d(i 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



i Mabch, 



The time of working, corresponding to this average is 13 hours. 

 The weight on the safety-valve is 44 Ih. per square inch. 



Tlie engines and machinery at Bhickwall are similarly arranged, 

 hut on a smaller scale. The railway there passes hy the side of 

 the engine-house on the ground, and therefore the ropes are 

 gathered on at the lowest part of tlie circumference of the drums, 

 instead of at the highest part, as at the Minories, where the 

 railway passes over the engine-house. The engines, constructed 

 hy Mr. Barnes, are of the marine side-lever form, of the nominal 

 forces of 70 horse-power each, the pistons are 45| inches diameter, 

 vflth 4 feet stroke, and their average speed is 25 strokes per 

 minute. The large spur-wheels are 17 feet diameter to the pitch 

 line, with 120 teeth, 5^ inches pitch, and 14 inches hroad, working 

 into mortice spur-wheels on the axes of the drums, 10 ft. 10 in. 

 diameter, witli 80 wood cogs. The drums are 16^ feet diameter 

 when empty, and 22 feet diameter outside. The small steam- 

 engine for working the air-pumps, is 8 horse-power ; it was con- 

 structed by Messrs. Miller and Ravenhill. 



Remarks made at the Meeting after the reading of the above Paper. 



Mr. Farey stated that the wire rope consisted of six strands, each of sis 

 wires, coiled round a hempen core, and the whole of the strands were also 

 laid round one centre core of hemp. Wherever the wires were in actual 

 contact with the core, corrosion appeared to take place, which of course 

 augmented the rapidity of the destruction of the rope. It was, however, 

 now merely a question of expense, as, since the adoption of the wire rope, 

 hi-eakage seldom occurred. He thought that the old hempen rope had fre- 

 quently been broken by the undue strain which was suddenly brought upon 

 it, by its slipping on the drum. He imagined that a modification of the 

 method used in cotton spinning for regulating the coiling of the filaments, 

 might be adopted with advantage, instead of as at present coiling it by 

 hand. 



Mr. Bidder said he had noticed the peculiar tendency of the hemp rope 

 to twist, which caused its frequent fracture. The first rope was 5^ inches in 

 circumference, with a lay of 41 inches ; this was soon diminished to 3 inches, 

 and it broke continually. It was replaced by a rope from which the tar had 

 been expelled hy pressure; that was soon worn out, and the fibie appeared 

 completely destroyed. Wire ropes of various kinds were then tried ; and at 

 last, by the introduction of swivels, and recently by an improved construc- 

 tion of them, the bad effects of the twisting were obviated, although it still 

 took place. la spite of the rapid destruction of the hemp rope, he was of 

 opinion, that as a mere question of cost, it would be found cheaper than 

 wire rope, as, when partially destroyed, the former had still a certain value, 

 but the latter was comparatively valueless. 



Mr. R. Stephenson stated tiiat he was unable to account satisfactorily 

 for the twisting of the rope. He imagined that it might be caused, in some 

 degree, hy its being coiled over the drum at the Minories end, and under the 

 drum at the Blackwall end of the railway. The lateral action of the groove 

 of the inclined guide pulleys might also influence it, particularly on the 

 sharpest curves. Ropes composed of lengths, with a right-hand and a left- 

 hand lay alternately, had been tried, but inclTectually ; the twisting still con- 

 tinued, and the bad effects were only counteracted by the swivels. It might 

 have been imagined that the rope would have untwisted, and thus have length- 

 ened; hut, on the contrary, it became more tightly twisted, its diameter 

 diminished, and still its length increased, apparently from the pull of the 

 engines upon it. It was evident from the appearance of the fracture, when 

 one occurred, that the material was wrenched asunder by a twisting action. 

 The breakages occurred, however, very seldom at present; not oftener than 

 once or twice in a month, during which time nearly three thousand journeys 

 were made, and then they arose generally from the carelessness of the 

 hreaksmen, who, it must be remembered, received their instructions from a 

 distance of three miles, by the electric telegraph. The were six swivels in 

 the rope, one at every half-mile. The destructive effects of the twisting 

 would probably he diminshed by a larger number of ss\'ivels, hut they were 

 very objectionable, in preventing the regular laying of the rope upon the 

 drum. On the inclined planes in the north of England, where ropes had 

 been used for many years, this twisting was not ohserved ; hut there the 

 engines were at one end only ; whereas, on the Clackwall railway, the en- 

 gines at both ends working simultaneously, might probably have a tendency 

 to cause the twisting. Twenty years ago he had tried, in the North, ma- 

 chinery similar to that suggested by Mr. Farey, for laying the rope on the 

 drum ; but in consequence of the general diminution of diameter of the rope 

 from the stretching, and the inequalities occasioned by the splices, the ma- 

 chinery was constantly put out of order, and was eventually destroyed. On 

 the Blackwall line, the men had acquired considerable dexterity in directing 

 the rope with the levers or shears, and he thought it would scarcely be pos- 

 sible to improve that part of the system. — Some difficulty had been appre- 

 hended from the use of condensing engines, on account of the lime required 

 for forming the vacuum; it had, however, been met by having a small engine 

 constantly working to keep up the varuuni and to pump water. High- 

 pressure engines were generally used with rope traction, in order to avoid 

 this difficulty. He, however, preferred the use of condensing engines, with 

 a small supplementary engine, and believed them, at the same time, to be 

 jQve economical. 



