260 APPENDIX B. 



It is sometimes attained by engines of the Watt 

 type, but very rarely surpassed. This latter prod- 

 uct amounts, in French measures, to 104,000 kilo- 

 grams raised one metre per kilogram of coal con- 

 sumed. 



According to what is generally understood by 

 one horse-power, in estimating the duty of steam- 

 engines, an engine of ten horse-power should raise 

 per second 10 X 75 kilograms, or 750 kilograms, to 

 a height of one metre, or more, per hour; 750 X 

 3600 = 2,700,000 kilograms to one metre. If we 

 suppose that each kilogram of coal raised to this 

 height 104,000 kilograms, it will be necessary, in 

 order to ascertain how much coal is burnt in one 

 hour by our ten-horse-power engine, to divide 

 2,700,000 by 104,000, which gives *fiff- = 26 kilo- 

 grams. Now it is seldom that a ten -horse-power 

 engine consumes less than 26 kilograms of coal per 

 hour. 



