CHAPTER XXXVIII.

ON THE COMPARATIVE MERITS OF IRON AND STEEL RAILS.

An article in the "London Quarterly Review," for July, 1866, says:

"The first wrought-iron rails laid down were only twenty-five pounds to the yard; but they were soon found too light for the loads they had to carry. When George Stephenson was examined by Mr. (afterwards Baron) Alderson, before the Committee on the Liverpool and Manchester Railway Bill, he was taken to task about the weakness of the Hetton Road, and the danger of travelling by railway, on the assumption of trains being run at the dangerous, but then hypothetical, speed of twelve miles an hour. The witness was asked 'Do not wrought-iron rails bend-take Hetton Colliery for instance ?'-'They are wrought-iron, but they are weak rails.' 'Do you not know that those bend? Perhaps they may bend, not being made sufficiently strong.' 'And if they are made sufficiently strong, that will involve an additional expense ?'—' It will.' Then if you were to make them of adamant, that would be very expensive?''It does not require a very great expense to make them strong enough for heavier work.'

"That there might be no deficiency of strength in

the fish-bellied rails first laid down upon the Liverpool and Manchester line, they were made of the unusual weight of thirty-five pounds to the yard. But the extraordinary speed of the locomotive had not yet been discovered, and there is no doubt that the performances of the 'Rocket' surpassed the expectations of even George Stephenson himself. Although the engine weighed only four and a half tons, it proved too heavy -when running at high speeds-for the malleable rails; and as the traffic grew, and heavier engines were introduced on the line, the weight of the rails was increased from time to time, but not in like proportion to the weight of the locomotives. For while the malleable rails have been increased from twenty-eight pounds to seventy-five and even eighty-six pounds to the yard, the locomotive has been increased from four and a half tons, as in the 'Rocket,' to thirty and thirtyfive tons, the weight of first-class express engines. The disproportion between the weight and force of the engine and the resistance of the rail has been constantly increasing; until the point has at length been reached at which no additional weight in the rails will enable them to resist the crushing load of the modern locomotive. As in the case of the battle between guns and iron plates, the weight of both has been increased, until at length, unless a new material-the 'adamant' imagined by Mr. Alderson-be employed, it is clear that as regards the locomotive and the iron road the latter will be vanquished in the contest. The defect is in the material, to which a crushing power is applied which ordinary iron is positively incapable of resisting. The points of contact of the wheels of a thirty ton loco

motive with the rail are very minute, and upon these points, the whole weight of the engine presses. The effect is to squeeze and crush the iron and roll it off in laminæ, as any one may observe who examines a rail laid down on a line of heavy traffic that has borne a fair amount of work under the heavier class of engine.*. On some of the metropolitan lines iron rails, especially if placed on sharp curves, will scarcely last a year. Hence the railroad has become even less 'permanent' now, with its rail of iron, than it was with its original rail of wood a hundred years ago. It has thus become absolutely necessary to introduce a new material, and that material is to be found in Steel.

"The greatly superior resistance which steel offers to crushing as compared with iron, may be learnt from the experiments made by Mr. William Fairbairn, with the object of ascertaining their respective strengths in this respect. A piece of cast-iron, both ends flat, was crushed by a pressure to which it was subjected of fiftyfive tons to the square inch; and a piece of malleable iron of the same shape was flattened by a pressure of seventy-three tons to the square inch; while a piece of steel of the same shape resisted a pressure of one hundred and twenty tons per square inch without being

"The friction between the driving wheels and the rails, when the engine is thundering along at high speed, is also very great, and the iron is ground off in minute particles, and thrown into the air. Dr. Angus Smith, when once travelling by railway, took the pains to collect some of the particles which floated about him in the carriage and seemed to shine with metallic lustre. On examination they were found to be in reality minute rolled plates of iron, which seemed to have been heavily pressed and torn up from the surface of the rails."

either crushed or flattened.* The result of certain American experiments, quoted by Mr. Mallett, was to a like effect. The mean resistance of cast steel to com. pression was found to be two hundred and ninety-five thousand pounds, of cast iron, one hundred and twentyfive thousand pounds, and of wrought iron eighty-three thousand five hundred pounds; while the tensile strength was forty tons for mild cast steel, twenty to twenty-five tons for wrought iron, and ten to twelve tons for cast iron. Thus in cast steel we find material not only capable of resisting a far greater compres sive force than any known metal can do, but also one whose tensile strength is nearly double that of wrought and more than three times that of cast iron.

"The comparatively perishable nature of wrought iron when subjected to the crushing load of the modern express locomotive, has necessarily led to a large increase in the annual cost for maintenance and renewal of railways. Thus, while the percentage of locomotive expenses on gross receipts has somewhat decreased on the Great Northern line during the last fourteen years, the cost of maintenance of way has increased during the same period more than two hundred per cent. In an excellent practical paper recently read by Mr. R. Price Williamst before the Institute of Civil Engineers, some striking facts were adduced in illustration of this rapid increase in the

* "Treatise on Iron Shipbuilding." By Wm. Fairbairn, C. E. 1865. p. 48.

On the maintenance and renewal of permanent way. Read by R. Price Williams, M.I.C.E., before the Institute of Civil Engi neers, March 12, 1866.

tear and wear of permanent way of late years. It was shown that during a period of thirteen years, most of the Great Northern up-line between Potter's Bar and Hornsey, where there are heavy descending gradients, has been renewed not less than three times, giving an average of only three and a half years as the 'life of a rail' under heavy coal and passenger traffic worked at high speeds. That it is 'the pace that kills' as well as the weight, is obvious from another fact stated by Mr. Williams with respect to the Lancashire and Yorkshire line, where an equal number of trains of about the same tonnage as in the case of the Great Northern line, were worked at low speeds over a portion of railway between Bury and Accrington, but there the rails. lasted as long as seven and a quarter years.

"The heavy cost of maintenance and renewals on the London and Northwestern Railway has for some time been a marked feature in the accounts of that Company. As the renewal of the road is properly chargeable against revenue, any large increase of expense on this account necessarily tells upon dividend; and hence, to relieve revenue against exceptionally heavy charges for renewals, the expedient of a suspense fund has been adopted by some of the larger companies. But, in 1857, the suspense renewal fund of the London and Northwestern Company was found to be so heavily in debt, that the only practical mode that could be devised for dealing with it was to write it off direct to capital to the amount of two hundred and fifty-six thousand five hundred and eighty-eight pounds; and since that date fifty-six thousand pounds have been charged to capital for renewals in like