V nAR y 



. 



-UNIVERSITY J 



^ " 

 CAL1FJ ~ 

 AGRICULTURAL El 



37 



times. The boiler evaporates 9 gallons of water in an hour, and 

 works six hours without being replenished. The engine requires 

 very little attention a common labouring man easily regulates 

 it. 



TREVITHICK'S HIGH-PRESSURE STEAM-PUFFER THRASHING ENGINE, 1812. 



" The expense of your engine of 4-horse power, compared 

 with the expense of four horses, is as follows : 



8. 



Original cost of the steam-engine . . 80 



Building material and rope 10 



Interest on the above 90?. at 5 per cent. 

 Wear and tear at 5 per cent 



Original cost of horse machinery for four horses . . 



Interest on the above at 5 per cent. 

 Wear and tear at 15 per cent. 



90 



4 10 

 4 10 



9 



60 



3 

 9 



12 



" Two bushels or 164 Ibs. of coal will do the work of four 

 horses, costing 2s. 6d. 



