AGRICULTURAL ENGINES. 41 



engine for thrashing, chaff-cutting, sawing, &c. I am now 

 making one of about two-thirds the size of Sir Charles Hawkins', 

 which will be portable on wheels. By placing the engine in the 

 farm-yard, and passing the rope from the fly-wheel through the 

 barn-door, or window, and around the drum on the machine axle, 

 it may be driven. 



" The steam may be raised, and the engine moved a distance 

 of two miles, and the thrashing machine at work, within one 

 hour. 



" The weight, including engine, carriage, and wheels, will not 

 exceed 15 cwt. ; about the weight of an empty one-horse cart. 



" The size is 3 feet diameter, and (5 feet high. If you wish to 

 have one of this size sent to the Board of Agriculture as a 

 specimen, the price delivered in London will be sixty guineas." 



This engine differed from that referred to in the 

 drawing of Sir Charles Hawkins, mainly in the boiler 

 having the fire-place in the fire-tube, requiring no 

 brickwork, and having the advantage of portability. 

 It was very like the earlier locomotive boiler, except 

 that it was placed upright, as steam-cranes now use 

 boilers, instead of being horizontal. 



[Rough draft.] 



" CAMBORNE, CORNWALL, April 2Qth, 1812. 

 " To SIR JOHN SINCLAIR. 



" I have your favour of the 4th instant, informing me 

 that you had sent my letter respecting propelling ships by 

 steam to the Navy Board ; and also requesting a drawing and 

 statement of the thrashing engine to be sent to the President of 

 the Board of Agriculture, which shall be forwarded imme- 

 diately. 



" I beg to trouble you with a few wild ideas of mine, which 

 perhaps may some future day benefit the public, but at this 

 time remain buried, for want of encouragement to carry it into 

 execution. 



" The average consumption of coals in large steam-engines is 



