AGRICULTURAL ENGINES 51 



and as the whole weight will not exceed If ton, I should hope 

 that the Commissioners at the Post Office will grant this request. 

 I am sorry to trouble you so often about my business, but I beg 

 the favour of your goodness to inform me through what channel 

 I ought to make this application. 



" I remain, Sir, 



" Your most obedient humble servant, 



"Ko. TREVITHICK." 



This experiment with the 1} ton portable engine 

 to travel from one plantation to another, needing 

 no condensing water, was certainly of the greatest 

 consequence to the planters in the West Indies, and 

 should have been of equal importance to tbe people in 

 England. 



Judging from the weight arid cost, as compared with 

 agricultural engines of the present day, Trevithick was 

 nearer the mark then than we are now ; its working 

 without condensing water the engineers of that day 

 believed to be impracticable, a fundamental error which 

 greatly retarded the use of the high-pressure steam- 

 engine. The providing sufficient condensing water 

 was often a most serious item of cost, and as water 

 mains were not in use, a deep well was a necessary 

 part of a steam vacuum engine. 



[Rough draft.] 

 " GENTLEMEN", " CORNWALL, CAMBOKNE, October IMk, 1812. 



" Yours of the 30th of September I found at my house 

 on my return yesterday from a journey. I am sorry to inform 

 you that Mr. Pickwood's engine is not ready. Near three 

 months ago I set my smiths and boiler-makers to work to com- 

 plete an engine for Mr. Pickwood, which parts were finished 

 five or six weeks ago. The other parts of the engine, which 

 were to have been made of cast iron, were ordered and com- 

 menced at a foundry in this county, belonging to Blewett, 



E 2 



