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104 THE CIVIL ENGINEER AND ARCHITECT’S JOURNAL. [April 1, 1868. arrangement by which it took the position of the ordinary rails, and laid flat. Mr. Alexander remarked that the expedients resorted to in the con struction of the engines had already been fully explained. In the plan of toothed gearing, first proposed by him for connecting the inner axles together, he found, as might be expected, a difficulty in getting the inner system to revolve. No apparatus was applied without first giving the opportunity to revolve. The engine was, in fact, tried with out spur-wheels in the first instance; but the axles refused to go round, and always came back again. lie then anticipated it would be a more simple affair to connect the wheels than it proved to be. With respect to the introduction of the toothed gearing, it was open to the objection that it made a great clatter when the engine worked off the mid-rail. He did not know that that was a fatal objection ; but it was at best a rough contrivance, which could hardly be tolerated in these days of mechanical perfection; and there was an objection to the clattering noise, because if the driver were accustomed to so much noise, he would be apt to disregard the noise occasioned by anything going wrong with the machinery. Many appliances had been suggested to connect these wheels, but serious difficulties arose from the fact that it was necessary to have variable distances between the axles. There was a continual and pro gressive wear going on at the tires. Also in running upon the mid- rail, which was tapered off to a fine point, the wheels receded from each other, and there was an immediate change of an inch or so in the distance of the centres. It was not like the ordinary coupling-rod sys tem, in which the wheels revolved at the same distances and in the same direction. The system shown in the model explained by Mr. Fell seemed to answer well, and on being tested proved efficient; but Mr. Alexander believed it could be simplified, the same principle being re tained. As this, however, had been so far actually tested, and its capabilities were known, and as it was difficult to predict what would be the results with an untried arrangement, it was proposed, in the engines now building, to use the method without alteration. With reference to the amount of power developed by these engines in proportion to their weight, he, having designed them, was sorry to say he could not agree with Captain Tyler as to the advantage to be de rived from the use of steel. He was anxious to use steel, as it was important that these engines should be as light as was consistent with safety. He had communicated with many Engineers in order to ascer tain what had been done in this direction ; but he did not find that in any articles subject to transverse torsional strain, with sudden shocks, like that upon axles, there had been any reduction of weight in conse quence of the use of steel; in fact there was sometimes an excess of weight, and he had been reluctantly compelled to abandon the use of steel under such circumstances. 11 is reason for that was that its ex tensibility was less than that of iron, its life was sooner exhausted, and it was more liable to give way under shocks. These engines were being made in France, where the use of steel was not carried so far as in this country, as there was not the same confidence in it; and there were many cases in which iron was used where, in this country, steel would have been employed. Mr. Mendes Cohen, of New York, would give the results of his experience in working the Baltimore and Ohio Railway, through Vir ginia. The gradients on that line were generally heavy. On the mountain division, 60 miles in length, there were 37 miles varying but slightly from 1 in 45, at which maximum there were 17 miles in one continuous gradient. The goods traffic was worked by engines weighing, exclusive of tender, about 27 tons, on eight connected chilled wheels 43 inches in diameter, with cylinders of 19 inches diameter and 22 inches stroke, hauling nine cars weighing about 135 tons. In addi tion to these there were other and much heavier gradients of a temporary character, adapted for the purpose of working over the tunnel ridges during the progress of the construction of the tunnels, to continue the line without waiting for the completion of the tunnel-work. In the first instance the gradient adopted was 1 in 10 as a maximum, and it was not intended to work this temporary line with locomotives. The line was built with a view of hauling car-loads of iron across the mountain by horse-power, and continuing the construction of the works on the other side. However, when the line was laid, it was de termined to try the working with locomotives. The engines just described were tried on this gradient and readily took up a load of one car weighing about 14 tons. Under favourable circumstances they could take up two, but one was the usual load. He had ridden over