To one gentleman he said: “We want from the coal-mining, the iron-producing and manufacturing districts, a great railway for the carriage of these valuable products. We want, if I may so say, a stream of steam running directly through the country, from the North to London, and from other similar districts to London. Speed is not so much an object as utility and cheapness. It will not do to mix up the heavy merchandise and coal trains with the passenger trains. Coal and most kinds of goods can wait; but passengers will not. A less perfect road and less expensive works will do well enough for coal trains, if run at a low speed; and if the line be flat, it is not of much consequence whether it be direct or not. Whenever you put passenger trains on a line, all the other trains must be run at high speeds to keep out of their way. But coal trains run at high speeds pull the road to pieces, besides causing large expenditure in locomotive power; and I doubt very much whether they will pay after all; but a succession of long coal trains, if run at from ten to fourteen miles an hour, would pay very well. Thus the Stockton and Darlington Company made a larger profit when running coal at low speeds at a halfpenny a ton per mile, than they have been able to do since they put on their fast passenger trains, when everything must needs be run faster, and a much larger proportion of the gross receipts is absorbed by working expenses.” In advocating these views, Mr. Stephenson was considerably ahead of his time; and although he did not live to see his anticipations fully realised as to the supply of the London coal-market, he was nevertheless the first to point out, and to some extent to prove, the practicability of establishing a profitable coal trade by railway between the northern counties and the metropolis. So long, however, as the traffic was conducted on main passenger lines at comparatively high speeds, it was found that the expenditure on tear and wear of road and locomotive power,—not to mention the increased risk of carrying on the first-class passenger traffic with which it was mixed up,—necessarily left a very small margin of profit; and hence Mr. Stephenson was in the habit of urging the propriety of constructing a railway which should be exclusively devoted to goods and mineral traffic run at low speeds as the only condition on which a large railway traffic of that sort could be profitably conducted.