3!4 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[September, 



creasing ihe depth, if possible, this is the point to be attended to. It thus 

 appears that a Height of 36 lb. per yard is required to sustain the engine, 

 and all beyond ivill belong to the mode of attaching the rail to the support 

 below. 



In treating of the wear and tear of rails. Mr. Nicholas \Voo'l has given 

 some curious and interesting results of experience : but the weight of the 

 locomotive engines used is stated to have been only 10 tons, and of this the 

 weight on the driving-wheels would probably not e.'iceed si.'; or seven tons. 

 The result of a v.iriety of experiments on the malleable iron rails of the 

 Stockton and Darlington Railway gave one-tenth of a pound per yard as 

 the absolute amount of fair aiirasion ; some statements, liowi'ver, made it 

 much highi-r. being one-sixth of a pound. On the KiiiingAorih Colliery it 

 was one-eighih of a pound. On the Liverpool and Manchester Railway, some 

 years ago, three rails were talien up. carefully cleaned and weighed, relaid. 

 and taken up again at the end of one, and again at the end of two years • 

 the wear v^■as found constant, and about one-tenth of a pound per yard per 

 annum. If we were to take this to be the true wear, and suppose it to arise 

 vholly on the upper surface of the rail, the result would be but the 84ih 

 part of an inch m depth, and it might be supposed to take 100 years to wear 

 away a rail from mere abrasion. But later experience shows that the increased 

 weight of engines acts very destructively on lails whose upper webs are not 

 sufficiently strong, and of the best manufacture. We may take 10 tons as 

 the present average weight on the dviving-i\ heels of a locomotive engine; 

 and, if this is to be eflectually provided for. the button, or tearing part of 

 the rail, must not be less than 40 lb. to the yard. Now the form of the 

 remaining part of the rail will depend upon the manner in which it is to be 

 fastened down to the support below, either by being fixed in a chair, which 

 is itself to be again fastened to something else, or by being scre^ved down, 

 as the rails on the Great Westtrn. Croydon, and the new part of the Green- 

 wich Railway ; or, finally, secured in the simple manner described in the 

 last lecture. A comparatively very small addition to the theoretical form of 

 rail to be sustained in a chair, gives a section which has the advantage nf 

 being capable of being turned in either direction, or vertical position, and 

 hence the top and bottom of the rails have, of late, as previously stated, 

 been made equal and similar, connected by a neck of proportionate dimen- 

 sions. With the present heavy rails, of nearly SO lb. to the yard, the average 

 weight of the chairs, including the joint chairs, may be taken at 20 lb. per 

 yard, reducing the intervals of support to that constant distance. Thus, we 

 have an aggregate of nearly 100 lb. weight of iron per yard of each single 

 rail. If, then, we could in any way get rid of the extra weight required to 

 fasten the rail into the chair, and dispense with the chair altogether, it seemed 

 to Mr. Vignoles to be desirable to do so, provided the object in view was 

 equally well attained ; and he contended that such would be the case with a 

 50 lb rail attached, in the mole before described, to a longitudinal bearing 

 ,of timber; for the whole strength of the upper or bearing part would be 

 retained, that being as the breadth and the square of the depth ; thus, with 

 a weight of iron just one-half, would be equally efficacious, and it only 

 remained to compare the supports in either case. Now. as stone blocks 

 seemed to be discarded by universal consent, the question of the supports 

 below is narrowed to that of transverse or of longitudinal wood sleepers. 

 Sufficient experience had been obtained to warrant the conclusion that, lor 

 the purposes of this argiunent, the cost of fastening and of laying the rails, 

 ballasting, drains, Sec., taken as a whole, were nearly the same for both sys- 

 tems^ and it only remained to contrast the quantities of timber, and, always 

 considering a locomotive line to be the one to be made, it may be stated that 

 this cubing was about double for the longitudinal system to that in the 

 transverse method of laying the sleepers. In short, looking at first cost 

 only, there was a saving of 100 lb. of iron, and an increase of two cubic feet 

 of timber in each yiird of single trackway of the former over the latter mode. 

 so that strictly the longitudinal system was the cheapest ; but to avoid minor 

 objections, let the cost of each be taken to be the same, which was giving a 

 decided concession in favour of the transverse system. But this was a very 

 narrow view to take of the question, which wholly omitted the economical 

 results from diminished wear and tear of the engines, of the railway, and of 

 fhecaiTinges.ashad been most especially exemplified on the Dublin and Kings- 

 'town Railway, where the massy granite blocks originally laid down had been 

 all replaced by longitudinal sleepers, and though the old light 45 lb. rails and 

 151b. chairs were retained, the diminution of the annual maintenance was 

 most remarkable, though there was not a railway in the United Kingdom 

 where so many passengers were carried daily throughout the year. 



