[Rough draft.]
"Camborne, January 26th, 1813.
"Mr. Rastrick,
"Sir,—I have your favour of the 10th inst., in which you do not state the time when you expect I shall have either of the engines that you are executing. As so much time has elapsed since the orders were given, the persons that ordered them are quite impotent. The ploughing engine that I sent you a drawing for, after being tried for that purpose, was to have been sent to Exeter for pumping water out of the foundations of a new bridge; but as they intend to begin their work at the bridge before the end of March, the engine must be there before that time, or they will erect horse machines and not use the engine. I have therefore been obliged to send the small boiler that I had for that purpose to Hayle Foundry, and get the castings made there for this engine to get it in time to prevent losing the order. I have also been obliged to take the small portable engine from Wheal Alfred Mine and have new apparatus fitted to it, to apply this engine for Plymouth Breakwater. A small engine, from the same patterns as Sir Charles Hawkins' thrashing engine, which I had at work in a mine, I have been obliged to send to one of the farmers at Padstow for thrashing, instead of one of those engines that I ordered from you. I expect that the people who ordered the engine for the West Indies are also tired of waiting. I have two other applications for engines for the West Indies, and the Messrs. Fox will want a great many engines of that size for the Plymouth Breakwater. They are to provide machinery, with every other expense, and I am to have a certain proportion of what I can save over what it now costs them to do it by manual labour. I think I have made a very good bargain, for if the plan succeeds I shall get a great deal of money, and if it fails I shall lose nothing. They have engaged with the Government to deliver 3,000,000 tons, for which they have a very good price, even if it was to be done by men's labour. I hope I shall get the engine soon on the spot, and will then let you know the result. As the boiler that was intended for the ploughing engine is to be sent to Exeter, I wish you to finish that engine with boiler, wheels, and everything complete for ploughing and thrashing, as shown in the drawing, unless you can improve on it. There is no doubt about the wheels turning around as you suppose, for when that engine in Wales travelled on the tramroad, which was very smooth, yet all the power of the engine could not slip around the wheels when the engine was chained to a post for that particular experiment.
"That new engine you saw near the seaside with me is now lifting forty millions 1 foot high with 1 bushel of coal, which is very nearly double the duty that is done by any other engine in the county. A few days since I altered a 64-inch cylinder engine at Wheal Alfred to the same plan, and I think she will do equally as much duty. I have a notice to attend a mine meeting to erect a new engine equal in power to a 63-inch cylinder single, which I hope to be able to send to you for. I have also an appointment to meet some gentlemen at Swansea, to erect two engines for them, one to lift water, the other coal, which you will hear more about, I expect, soon. If I can spare a few days when at Swansea, I will call to see you at Bridgenorth. I have not seen Mr. Richard since you left, but will call on him in a few days and do as you request. If you think the fly-wheel is not sufficiently heavy for his engine, add half a ton more to the ring.
"If you cannot finish all these engines at the same time, I would rather the smaller ones should be finished first and Mr. Richards' stand a little, because if his engine was now ready he would not pull down his thrashing machine until he had nearly thrashed all his corn, and the machine now stands on the spot where the mill is to be erected.
"If I call on you from Swansea I think I shall be able to show you a new idea, which I think will, if carried into practice, be of immense value. Please to write to me and say particularly how you are getting on, and when you are likely to finish the engines ordered.
"R. T."
Trevithick had sent a drawing of a ploughing engine to Rastrick at Bridgenorth, that the castings might be made, while he himself was having the boiler and wrought-iron work constructed in Cornwall. The engine had been ordered as a portable pumping engine, for removing water from the foundation of a bridge at Exeter; but before sending it to its destination, he had arranged to plough with it, as a means of perfecting the plans and drawings for a more suitable ploughing engine then in construction, to be fitted "with boiler, wheels, and everything complete for ploughing and thrashing, as shown in the drawing." The friction of the wheels on the ground would be greater than the power of the engine; therefore they would not slip when the full power was applied to draw a plough any more than the Welsh engine, the wheels of which did not slip though resting on smooth iron.
One of his small engines, which had been at work in a mine, was sent as a thrashing engine to Padstow. It is evident that, having given a portion of his attention for a year or two to the question of steam agriculture, he had so far progressed in 1813 as to construct thrashing machines, portable agricultural engines, and steam-ploughs to be moved by wheels as in locomotives; reaping, sowing, and other work, was also in future to be the work of the steam-engine.