16 VARIOUS INVENTIONS. 



water. Cast-iron boilers dangerous. Wrought-iron 

 boilers to be tested with a water pressure four times as 

 great as the proposed working steam pressure. A 

 steam pressure of 20 Ibs. to the inch most suitable for 

 engines in charge of inexperienced persons. The 

 brewers' mash tub to be heated by the waste or surplus 

 steam. 



[Rough draft.] 

 " GENTLEMEN, " CAMBORNE, December 5th, 1812. 



"I have yours of the 20th November. The letter you 

 directed for Truro never came to hand. I find by your letter 

 that you have been trying to put into practice the hints I gave 

 you about the chain and buckets, and that you expect it will 

 answer if properly executed. You are not the first that has 

 picked up my hints, and stuck fast in their execution. I make 

 it a rule never to send a drawing until I have received my fee, 

 and when you remit to me fifteen guineas I will furnish you 

 with proper drawings and directions to enable you to make and 

 erect the machine. 



" I remain, Gentlemen, 



" Your very humble servant, 



"BICHARD TREVITHICK. 

 " ROBINSON AND BUCHANAN, Brewers, 

 "Londonderry" 



What a pocket encyclopaedia of inventions ! from 

 which, as by stealth, Robinson and Buchanan selected 

 the least applicable, declining a suitable steam-engine 

 at a very small cost, rather than pay an engineer for 

 his opinion. 



[Rough draft.] 



" CAMBORNE, April 26th, 1812. 



" SIR CHAKLES HAWKINS, Bart., 



" Sir, I have received yours of the 7th, respecting the 

 small breakwater at St. Ives. As far as I can judge from a 

 rough calculation, I think it an undertaking likely to pay well ; 



