side was not keyed to the axle, but was left at liberty to turn round it, for the purpose of trying the effect upon the curves; a groove being cut around the axle, in which the end of a pin worked, to prevent the wheel from working off. Although the hole through the nave of the wheel was bored out, and the axle turned, and made to fit as accurately as possible, still there was a trifling vibration of the wheel, when it turned round the axle, and this small vibration was sufficient to cause the carriages to run off the rails occasionally; the axles were then keyed to the wheel, and no such occurrence took place. From this experiment, it would appear, that it is quite essential to the safety of railroad travelling, that the wheels of the carriages should be fixed to the axles, and turn round with them. We are aware, that upon some railroads, though principally upon plate rails, the wheels are loose upon the axles; but on plate rails, the liability to run off the rails, is much diminished by the great height of the upright ledge; and upon those of the edge rails, the flanch of the wheels is made very deep, and the carriages travel at a slow rate. Having thus described some of the different plans of bearings, we shall reserve, for another part of the work, our enquiries into the best form and dimensions of the bearing part of the axle, to produce the least friction; and shall proceed to describe the different kinds of carriages for coals, heavy goods, and passengers, used upon the different railways. §7.-Modern Coal Waggons, or Carriages. Figs. 1, 2, and 3 shew the plan of waggons or carriages, used in the north of England for the conveyance of coals. The reason why they are made of this shape, is, that the coals are discharged out of the bottom of the carriage; and, therefore, it is necessary to have them narrower at the bottom than at the top, or in the shape of a hopper, that the coals may run out. In some of the railways in the south of England, and in Scotland, the coals are laid upon a waggon with a square body, the coals being in this case, lifted out by hand or by shovels; but, in the neighbourhood of Newcastle, this mode is too slow an operation; for the large quantities required to be constantly shipped. Fig.1, is an elevation; Fig. 2, a plan; and Fig. 3, an end view. The framework consists of the two side frames, or soles, A A, A A, as they are called, fastened together by the four cross sheths, B B B B, and the bolts, a a. Upright sheths, b b b b, are placed upon the side frames, and cross sheths, as shewn in the figures; and are made of wrought iron, rolled into the proper shape for the purpose. The lower ends of the upright sheths are bolted to the framing, A A, A A, by screw-bolts, that part, passing through the framing, being bevelled upright; when screwed down, they are fixed firmly into the timber. The top framing is also iron, rolled for the purpose, the side sheths being rivetted to the top frame; the ends and sides are then clead with deals, which are sometimes bolted to the upright sheths, but more frequently rivetted to them with small bolts. The upright sheths, and top framing, are sometimes made of timber, and either clead with thin sheet iron, or deals. The bottom, which consists of deals fastened together by the cross sheths, cc, cc, is hung upon two iron cross bars, ef, ef, working upon eye-bolts at the ends, e e, and is hung upon clasps at the ends, ff, for the purpose of being opened with facility, when the clasps are struck off. The waggons are dragged by means of a short chain, with a double eye at each end, attached to the middle bar, g g, and fastened to the two cross sheths, BB; the end of the bar, g g, passes into the double eye, and is secured by a bolt, as shewn in Fig. 3. A chain is not, however, always used; sometimes a bar of iron is substituted, which is fastened in the same manner. To add to the breadth of the ends of the side frames, a a, a a, and prevent the ends from passing each other, on the curves of the road, a piece of wood, ii, is bolted to the inside of the side frame, and secured by hoops, k k k k, passed around the ends. The break, or brake, is fastened to the side frame by a cast-iron stud, bolted to the framing, and shewn by the dotted lines at o, Fig. 1. A wrought-iron pin is keyed into this stud, on which the brake, or lever, m n r, works, the pin at o acting as its fulcrum. The part, mn, is a flat bar, to which pieces of wood are bolted on each side, for the purpose of nailing on the wooden brakes, pp, which press against the wheels. These brakes were formerly called " convoys," and were made of wood entirely; the pieces, pp, being called "breasts," and composed of beech. The end, r, is kept up by a bolt, when not used; and before self-acting planes were established, another lever, acting upon the end r, was applied, to increase the power. The dimensions of the waggons, here described, are such as carry about fifty-five cwt. of coals or, by heaping a little, nearly three tons. § 8.