AGRICULTURAL ENGINES. 39 



ri^lit Trevitliick charged 15 per cent, for wear and 

 tear on the hor^e machinery, and but 5 per cent, on 

 the steam-engine ; overlooking the cost of the horses, 

 which would have made the outlay for the horses and 

 machinery greater than for the steam-engine. 



The whole design evidences simplicity and consequent 

 cheapness ; no complication of valves or valve-gear, no 

 cylinder cover, parallel motion, guide-rods, or air-pump, 

 \vith its condenser and injection- water. 



The 4-horse engine, with boiler complete, cost 90. 

 A common labourer worked it, and as it needed no 

 supply of feed-water during six hours of work, the cost 

 and attention of supplying feed were avoided. If a 

 supply was required during the day it could be given 

 by a pipe with two taps. 



This first use of steam in agriculture was immediately 

 followed by Lord Dedunstanville of Tehidy, Mr. Kendal 

 of Padstow, and Mr. Jasper of Bridgenorth. Sir Charles' 

 request for a more official report signed by disinterested 

 persons brought a reply that the thrashing engine con- 

 tinued to work well. " It far exceeds my expectation. 

 I am now building a portable steam-whim, on the same 

 plan, to go itself from shaft to shaft." " If you should 

 fall in with any West India planter that stands in want 

 of an engine, he may see this at work in a month, which 

 will prove to him the advantage of a portable engine 

 to travel from one plantation to another. The price 

 complete is 105/." 1 



' DEAR SlR, " ARGYLE STREET, ISth March, 1812. 



" I am sorry it is not convenient for me to advance you 

 tin- money for Wheal Liberty; adventurers having the dues 

 very low, ought to furnish the needful. I am very glad you Imve 



1 See Trevithick's h-tk-r, 10th March, 1SPJ, chap. xx. 



