THE ANIMAL AS A MOTOR. 



57 



who has a mean weight of 70 kilogrammes produces, 

 then, in order to rise, a work of 3760 X 70 = 263,000 

 kilogrammetres. This work is borrowed from the heat 

 that the carbon and hydrogon contained in the food 

 eaten disengage upon being burned in the lungs. For 

 the sake of simplicity, if we reduce the entire energy to 

 a combustion of carbon, and recall that a kilogramme 

 of the latter furnishes 3,000,000 kilogrammetres, we find 

 that the 263,000 kilogrammetres represented by the 

 ascent correspond to a consumption of 94 grammes of 

 coal — a consumption that should be added to the 

 normal rations necessary for the operation of the organs 

 during a state of rest. Such consumption is 8.35 

 grammes per hour, or 142 grammes for the seventeen 

 hours. The total consumption of coal is 256 grammes, 

 representing 708,000 kilogrammetres. The perform- 

 ance, then, is 



263,000 



— ^ =. 37 per cent. 



708,000 ^ 



**The performance of the human machine drops to 

 21 per cent when we consider a period of twenty-four 

 hours composed of ten hours of work and fourteen of 

 rest, and a mean daily work of 280,000 kilogrammetres. 



" The cannon, considered as a machine, is incompar- 

 ably superior to a steam-engine as regards the time 

 necessary to produce a given quantity of mechanical 

 work. 



"Thus, for example, the lOO-ton cannon develops in 

 one hundredth of a second a quantity of work equal to 

 that which would be yielded by a 47-horse-power steam- 

 engine in one hour. A man of average strength is still 

 lighter than an ordinary steam engine of equal power, 