-Truck for the Conveyance of general Fig. 10, Plate VII., is a side view or elevation; Fig. 11, a plan; and Figs. 12 and 13, end views of a truck, or platform carriage, for the conveyance of general goods on public railroads. The main framing consists of the four longitudinal frames, 11, 22, 33, 44, which are fastened together by the three cross sheths, 55, 66, 77; P these sheths are mortised into the frames 11 and 22, and bolted to them by bed-bolts, and are likewise more firmly bound together by the long bolts, 5'5', 6'′6′, 7′7′′. This framing is still further strengthened, and prevented from twisting, by the diagonal braces, 88 and 99. It may here be remarked, that the inner longitudinal frames, 22 and 33, are not applied, except where carriages similar to those of Figs. 1, and 3, are to travel upon the same railway, or where carriages are used, with the bearings inside the wheels. In these cases, the inner frames are necessary to abut against the ends, k k, of the other carriages, unless the whole train be coupled together by inflexible bars, and thus prevent the ends of the carriages from abutting against each other. When the inner frames, 22 and 33, are not used, the diagonal braces must extend to the outer frames, 11 and 44. Upon this main frame, the upper framing, ii, kk, is raised, for the purpose of forming a platform, on which the goods are to be placed, and which is thus constructed:-Upon the outer frames, 11 and 44, and also resting upon the cross sheths, 55, 77, the cross sheths, ll, mm, are laid at each end, an end view of which is shewn in Fig. 12. Four cast-iron boxes, rrrr, are bolted down to the side frame, 11 and 44, on each side, shewn on a larger scale in Figs. 14, 15, and 16; Fig. 14, being an elevation; Fig. 15, an end view of the inner side; and Fig. 16, a plan. Upon the cross sheths, 11, mm, and the cast-iron stands, the longitudinal sheths, ii and kk, are bolted; another longitudinal sheth, o o, (broken off in Fig. 11,) is laid upon the cross sheths, 5, 6, and 7, and bolted to them; four cross sheths, n n n n, resting in the middle upon the last-named sheth, and with their ends upon the castiron stands, rrrr, as shewn in Figs. 11, 13, and 16, are then placed across, and bolted to the lower cross sheths. This frame-work is then covered with planks, shewn in Fig. 13, and made with a little depression in the middle, for the goods to lie more securely. It will be seen also, for the same purpose, that the outside longitudinal sheths, i k, project a little above the level of the cleading of the platform. At each end, a piece of timber, ss, Fig. 12, is laid across, and which is likewise raised a little above the level of the platform. The iron bar, by which the carriage is dragged, is shewn at e e, Fig. 11, and as it reaches the whole length of the carriage, and as all the cross sheths are bolted to this bar, it gives additional strength to the frame-work. These carriages, which are generally denominated "trucks," are used for almost all the different descriptions of goods carried upon railroads; and as they present, upon a railroad, four feet eight inches in width, a superficial surface of platform of seventy-five square feet, a considerable quantity of very light goods can be placed upon them. They generally carry about four tons weight, and by increasing the dimensions of the platform, this may be increased. § 9.-Common Passenger Carriages. Figs. 1 and 2, Plate VIII. shew the elevation and plan, of the frame-work of a carriage for the conveyance of passengers, the same figures being used to refer to the same parts, as in the previous drawings of the truck carriages; 11, 22, 33, and 44, Fig. 2, are the longitudinal sheths; and 55', 5", 66′ 6′′, 7, the cross sheths. The same inner longitudinal sheths, 22 and 33, are put in this drawing, as in that of Fig. 11, Plate VII.; but these |