Mr. A. WiGBTMAN stated that the wire rope was manufactured by Messrs. 

 Newall, of Gateshead, The wire was unannealed, and the weight of the 

 rope was 10 lb. per fathom, except two lengths of half a mile each, which 

 weighed 12 lb. per fathom; these lengths were so placed, that the main 

 trains to or from Blackwall, were always attached upon them. The swivels 

 were at first rivetted into the rope, but it was found that at least two-thirds 

 of the fractures of the rope occurred where the first rivet was inserted. In 

 order to prevent this, the swivels were spliced into the rope; this was done 

 hy unstranding about a yard and a half of the rope, passing the strands 

 tlirough an eye in the swivel, and then splicing them back into the rope. 

 Swivels thus inserted would last three months without renewing, and the lay 

 of the rope had been preserved ijy them. Breakages, however, still occurred, 

 hut (except from carelessness), they rarely, if ever, took place in a rope less 

 than a year old ; after that time the rope began to lose its strength, from 

 the oxidation that took place, wherever the strands came in contact with 

 the hemp core, and although a rope might appear sound after it had been 

 in use for a year and a half, yet on opening it, a considerable extent of oxi. 

 dation would he discovered. The rope-makers in the North attributed this, 

 in a great measure, to the serving of the rope with spun yarn, which bad 

 been adopted on the Blackwall railway, chiefly to prevent the noise occa- 

 sioned by the rope passing over the sheaves. Experiments were in progress, 

 with a view to doing away with the serving of tne rope, by covering the 

 sheaves with hard leather, which, if successful, would be the means of saving 

 the company a large expense in keeping up the serving, and would take a 

 weight of about 12 tons off the engines, and reducing also the cost of fuel. 

 With regard to hempen ropes, both tarred and white ropes had been tried, 

 but they had totally failed, some of them not lasting more than two months. 

 These ropes had a great tendency to twist, and from their bulk it was very 

 difficult to counteract it by the insertion of swivels. The wire ropes were, 

 consequently, the cheapest ; for although there was a difference in the ori- 

 ginal cost, as also on the return for the old ropes, yet the duration of the 

 wire rope was so much greater, that it more than compensated for the in- 

 crease in price. 



The charges for the motive power, for the year 1845, amounted to 

 ±"11,302 Is. Id.; during that time there were run 105 trains per day, 

 3J miles each, or 38,325 trains per annum, at an average cost of 5s. 10|<i. 

 per train, or Is. d^d. per mile. 



Although the present cost of working the line by the rope system was 

 high, yet by no other system had they been able satisfactorily to effect the 

 accommodation of stopping at the various stations, without iuterferiug with 

 the " through traflic." 



FOSSIL FOOTMARKS IN THE COAL FORMATION. 



Mr. Lyell delivered a lecture at the Royal Institution, on February 4th, 

 " On the Fossil Footmarlts of a Reptile in the Coal Formation of the Alleg- 

 hany Mountains. 



Mr. Lyell began hy observing that, notwithstanding the numerous re- 

 mains of land plants in the carboniferous strata and the evidence they afli'ord 

 of the existence of large tracts of dry land (the exact position of which is 

 often indicated by seams of coal and buried forests), no monuments of any 

 air-breathing creatures had been detected in rocks of such high antiquity 

 until Dr. King, in 1844, published his account of the foot-prints of a reptile 

 occurring in sandstone in Pennsylvania (see Silliman's Journal, vol. 48, page 

 343). These fossil tracks were found in a stone quarry five miles south-ea»t 

 of Greensburg, and about twenty miles east of Pntsburgh, appearing on the 

 under surfaces of slabs of argillaceous sandstone extracted for paving. They 

 project in relief, being casts of impressions formed in a subjacent layer of 

 fine unctuous clay, and they are accompanied by numerous casts of cracks of 

 various sizes, evidently produced by the drying and shrinking of the clayey 

 mud. These cracks occasionally traverse the foot-prints, showing that the 

 shrinkage took place after the animal had walked over the soft mud, and 

 before it had begun to dry and crack. Mr. Lyell exhibited a slab which he 

 had brought from the quarries, having visited them with Dr. King; and 

 then proceeded to point out the differences between these foot-prints and 

 those of the European cheirotherium found in Saxony and in Warwickshire 

 and Cheshire, always in the upper part of the new red sandstone or trias. 

 In the European hand-shaped foot-marks, from the form of which the ani- 

 mal was called by Kaup, cheirotherium, both the hind and fore feet have 

 each five toes, and the size of the hind foot is about five times as large as 

 the fore foot. In the American fossil the posterior foot-piint is not twice 

 as large as the anterior, and the number of toes is unequal, being five in the 

 hinder and four in the anterior foot ; as in the European cheirotherium the 

 fifth toe stands out nearly at a right angle with the foot, and somewhat 

 resembles the human thumb. On the external side of all the Pennsylvanian 

 tracks, both the larger and smaller, there is a protuberance like the rudi- 

 ment of another toe. The average length of the hind foot is bjg inches, and 

 of the fore foot 4j. The fore and hind feet being in pairs follow each other 

 very closely, there being an interval of about one inch only between them. 

 Between each pair the distance is six to eight inches, and between the two 

 parallel lines of tracks there is about the same distance. In the case of the 

 English and German cheirotherium, the hind and fore feet occur also in 

 j>airs, but they form only one row, in consequence of the animal having put 



