It will thus be seen that, whilst the coalowners introduced railways in the first instance, it was the canal companies themselves who, in the days before locomotives, mainly developed and established the utility of a new mode of traction which was eventually to supersede to so material an extent the inland navigation they favoured. It was open to those companies to adapt their undertakings much more completely to the new conditions, if they had had sufficient foresight and enterprise so to do. The signs of the times were obvious enough to those who were able and willing to read them, and there were many indications that canals would assuredly be not only supplemented, but supplanted, by railways. An impartial authority like Thomas Telford, in adding a postscript to an article on "Canals" which he had contributed to Archdeacon Plymley's "General View of the Agriculture of Shropshire," wrote under date November 13, 1800:-- "Since the year 1797, when the above account of the inland navigation of the county of Salop was made out, another mode of conveyance has frequently been adopted in this country to a considerable extent; I mean that of forming roads with iron rails laid along them, upon which the articles are conveyed on waggons, containing from six to thirty cwt.; experience has now convinced us that in countries whose surfaces are rugged, or where it is difficult to obtain water for lockage, where the weight of the articles of produce is great in comparison with their bulk, and where they are mostly to be conveyed from a higher to a lower {221}level,--that in those cases, iron rail-ways are in general preferable to a canal navigation. "On a rail-way well constructed, and laid with a declivity of 55 feet in a mile, one horse will readily take down waggons containing from 12 to 15 tons, and bring back the same waggons with four tons in them.... "This useful contrivance may be varied so as to suit the surface of many different countries at a comparatively moderate expense. It may be constructed in a manner much more expeditious than navigable canals; it may be introduced into many districts where canals are wholly inapplicable; and in case of any change in the working of the mines or manufactures, the rails may be taken up and put down again, in a new situation, at a moderate expense." Thomas Gray, writing in 1821, warned investors in canal shares that the time was "fast approaching when rail-ways must, from their manifest superiority in every respect, supersede the necessity both of canals and turnpike roads, so far as the general commerce of the country was concerned." He further expressed the conviction that "were canal proprietors sensible how much their respective shares would be improved in value by converting all the canals into rail-ways, there would not, perhaps, in the space of ten or twenty years remain a single canal in the country."