The Ferry of the Rhenish Railway GO/. 39, figs. on account of the shallowness of the river and the irregularities of its bed, has two wire-rope cables substituted in place of the chains; of these one of 1.8 inches diameter serves as a gnide-cable, and the other of 1.14 inches diameter serves as the working- rope. The guiding cable is passed over two guide-pulleys placed near the front and rear of the ferry-boat and slightly above the water-surface. It is held in place by anchor-chains attached at intervals of about 125 feet, their attachment to the cable being; made in such a manner as to interpose no obstacle to its passage over the guide-pulleys 16). The working cable is passed over two winding drums upon the ferry-boat, and these are set in motion by a small steam engine, and the working- rope, like the g-nide-rope, is fastened at the shore ends to a suitable anchorage. The section and plan views in Figure ,0 (pi. 39) illustrate this system very clearly.
Mode of Transfer on Railaw), Eerrics.—The means by which the cars are transferred to and from the terminal stations—always situated well above high-water mark—to the lower-lying boat's deck, the height of. which will vary according to the heig,ht of the water and the weight of the load it carries, may be classed as follows: (r) Those in which the difference in level is accommodated by interposed inclined planes; and (2) Those in which the difference in elevation is eliminated by raising or lowering the cars, by moving either the platform on which they stand or the boat itself vertically up or down, as may be necessary.
Tran.V.er by Inclined Plancs.—At the ferry of the Rhenish Railway com munication between the ferry-boat and the river-bank is established bv the intervention of inclined planes (incline, : 48), which are carried from the level of the terminal station to a point below low-water mark (pi. 39, figs. 15, 17). In this case the locomotive may be used directly to draw up the cars. A transfer platform or bridge mounted on wheels and running on the ordinary rails (fig. 17) is used for shifting the cars from the boat to the shore, and vice versa. In order that this connecting bridge may be kept as short as possible, it is g,iven an upward inclination toward the compara tively low-lying- boat's deck. Simple means are provided by which the
boat and shifting-bridg-e are held in position while the transfer is being effected. The locomotive is not permitted to run upon the bridge, and to avoid the necessity of this two empty cars are interposed between the loco motive and the cars to be transferred (jigs. T5, 17).
Transfer by Uerlical Alovcinents.—An illustration of the second order of transfer devices, in which the transfer is effected by direct vertical move ments, is afforded in the case of the railway ferry between Homburg and Ruhrort, where the cars are run upon iron platforms which may be raised or lowered through a distance of about 28 feet by hydraulic power. On the Lake of Constance another plan of this order is in use, in which the ferry-boat itself is raised or lowered, as may be necessary, by admitting or pumping out the needful amount of water-ballast. This plan is suitable only in situations where the alterations of the water-leyel are slig-ht, as in this case.
AI-amble-deck Transfer Feriyboal.—Fig,ure 2 (pi. 51) is a cross-section of a steam ferryboat whose deck, designed to provide for landing at any state of the tide, is capable of considerable movement. The usual movable landing,-stage is dispensed with; the deck of the boat is a platform operated bv six hydraulic elevators, by which it can be elevated or depressed, as may be required. The illustration shows the boat with the deck raised to the quay level at low tide. The landing- is made at the side of the boat, but the same principle could be applied to provide an end landing- should this be desirable.
Bridg-e Construction in Me Unilea' Slates.—In conclusion of this sec tion, the editor is enabled to append, on the authority of Thomas C. Clarke, an estimate of the total amount of bridge construction in the United States. It would be instructive to place beside this a similar estimate respecting bridge structures of European countries, but data for this unfortunately are not at this time accessible. Mr. Clarke estimates approximately that there are in the United States, at the present time (ISSS), 208,749 bridges of all kinds, having an aggregate length of 3213 miles. These are composed of