The expense of keeping up the double way, now that the system of longi- 

 tudinal timUrs has been quite carried out, is less than one-third of the 

 corresponding expense per mile per annum of maintaining the London and 

 Birmingham Railway. Mr. Vignoles then read a variety of tabular results 

 of the cost of the three various systems, going through all the details, and 

 pointing out the exact measures and quantities, and stating the actual expen- 

 diture on the upper works of various lines of railway. The result seemed 

 bed of the road was duly prepared, including all the items under that 



that, for a double line of railway— upper-works, properly laid after the 

 head, which were enumerated in a former lecture, and calculating, for the 

 present heavy and powerful locomotive engine, that no less a sum than 

 £5000. and, in most cases, £6000, per mile was necessary, and that, in many 

 instances it had reached nearly £7000 — the market price of iron and timber, 

 also the quality of the latter, the greater or less facility of obtaining materials 

 for ballast, &c.. affecting the amount, and these large sums were inJependent 

 nf the earthwork, masonry, land, fencing, management, stations carrying 

 establishment, &c. Mr. Vignoles also gave a number of drawings and 

 diagrams contrasting the three systems, and exhibiting, in a very explanatory 

 manner, the modes of laying and fastening. He also exhibited the rail, chair, 

 and fastenings, for the transverse method, wiih all the recent improvements 

 introduced by Mr. Cubitt on the .South-Eastern Railway, and as manufac- 

 tured by Messrs. May, of Ipswich, and then produced the rail with the 

 dove-tailed slot, and the mode of attachment to longitudinal half baulks of 

 timber. rei>eatedly alluded to in this and the preceding lecture, observing 

 forcibly, that, if the same effective results were obtainable by the latter 

 simple method as by the former comphcated one. it H:as not only to be pre- 

 ferred in this kingdom, but was peculiarly eligible for such countries as 

 Russia, Poland, Germany, in general, France, and America, where wood is 

 usually in great abundance, and where iron is comparatively scarce, especially 

 in the form required for railway bars, and, of course, the prices became in 

 proportion. Mr. Vignoles quoted largely from the works and reports of 

 Tredgold. Barlow, and Lecount, and stated a number of mathematical and 

 empirical rules laid dov\n by those authors, which, he stated, were chiefly 

 relating to rails supported at intervals, but. though he felt it right to lay 

 them before the class, he considered that tardier experiments and investiga- 

 tions were requisite, and particularly in reference to the perfect combination 

 in one support of the iron and timber in the longitudinal system, as explained 

 and avocated by him, of which the Professor insisted, the great advantage 

 and peculiarity was that of obtaining a perfect fastening, independent of 

 the fibre of the wood, or the tenacity of the screws or bolts therein, and of 

 obviating the hitherto well-founded objections to the mode of attaching rails 

 having a continuous bearing, which had not been able to prevent a vertical 

 play of the iron on the timber. 



PUOCEEBISIGS OP SCIENTIFIC SCCIIITXES. 



BRITISH ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE. 



Twelfth Meeting, 1842. — Held at Manchester. 



(Continued from paye 277.J 



Report on Experiments on the Transverse Strength of hot and 

 COLD BLAST Iron. By Mr. Fairbairn. 



The bars, as described in the former reports, were supported by standards, 

 4 ft. G ill. apart, and were loaded with different weights ; they were occa- 

 sionally carefully exaiuined, and showed a very slight progressive deflection. 

 He had no doubt that they would ultimately break, but the progress was very 

 slow. He read a table showing the weights laid on, and the deflections 

 of each bar. — Mr. Hartopp said, that i!r. Fairbairn's former experiments 

 ou hot and cold blast iron had created a false impression with regard to the 

 strength of hot blast iron. Jlr. Fairbairn had found very little difference 

 between the hot and cold blast ; but his experiments, made with great 

 accuracy, and in which the weights were laid on with great care, were of 

 little practical advantage, as these were not the circumstances under which 

 iron was tested in practice : there percussion, violent and sudden impact, 

 should be expected, and here lay the great deficiency of hot blast iron. Even 

 in Mr. Fairbairn's experiments, Oldberry No. 2, cold blast, bore twice the 

 percussion of Oldberry hot blast ; and Milton hot blast was only half the 

 strength of Elsicar cold blast, made of the same ore and smelted with the 

 same coal. Experiments had been made in Yorkshire with great care; the 

 results being. Low Moor cold blast bar iron, 3 in. diameter, broke with 6 

 blows, ditto Scrap, 3 blows, ditto hot blast, 1 blow ; again. Low Moor cold 

 blast 18 blows, Bierly ditto, 18, hot blast of as good materials, 3 bio— s; 

 again, Elsicar cold blast, 21 blows, Milton hot blast, IJ blow ; therefore, ia 

 iron for axles this ditference of at least five-sixths of the strength was very 

 important. .\s to scrap iron, it bore too high a character. Scrap, made on 

 the old plan, was all charcoal iron, but the modern scrap iron was very 

 inferior, being 32s. 6d. per ton cheaper, so that ironmasters put off as much 

 of this cheap material as possible. Hot blast iron was rejected now for 

 water-pipes, &c., and even for cannon balls ; and, in flue, he had been told 

 by very eminent marine engine makers, that where any percussion took 

 place, hot blast cast iron was only half the strength, and wrought iron only 

 one-sixth the strength of cold blast. 



Mr. Fairbairn explained, that he had found great difficulty in obtaining 

 specimens from the ditferent iron-masters, who would of course send, when 



