48 AGRICULTUBAL ENGINES. 



money to carry the plan fully into effect for propelling ships, for 

 travelling with weights on roads, and doing almost every kind 

 of agricultural labour. 



" But a patent is but for fourteen years, and open to constant 

 infringement ; for the inventor of general and useful machinery 

 is a target for every mechanic to shoot at, and unless protected 

 or encouraged by some better plan than a common patent, will 

 have the whole kingdom to contend with in law, and most likely 

 receive ruin for his reward, which has too often been the case. 



"A plan of such magnitude as this promises to be of, I think 

 ought to be carried into effect by subscription, and as soon as 

 accomplished, the subscribers to be repaid, and the invention 

 thrown open for the use of the kingdom at large. I think 

 about WOOL or 15001. would test the designs. 



" It is expected that Mr. Praed will spend some time in this 

 neighbourhood ; I hope I shall be able to prove to you and to 

 him the great use of propelling barges by steam. I have a 

 small engine now at foundry, and would put it on board one 

 of their barges for your inspection. I am very much obliged 

 for your continued favours, and beg pardon for so often troubling 

 you. I have so fully proved the great advantages resulting from 

 those portable engines, that I very much wish the public to 

 have the full use of them. 



" I remain, Sir, 



" Your most humble servant, 



" RICHARD TREVITHICK." 



A 12-mule-power engine for St. Kitts was being 

 erected at Harvey's foundry at Hayle ; Trevithick 

 making himself liable for the whole cost, in case it 

 should not answer the purpose. The mules thrown 

 out of work by the engine would sell for five times as 

 much as the engine cost, to say nothing of the saving 

 in wear and tear of drivers and mules, and the un- 

 pleasantness of driving a mule in hot weather as 

 compared with a machine. 



