced by Giesse in 1859, the wheels were removed, whilst hot, from the mould, and so piled up in a cylindrical chamber, that the 'hubs' or naves formed a chimney, through which a blast of air, which could be regulated by dampers, was passed, thus gradually cooling the wheels from the centre and preventing the naves from shrinking away from the rims, as might otherwise be the case. In another process, adopted by Mowry in 1861, the wheels were built up in a pit having double walls, with layers of charcoal between them, and were exposed to moderate but protracted heat, and then allowed to cool very gradually. In both these processes care was needed to prevent the heat being such as to draw the chill, which had been imparted in the mould, to the treads and flanges, and which penetrated to a depth of from to inch. To avoid this difficulty a modification, by Moore in 1865, removed the wheels from the moulds while hot and placed them above one another in a chamber, with rings between the tires so as to shut off the chilled portion of the tire from the inner part of the wheel; the naves were then immersed in charcoal, and the tires in sand. The charcoal slowly burned, gradually annealing the bosses of the wheels, while the sand prevented the chill from being injured. In the case of cast-iron driving wheels, dry steam was passed through them while they were lying in the mould itself. He would direct attention to some experiments recorded in the "Engineer" for November 6th, 1874, showing the remarkable strength of American cast-iron wheels. One wheel 2 feet 7 inches in diameter, when subjected to a pressure applied to the rim in direct line with the nave, with a bearing upon the rim of 5 inches, required 110 tons to break it. Another was first forced by a pressure of 134 tons on to an axle larger than the hole in the nave, was then taken off, and bore a pressure of 178 tons, applied to the rim, as in the former case, without fracture. One reason for using cast-iron wheels in one place and steel tires in another was that the Americans did not generally elevate the outer rail on curves, so that the leading wheel of a bogie truck had a great deal to do; besides, the work of guiding was thrown entirely upon the bogie truck. The consequence was that steel tires being soft, wore thin, and became dangerous, whilst in cast-iron wheels the chill was so hard

that they could not be turned; by which also the expense of turning-up was saved. A cast-iron wheel was also safer in cold weather than a wrought-iron tire, being homogeneous and less liable to snap. On the St. Petersburg and Moscow railway, and on Canadian lines, cast-iron wheels had stood a temperature 40° below zero, in which wrought iron or steel would be liable to break. Such wheels were very durable, having a life of 100,000 miles, no authority putting it less than 75,000 miles. With driving

wheels the case was different. The diameter was large; the surface of the tread must be soft and true; and when it became untrue, it must be capable of being turned up again. At the date of Mr. Colburn's Paper chilled tires were in use, but they were now generally abandoned, except for shunting engines, where the driving wheel had to do some of the guiding. In that case, the tire was fastened by a slight coning of the rim to the extent of inch in 5 inches and by rim bolts.

The extra width of cuttings was given because of the amount of snow that collected at the bottom of the slopes. Shimming consisted in raising the rail by strips of wood on the top of the sleeper, when the ground was frozen so hard that it could not be moved. The first frost upset the track; then a thaw came, and afterwards a frost again; and the road got into such a lamentable condition, that, but for shimming, nothing could be done with it during the winter. If the shim was thick it was placed upon the sleeper, and two spikes were driven through to secure it to the sleeper, and separate spikes to secure the rail to the shim itself. Shims were sometimes employed to take 'slacks' out of the road when it was not frozen. With reference to the weight of rails, allusion had been made to difficulties which had arisen on the Ilfracombe railway. He considered the fault lay, not with the rail, but with the engine. Had a bogie truck been used, the rigid wheel base been reduced, and the weights adjusted, the rail would not have been damaged. He had adopted much lighter rails, weighing only 40 lbs. to the yard, in Canada, where the frosts were severe, and in Australia, and elsewhere, in connection with sharp curves and steep gradients, and they answered well even for heavy traffic, where the speeds were slow, and the rolling loads did not exceed 3 tons per wheel. Dr. Pole had asked a question as to fang-bolts. Formerly the general practice in Canada was to have an insistent joint for fastening the rails; but he considered that insufficient, and therefore arranged for a fang-bolt with an extra length of thread, so that shims could be used to some extent; but, although loosely fitted, the fang-nut soon rusted

