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88 THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. [March 1, 1SC8. the head, No. 2 iron for the foot or flange, and old iron rails for the remainder of the pile. In the third division of the Paper, as to the best and most eco nomical material to be employed for rails, the following calculations were made :—Assuming that, under a very heavy traffic, common iron rails would last five years, steel-top rails fifteen years, and solid steel rails thirty years, and that iron rails would cost £7 per ton, steel- top rails £10 per ton, and solid steel rails £15 per ton, and that the old steel-top and iron rails were valued at £4 per ton, and the old solid steel rails at £8 per ton, then, with a rail section of 84 lbs. per yard, 250 tons of rails would be required for one English mile of double line, and the cost of laying the rails might be estimated at £1 per ton. On these assumptions the Author has calculated the following ANNUITY TABLE, No. 1. Interest calculated in each case at 5 per cent. ANNUITY WOULD BE FOR PRICES. Credit for Iron Rails ... Steel Top do. Solid Steel do. Iron Rails. Steel Top Rails. £ 587 417 332 280 179 134 130 £ 395 307 247 218 163 14S 140 Solid Steel Rls. £ 325 27 245 230 205 201 200 When Iron Rails last. Old Iron Rails ... „ Steel Top do. „ Solid Steel do. Per Ton. . £4 4 . 8 Per Ton. . £7 . 10 . 15 Years. 2 3 4 5 10 15 20 This table might be thus explained, as to iron rails lasting five years :— £ s. d. 250 tons, at £7 per ton 1,750 0 0 Cost of laying down 250 0 0 £2,000 0 0 Which sum, at the end of five years, at 5 per cent, compound interest, became . . 2,552 0 0 The difference between this sum (viz., £2,552) and the value of the old rails (250 tons, at £4 per ton = £1,000) was .... 1,552 0 0 The annuity required to recoup this latter sum in five years was £280 0 0 It might be objected that the prices quoted for solid steel rails were too high. Rails of this kind had been sold in some places as low as £12 per ton, but for the best quality the present price was £15 per ton, and it was only from these that the experience had been gained, as to their enduring six times as long as iron rails. However, Table No. 2 had been calculated for the different kinds and periods at the following prices, viz., iron rails at £6, steel-top rails at £9, and solid steel rails at £12 per ton, crediting the old iron and steel-top rails at £3 per ton, and the old solid steel rails at £5 per ton. ANNUITY TABLE, No. 2. ANNUITY WOULD BE FOR PRICES. Per Ton. Iron Rails £6 Steel Top do 9 Solid Steel do 12 Credit for Per Ton. Old Iron Rails £3 „ Steel Top do. ... 3 „ Solid Steel do. ... 5 When Iron Rails last. Iron Rails. Steel Top Rails. Solid Steel Rails. Years. £ £ £ 2 574 382 288 3 404 283 233 4 319 234 230 5 268 206 174 10 166 149 168 15 133 136 163 20 117 126 150 This table showed that in all cases solid steel rails were the cheapest. The amount of traffic must, therefore, decide which material it was the most economical to use for the maintenance of the permanent way. For all railways where ordinary iron rails were worn out in five years, or in a shorter time, solid steel rails were the most economical, at the prices quoted in Table 1. Where ordinary iron rails lasted over five and up to ten years, steel top rails would be the cheapest; iron rails in these cases being clearly proved to be the most expensive, although the cheapest where they lasted from fifteen to twenty years. The preceding tables referred to rails of the Vignoles section. Table No. 3 had been made up for the ordinary double-headed rail, for 1 English mile of double line, according to the prices stated, the con siderations being the same as in Table No. 2, excepting that the chairs had been taken into account. Allowance had been made for 140 tons of new chairs per mile at £5 per ton, credit being given for the value of the old chairs at £2 10s. per ton. It might be observed, that steel headed rails were here estimated to last four times, and solid steel rails eight times, as long as ordinary iron rails—that was making allow ance for the use of both faces. ANNUITY TABLE, No. 3. PRICES. Per Ton. Iron Rails £6 Steel Top do 9 Solid Steel do. ... ... 12 Chairs (140 tons pr.mile) 5 When Iron Rails last. ANNUITY WOULD BE FOR Iron Rails. Steel Top Rails. Solid Steel Rails. Years. 2 3 4 5 10 15 20 £ 780 551 436 366 229 183 163 £ 379 291 244 223 177 166 162 £ 296 249 8 217 199 Credit for Per Ton. Old Iron Rails ... £3 „ Steel Top do. ... 3 ,, Solid Steel do... 5 „ Chairs 2/10 Table No. 3 indicated that the iron rails were in no instance the cheapest: but, on the contrary, that when iron rails lasted only five years, solid steel rails had the advantage, and where iron rails had a longer duration, then that steel-headed rails were the most eco nomical. Another fact had still to be taken into consideration, the safety of the three different materials, in regard to high speeds, severe climate, &c. A report recently published by Professor Styffe, the Director of the Government School of Mines at Stockholm, showed the extent to which the tenacity and elongation of various materials were influenced by the amount of carbon they contained. From the tables which ac companied the Report, it appeared, that the hardest material had the greatest absolute strength, both before and after permanent set had taken place, but it had the least ductility ; on the other hand, a softer material had the greatest tenacity or elongation, the Bessemer material giving the same results as that prepared from the same pig iron by puddling, refining, or the cast-steel process. In a diagram illustrating these results, the per centage of carbon and of phosphorus was stated in nearly all cases. The limit for the amount of carbon seemed to be for the Bessemer material 1'2 to 1*5 per cent. With a larger amount the absolute strength, as well as the tenacity, had been found to de crease. When the amount of carbon did not exceed 0'4 per cent., and the material was not worked at too low a heat, the elongation seemed to be 16 per cent., or the same as for puddled iron from the same pig iron; and, as such Bessemer material was not only much stronger, but also more solid or homogeneous than the puddled material, it deserved a decided preference for all railway purposes. The few cases of the failure of rails by breaking might be accounted for as the result of too hard a material, not perfectly manufactured, having been made at an early period of the introduction of the process. The experience which had now been gained should certainly prevent any recurrence of this. It must, however, be observed that the raw material used in both cases was charcoal pig iron, of a superior quality compared with that used in England for making Bessemer rails, which might be seen from analyses made by two eminent chemists of both countries, which were given. These analyses showed that the great difference between the two was the excess of silicon in the English, and of manganese in the Swedish pig iron ; thus explaining why the one gave a better product than the other, although worked entirely without the addition of spiegel-eisen. If there were only 0 ’6 per cent, of carbon in the solid steel, and 0 *3 per cent, in the steel for the steel head, the safety ought to be the same for all the three kinds, and this would not influence the former calculations as to which ■was the best and most economical materials for rails. Having watched the development of the Bessemer process in Eng land, as w’ell as on the Continent, it seemed to the Author, that by that process a good and pure raw material had the same advantage, over an inferior one as in all other processes, and that a superior pro duct could not be obtained from an inferior raw material by that pro cess any more than by any other. In having mentioned Swedish material, as an example, it must not be supposed that it was wished to advocate the use of Swedish iron in this country, but simply to draw attention to the better material; as equally good charcoal iron could be supplied from Canada and India—both English colonies. It might also be remarked, that the Author’s endeavour had been to arrive at the truth irrespective of prejudice, and that he had no wish to be deemed an advocate for one kind of rail more than for any other.
