It is also an important matter to determine the de scription or form of rails best adapted to the roads. These are chiefly of two kinds, the plate and the edge the former represented in Plate CCCCLXXVII. Figs. 1, and 2. is always made of cast-iron. In Fig I. abbe is a plan, and Fig. 2. a section of the Plate rail; with a saddle piece, a c, shown in Fig. 1. which has lately been int•oduoed by Mr. Wilson of Troop, the more effectually to command the joint. The crest or flange b 6, in Fig. 2. gives strength to the rail, and is intended as a guide to keep the wheel b d in its place. From the mode in which the strength is applied in this description of rail, it must evidently require a propor tionally greater weight of metal to sustain the same load than the edge-rail represented in Figs. 3. and 4. in which the rail b c is set on edge on the principle of joisting in house carpentry. The plate-rail is also liable to be rutted or worn unequally, as will be obvious on examining the action of the wheel c e d upon the plate of the rail a b, Fig. '2. which, from the situation of the rail, is much exposed to work among (lust and small stones, to the great disadvantage of the load, whereas, the wheel c g h, Fig. 3. adapted to the edge-rail, is much less exposed to accident from adventitious mat ters. It has been observed of the wheels of the edge rail, that the rim c h is liable to wear unequally. This is, no doubt, an objection, but the evil does not seem to be remedied by the use of the plate-rail, the surface of which, as before noticed, is apt to be rutted, so that the rails, when worn in this manner, must be lifted and replaced by an operation greater, and ultimately more expensive, than the occasional renewal of a wa gon wheel.
It is believed that one of the chief advantages ori ginally expected from the use of the plate-rail, was the prospect of employing the cart in common use upon it, as well as the wagon expressly constructed for the railway. This would certainly, in many instances, prove a great convenicncy, but in others it would prove a waste of labour. As for example, the horse and man which brought a full load to town, could not ac complish its delivery. The adjustment of the wheels of a carriage, intended for the common road, is also dif ferent from that suitable for the railway, so that where ever this has been attempted, it has been found highly prejudicial to the road. It seems, therefore, better, up on the whole, to suppose the traffic to be carred on in wagons specially constructed for the railway. In the delivery of coal and such articles, an arrangement might be made for lifting the body of the wagon upon the wheels of a common cart, and so to be conveyed to the houses of the consumers.
To lay rails in a proper manner so as to prevent their getting loose, and thereby forming an irregular track, it has long been a desideratum to preserve their connected form, and at the same time to provide some what for the expansion of the metal. The edge, as well as the plate-rail, is often so injudiciously laid, that the surface of the track is kept too nearly upon a level with the horse-path, and the wheels are thereby con tinually exposed to work in mud. This earthy stuff
ing, in many instances seems to be pertinaciously preserved round the rails, though it cannot be sup posed to add in the smallest degree to their stability. It seems therefore much better to keep the rails wholly above the level of the horse-path, without the use of sleepers or cross-bars, a construction which may be termed a Skeleton Railway. The rails are thereby set above the road, and being completely exposed, ad ditional facilities are afforded for drainage and repairs. This mode of laying rails has been used with advantage in various situations, particularly at Lord Elgin's ex tensive lime and coal works. The iron chairs or guides into which the rails are fixed at the joints, and at regu lar distances between them, generally rest upon blocks or props, marked a c, Fig. L. measuring about- eight or ten inches square. In fixing pl/te-rails, a hole is per forated in the stone prop, and filled with an oaken plug. The ends of the plate b b are brought together, and a spike nail, with an elongated countersunk head is driven into the plug, and in this simple, but not very effective manner, the connexion is formed and the joints kept in their places, to which the addition of the saddle-piece, before noticed as in use at the Troon, has been found a great improvement. In fixing the edge-rails, a great many methods have been adopt ed, both in the form of the joint and construction of the chair or bed. That represented in Figs. 3. and 4. while it provides for the expansion of the bars, seems to be as effectual and simple as any. Fig. 4. is an elevation of the edge-rail, showing the meeting of the two rails a b and a c at the point d, where a joint is formed and commanded by the chair a d a, in which an oblong square hole is formed through which a strong iron spear bolt is driven, as shown in the section a b c Fig. 3. These chairs are placed at distances suited to the strength of the rail, and it seems proper that at least three should be allowed to each fathom of rail, every alternate chair to have a spear-bolt, one being always introduced at the joints.
It has lately been proposed by Mr..Palmer, civil engi neer, to erect a single rail, supported upon standards of timber, metal, or masonry, according to circumstances. Upon this rail the load is to be contained in a sort of ba lance wagon, having a receptacle on each side of the rail, on which it is to be suspended on the axles of two wheels, placed the one before the other. In the descriptive account of this railway. Mr. Palmer has given many useful remarks upon railways in general ; and dis cusses the difficulties to which the use of a single track is incident, in a very distinct and candid manner. In stead of square blocks of stone for supporting this single rail, he proposes to use stakes of timber or cast-iron, the downward ends of which are to be of a tapering form, and notched in such a manner as to give resistance to the pressure, a prop which, in many situations, may be found convenient and suitable.