Sufficient credit, moreover, has hardly been given to the canal system for the important part which it has taken in opening up the resources of different countries, and thereby bringing about the remarkable development of commerce and industry which has been so marked a feature of our own times. The Act for the construction of the Bridgwater Canal was obtained in 1759, previous to which time the internal commerce of the country, as we have seen, was carried on by pack-horses or waggons, on common turnpike-roads. Mr. Wood has calculated[25] that the average cost of conveying heavy goods on macadamised turnpike-roads by this system was 8_d._ per mile, while light goods cost 1_s._ per ton per mile. As that calculation applies to a time when wages, fodder, and other items involved in the expense of such transport, were lower than now, it is a fair assumption that it will be at least as much to-day, and for facility of reckoning we may take the average at the convenient and fairly likely figure of 10_d._ per ton per mile over all. Now, the total quantity of merchandise carried on the railways of the United Kingdom in 1887 was about 269 millions of tons. No evidence exists as to the total mileage over which this vast tonnage was carried, or, as it is expressed in railway phraseology, of the ton-mile traffic. But if we assume that the average charge for traffic carried by railway in 1887 was 1_d._ per ton per mile, the total movement would be represented by the enormous figure of 8962 millions of ton-miles. To have carried the same traffic under the system of transport that preceded the canals would have been impossible, but it would have cost the country, if it had been practicable, no less a sum than 373½ millions sterling, which is about one-third of the estimated amount of our national income from all sources. But this, after all, is not the most curious part of the calculation. In order to understand how impossible our present transport system would have been under the old _régime_, we must assume that a horse is capable, under ordinary circumstances, of carrying one ton about ten miles a day. Working for 300 days a year, therefore, he would be able to carry a total weight of about 3000 tons one mile in the course of twelve months. To undertake the same work as that performed by our railways would therefore require close on three million horses, or, practically, the whole of the horses that exist in the United Kingdom at the present time, for every purpose, including agriculture.