tain the oil, or other lubricating matter, which, in the middle, is open to the upper side of the brass bearing; the oil being communicated to the axle by the two holes, shewn in the drawing. This chamber is covered, at the top, by a lid, 2 g, by which it can be filled with oil at any time. The spring, shewn at g g, Figs. 6 and 7, rests upon the chair, and is fastened to it by the same bolts which fasten the chair together, as shewn at g d, Fig. 6. Fig. 7, which is a plan of the bearing, shews the spring, gg; 5 and 6 being the bolt-holes for fastening the chair together, and also fastening the spring upon the chair. The middle compartment is the chamber, which contains the oil, with the hole through the brass of the chair, to lubricate the axle; the two side compartments, shewing that part on which the springs rest, with the bolt-holes, for fastening the springs to the chair. Vertical guides, similar to those shewn at ff, Fig. 10, are fastened to the side of the frame of the carriages; and the grooves, h h, Fig. 7, are cast for the guides to work in. Fig. 9, shews a plan of bearing, used on the carriages for the Newcastle and Carlisle railway, and is a vertical section, through the middle of the chair; e, being the upper side of the brass, and e', the under part. This chair is put together in two parts, meeting in the middle of the axle, and bolted together by two bolts on each side, as shewn at 1 1, Fig. 4. In this bearing, the spring does not rest upon the back, or upper side of it, as in Fig. 6; but the spring is placed above the frame of the carriage, as shewn in Fig. 10, with a bolt, 2′, passing through the frame, and resting on the upper side of the chair, by which the spring is acted upon by the inequality of the road. This bolt, resting upon the middle of the chair, prevents the possibility of a chamber in the middle for the oil, and there are, therefore, two chambers for that purpose,

one on each side of the part whereon the bolt rests; with two holes, 1 1, communicating with the brass of the bearing, and axle, for the oil to pass to the bearing part of the axle.

In the plan of bearing, Figs. 6 and 7, the guides are fastened to the outside of the framing of the carriage, and work within the grooves, hh, Fig. 7. In the plan, Fig. 9, the guides are made nearly the whole breadth of the chair, and work within the projecting parts, 3 3, 44, of the chair, Fig. 4. ff, Fig. 10, shew this plan of guides; one cheek of the guide, shewn by the dotted lines, projects upwards, on the inside of the frame, to steady it; and it is bolted upwards to the frame, by the bolts, a a, a a. The dotted lines, 3 3, 4 4, Fig. 9, represent the cheeks of the chair, within which the guides slide up and down; that part of the bearing on each side, projecting a little, as seen at c, in Fig. 10, and effectually acting as a guide for the chair to slide up and down. To secure the stability of the carriages, and counteract the twisting of the framing at the curves, it is very important, that the guides should be fixed, so that no working should take place, in the oscillation of the carriages, from one side to the other. Besides the bolts, cc, a stay, b, on each side, also passes between each guide, with a cross bolt between each sidestay, at b; a diagonal stay at each end, at dd, is also placed to steady the guides, and which likewise acts as braces to support that part of the framing of the carriage, which projects beyond the wheels.

The springs in Fig. 10, it will be seen, are placed above the frame of the carriage; that is done for the purpose of keeping the platform of the carriage as low as possible. If the springs were placed below the framing, or were made to rest upon the chair, as in Fig. 6, it would raise the frame, 44, so much higher, as would

be equal to the thickness of the spring. Another disadvantage of having the spring below the frame, is, that it increases the depth of the guides; and, of course, renders them weaker in resisting the side shocks, or twisting of the curves.

The bolt, 2, Fig. 9, passes through a hole in the frame of the carriage, and rests against the under side of the middle of the spring.

On all these bearings, it will be seen, that the end of the axle is increased in size, or that a collar is laid around the axle, so as to make it larger in diameter, than that part whereon the chair rests; this is done for the purpose of steadying the guides, or to prevent them from extending outwards, or in breadth. This has been found to be quite necessary, as some were tried upon the Newcastle and Carlisle railway without this collar, the guides and chairs of which, could not be kept at the proper width. We may here remark, that all these bearings are upon the principle of the wheels being fixed to the axle, and turning with them; which is the reverse of what is universally used on the carriages upon turnpike roads, where the wheels turn round upon the axle. In railway carriages, however, the depth of the flanch, to keep the wheels upon the rail, is only one inch; and it is necessary that no vibration of the wheel should exist, otherwise its liability to get off the rail would be greatly increased. In all bearings, similar to those used on common roads, some vibration exists, especially when they are a little worn; and the following trial will shew that the least vibration is injurious :-On the Newcastle and Carlisle railway some carriages were constructed, with the axles fitted into the nave of the wheel, in the same way as if they were to turn round with the wheels; except that, instead of the axles being keyed to the nave of the wheel at both ends, one of the wheels on each

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 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, c c, c c, 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, gg, and fastened to the two cross sheths, BB; the end of the bar, g g, passes into the double