that lino on the engines but otherwise had not much experience in the working. As the construction of the line progressed westward, there was another tunnel on which he had been engaged as an assistant in the engineering department in the year 1852. Owing to delay in the tunnel, the Chief Engineer, Mr. Benjamin H. Latrobe, directed the construction of a temporary road across the hill. It was a work of some difficulty, as the slopes of the hill were very abrupt, and he was in structed by his chief to see what he could do in the way of bringing the line down from the summit to the foot of the hill, with a limit of gra dient of 1 in 16, and reversing the direction as often as was necessary. The descent of the summit on the western side w as made with five reversals, the narrowness of the ravines and the general shape of the ground not always affording room for curves of even the minimum radius of 300 feet. The reversal was effected by what wastermed a Y, from its resemblance in plan to that letter. With this arrangement the slope of the hill was descended on a gradient of 1 in 16 between one pair ofY’s, and 1 in 20 between the next pair, and so on alternately, the object of this being to secure the proper protection of the fire-box sheets, which might have been exposed had the rear of the engine been uppermost on the heavier gradient. The line was worked with five reversals on one side and two on the other for a distance of 2.*. miles on both sides of the hill, over which the engines carried three cars of 15 tons each. The load was never increased beyond that, because the shape of the ground did not admit of getting longer trains upon any of the Y’s. The traffic was carried on for five or six months, till the tunnel was completed. At a later period it was necessary, for a second time, to use the temporary track over the tunnel where the gradient of 1 in 10 had first been tried. On this occasion the gradient was re duced to 1 in 20, or equal to 260 feet per mile, and this Mr. Cohen himself worked with the same engines, which carried up from 65 to 70 tons load. In fact the whole traffic—mails, passengers, and goods—of one of the great American through lines was carried on by this way for many months during the arching of the tunnel. There was no difficulty in ascending the hill; the only difficulty lay in the descent. In effecting this, besides the application of breaks to all the wheels of the train, the engine was reversed and allowed to descend without using steam, thus pumping air through the cylinders. The accumulating pressure against the pistons was relieved by valves placed on the steam chests, and regulated from the foot-board. The engines were kept, on the heaviest portion of the gradient, on the lower side of the train, to guard against the breaking of the couplings, as well as with reference to the fire-boxes. There were some instances of the trains breaking away, from the failure of the breaks, and some little damage had been done; but no case of serious accident occurred during the whole time. Sir Cusask Roney said he could throw no light on the subject with respect to the engineering details connected with the crossing of moun tain passes by railways; but as the nature of his engagements for the last two or three years had taken him a great deal to Switzerland, and as he had been in constant communication with persons who took an interest in these matters, especially with reference to the passage of the Alps, he might be able to adduce a few facts of interest. The trade between Great Britain and the East was enormous; and it would be seen, by the table of exports and imports, that both the ex ports to the Eastern seas, and the imports from them amounted to about one-fourth of the gross trade of the United Kingdom. The Board of Foreign Trade of Great Britain in 1865, Exclusive of Specie. Imports. Exports. Tonnage of Ships. Inwards. Outwards. Total £ 271,131,967 £ 165,862,402 14,317,866 14,576,206 To and from Eas- ) tern Seas . . j 68,117,356 42,897,846 1,492,102 1,869,090 Trade returns showed that the value of the export trade for the year 1866, was £188,000,000, or an increase of about £23,000,000 com pared with 1865. No doubt the same proportion of increase existed with reference to the trade from the Eastern seas to Great Britain. It was, therefore, of the highest importance to this country to have the most rapid modes of conveyance for postal communication with those seas ; and no doubt the passage of the Alps by a railway would effect a complete revolution in the communication between Great Britain and the East. It would be seen by the table showing the distances in English miles between London and Alexandria, that a very small pro portion of the total distance via Southampton was by land ; while the London to Alexandria.—Distances in English Miles. Via. Land. Water. Total. Time. Southampton 75 3353 3428 Days. 15 Hours. 0 Marseilles 831 1701 2532 8 1 Brindisi . j Fast ) Mails ( 1482 977 2459 6 7 Ditto . . | Heavy ) 1482 977 2459 Ar 9 Mails j