NOTE BY W. FAIRBAIRN, F.R.S. F.G.S. 485 



Nominal Power of living 



Engines. Horse-power. Horses required to do 



the same work. 

 283 for pumping and blowing 11,247X4 44,988 



805 rotative . . .12,618X3 37,854 



76 boat engines . . 2,080X3 6,240 



1,164 25,945 89,082 



"And between January 1824 and January 1854, the num- 

 bers are the following : — 



34 for pumping and blowing 2,403X4 9,612 



164 rotative . . . 7,517X3 22,551 



243 boat engines . .15,358X3 46,074 



441 25,278 78,237 



1,605 51,223 167,319 



" The first engine seems to have been made for Bedworth, 

 in 1776." 



It will be noticed that for pumping engines the nominal 

 horse-power is multiplied by four to give the real horse-power 

 required to do the same work in the same time ; and this is 

 on the supposition that a horse can work only six hours a day, 

 whilst the engine can work twenty-four. But in rotative en- 

 gines an allowance has been made in the above table for loss 

 of power in the action of the crank, &c. as compared with the 

 direct action in the other case, and the nominal horse-power 

 is multiplied by three only. 



Perhaps it would be more accurate to suppose that a horse 

 can work for eight hours out of the twenty-four ; but at the same 

 time to multiply the nominal horse-power by two, because 



