56 AGRICULTUKAL ENGINES. 



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. 

 Kichards' 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 particu- 

 larly how you are getting on, and when you are likely to finish 

 the engines ordered. 



B. 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 tbe foundation of a bridge at 

 Exeter; but before sending it to its destination, lie 

 had arranged to plough with it, as a means of perfect- 

 ing the plans and drawings for a more suitable plough- 

 ing 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 

 through 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, 