up hard and fast, and it had to be abandoned. The chief engineer of the Toronto, Grey, and Bruce railway, Mr. Wragge, M. Inst. C.E., had now reverted to suspended joints, and only dogspikes were used. In this country wood screws were not only expensive, but liable to be converted, by being driven instead of screwed into the sleeper, into inferior spikes. If screws were to be used at all, it would be well to adopt the American threethreaded screw, which was intended to be driven, turning round in penetrating the timber. Such screws were largely used in the United States for packing cases. Some surprise had been expressed at the short time occupied in the change of gauge mentioned in the Paper. His brother, Mr. Francis Fox, M. Inst. C.E., was in America when it occurred, and the statement was taken from official records. A similar operation was carried out on the Grand Trunk railway in October last. At ten o'clock in the morning of the 26th a length of 552 miles, or including sidings, 600 miles of railway was cleared of traffic; and by one o'clock on the following morning the gauge was completely changed. Two thousand men were employed. In Captain Tyler's report on the Erie railway some interesting statistics were given on this subject. In conclusion, he hoped this discussion might aid in awakening increased interest in the public works of the United States, and that English engineers would be led to visit in greater numbers a country where they would find their professional brethren not only most courteous, but able and enterprising in the highest degree.

1 Vide "Report on the Erie Railway, and its Connections," p. 27. Folio. London, 1874.

[December

December 1, 1874.

THOS. E. HARRISON, President,

in the Chair.

And

December 8, 1874.

JOHN FREDERIC BATEMAN, Vice-President,

in the Chair.

The discussion upon the Paper, No. 1,332, on "The Pennsylvania Railroad; with remarks on American Railway Construction and Management," by Messrs. Charles Douglas Fox and Francis Fox, occupied the whole of these evenings.

The following candidates were balloted for and duly elected on the 1st of December:-ROBERT DUNDAS, ROBERT GORDON, FRANCIS BAKER HANNA, ALFRED REID CLANNY HARRISON, PETER ALEXANDER PETERSON, WILLIAM HENRY THOMAS, and JOHN BROWN YOUNG, as Members; HENRY CHARLES BAGGALLAY, Stud. Inst. C.E., DONALD BARLOW BAIN, CHARLES SPRUYT DE BAY, DONALD STUART BAYNES, Lieut. JAMES BREBNER, FRANCIS EUSTACE BURKE, Stud. Inst. C.E., JOHN CLARK, GEORGE FITZ-ROY COLE, ALFRED DAVIS, EDWArd BauDOUIN ELLICE-CLARK, GEORGE ESTALL, GEORGE LANCELOT EYLES, CHARLES RICHARD FENWICK, Stud. Inst. C.E., GEORGE FINDLAY, WILLIAM GILCHRIST GILCHRIST, Stud. Inst. C.E., HARRY DANIEL GOOD, JOHN DUNCAN GRANT, WILLIAM CECIL GUNN, EDMUND LEGH HARRIS, HENRY BEECROFT HARVEY, WILLIAM HARVEY, Lieut. HENRY SIDNEY FREEMAN HAYNES, R.E., WILLIAM MARSHALL HEWAT, JOHN HEWSON, WILLIAM EDWARD HORN, Stud. Inst. C.E., FLETCHER JAMES IVENS, Stud. Inst. C.E., GEORGE JOHN MANDERS, WILLIAM HOLT MARTIN, Kenneth WILLIAM ALISTER GRANT MCALPIN, DAVID EDWARD MCDONALD, VITALE DOMENICO DE MICHELE, Lieut. JOHN FRANCIS JAMES MILLER, B.S.C., MUNCHERJEE CAWASJEE MUrzban, WILLIAM ENSOR PARRY, THOMAS PEACOCK, ALFRED PHILLIPS, ALFRED COVENEY PRIESTLEY, JOHN RAWLINS, FREDERICK EWART ROBERTSON, FREDERICK SMITH, HARRISON VEEVERS, and SAMUEL JOHN WILDE, as Associates.