The sleepers in this description of road were generally formed of young sap lings, or strong branches of the oak, obtained by thinning the plantations, and were six feet long by five or six inches in thickness, and about the same breadth. At their first introduction, the under rail was of oak, and afterwards of fir, mostly six feet long, reaching across three sleepers, each two feet apart, and about five inches broad on the surface, by four or five inches in depth. The upper rail was of the same dimensions, and almost always made of beech or plane tree. The surface of the ground being formed pretty even, for about six feet in width from the pits to the staiths, or the whole length of the intended rail road, or "waggon-way," as it was termed, the sleepers were then laid down two feet apart, and the under rail properly secured to them. The ashes or material forming the surface of the ground, were then beat firmly against the surface of the rail, which was thus strengthened and made more rigid. The upper rail was then placed upon the other, and firmly bound down by the pins or pegs of wood...! This combination had many very obvious advantages over the single-rail; for, independent of the waste of timber before alluded to, the destruction of the sleepers in the single-rail by the feet of the draught-horses was considerable. The double-mil, by increasing the height of the surface whereon the carriages travelled, allowed the inside of the road to be filled up with ashes or stone to the under side of the upper rail, and consequently above the level of the sleepers, which thus secured them from the action of the feet of the horses. This description of railroad appears to have continued in use for a considerable period of time, especially amongst the collieries of Durham and Northumberland.
The waggons made use of were pretty nearly on the present construction, but sufficiently large to contain several tons of coal ; the wheels, called rollers by some authors, were exceedingly low, the smoothness of the road rendering high wheels unnecessary. An ordinary horse, on these roads, drew three tons of coals without difficulty to the driver. Where any declivity more than usually steep occurred, it was termed a run ; and whilst on it, the progress of the waggons was retarded and regulated by a species of crooked lever or brake, managed by the driver, and attached to the waggon. It is stated by some authors, that these wooden rails were subsequently improved upon by making ledges at their sides, to prevent the waggons from going out of their tracks ; a form which was subsequently given to them in cast-iron, and termed tram-plates, hereafter described. To avoid descending the steep declivities from the high banks at Newcastle to the river, staiths or high platforms are erected, projecting over the river, and so as to be nearly level with the banks ; whence the coal waggons are run by a very slightly inclined plane on to these staiths, and there dis charged through shoots or spouts, either directly into the holds of ships moored underneath, or info capacious intermediate reservoirs conveniently planned for the subsequent loading of ships.
In most cases the wooden railroads, from the mine to the place of shipment, were made so as to follow very nearly the undulations of the country over which they passed ; excepting only here and there at very steep ascents ; and for a long period of time no attempts were made to counteract the rapid descent of the carriages down the declivities, except by means of brakes, which, depend ing wholly upon the strength and dexterity of the waggoners, often failed, and were productive of many sad accidents. Sometimes, owing to the state of the weather, the rails became so slippery, as to render a suspension of the work unavoidable. Frequently, where very steep descents occurred, and a train of waggons were left on the declivity, owing to an obstruction caused by the weather, the falling of a shower of rain would release all the waggons together, and they would descend by their own gravity. Under such circumstances, men were employed to draw ropes across the line of road to arrest their progress ; and if this were effected before the momentum became considerable, any very great damage was thus prevented; but if the momentum were sufficient to break the ropes, serious disaster resulted. When cast-iron wheels were first introduced, they were only used for the fore-axle, the wooden wheels being retained on the hind-axle, from the idea that the brake could only be applied effectively to the wooden wheels. At length it was contrived, by an extension of the lever, to apply a brake to the metallic ; and then all the four wheels were made of iron. The next improvement was the adoption of iron for wood, which alone enabled the horse to take double his previous load. This change was not first introduced at Newcastle, as is generally supposed, but at the iron-works of Colebrook-dale, in Shropshire, about the year 1767. Our authority for this statement is derived from the reports of a Committee of the House of Commons, on the subject of roads and carriages. It occurs inci dentally in a letter to the Committee, from the ingenious Hornblower, the rival and contemporary of the celebrated Mr. Watt; who observes: " Railways have been in use in this kingdom time out of mind, and they were usually formed of scantlings of good sound oak, laid on sills or sleepers of the same timber, and pinned together with the same stuff: But the proprietors of Colebrook-dale Iron Works, a very respectable and opulent company eventually determined to cover these oak rails with cast-iron, not altogether as a neces sary expedient of improvement, but in part as a well-digested measure of economy in support of their trade. From some adventitious circumstances, (which I need not take time to relate,) the price of pigs became very low, and their works being of great extent, in order to keep the furnaces on, they thought it would be the best means of stocking their pigs, to lay them on the wooden railways, as it would help to pay the interest by reducing the repairs of the rails; and if iron should take any sudden rise, there was nothing to do but to take them up, and send them away as pigs.