36 AGRICULTURAL ENGINES. 



CHAPTEK XVIII. 



AGRICULTURAL ENGINES. 



THE late Mrs. Trevithick said " that during the difficul- 

 ties in London in 1808 and 1810, when Trevithick was 

 overwhelming himself with new experiments and the 

 cost of patents, and law expenses, lawyers and bailiffs 

 took everything worth having from her house, including 

 account-books, drawings, papers, and models, which she 

 never saw again." 



His earlier account-books left in safety in his Cornish 

 home, though very disconnected, give trustworthy traces 

 of his work up to 1803. From that time only detached 

 accounts or papers are found until 1812, when the 

 unused pages in two old mine account-books of his 

 father served as his letter (rough-draft) books; and 

 judging from their number and style, his correspon- 

 dence was most extensive and varied. 



[Rough draft.] 

 " HAYLE FOUNDRY, February 13th, 1812. 



" To SIR CHRISTOPHER HAWKINS, Baronet. 



" Sir, I now send you, agreeable to your request, a plan 

 and description of my patent steam-engine, which I lately 

 erected on your farm for working a thrashing mill. The steam- 

 engine is equal in power to four horses, having a cylinder of 

 9 inches in diameter. The cylinder, with a moderate heat in 

 the boiler, makes thirty strokes in a minute, and as many 

 revolutions of the fly-wheel, to every one of which the drum of 

 the thrashing mill (which is 3 feet in diameter) is turned twelve 



