The origin of Railways may be traced back as far as the year 1680. About this time coal came generally into use as a substitute for wood fuel in London and other places; in consequence, the greatest inconvenience accrued at the mines in conveying the coals from them to the ships, and the expense of horses and machinery for the purpose was immense. To facilitate the travelling of the waggons over the dilapidated roads, wooden rails or straight pieces of wood were laid down and embedded in the road. These rails were afterwards improved upon by making ledges upon their sides, to prevent the waggons from going out of their track. By these simple contrivances it was also found that a waggon which required previously three or four horses to draw it, was with greater facility drawn by one horse, and in much less time, as the rails were laid upon a gradual descent. These wooden Rail-roads had been generally in use for fifty years, when cast-iron was introduced as a substitute, about the year 1738; but a difficulty arose in the great pressure of the heavy waggons then in use upon the iron. This was subsequently overcome by reducing the size of the waggons and linking a number of them together in a team, by which means the pressure was extended over a larger surface. The importance of Railroads becoming every year more manifest, several able treatises on the subject, from distinguished scientific men, appeared towards the close of the last century, setting forth their utility, and proposing plans for their improvement. After this time iron railroads began to be constructed as branches to canals, and in some places as roads of traffic from one place to another.