IN THE ANIMAL ORGANISM. 247 



The force available for meelianical purposes in an 

 adult man is reckoned, in mechanics, equal to ^th 

 of his own weight, which he can move during eight 

 hours, with a velocity of five feet in two seconds. 



If the weight of a man be 150 lbs., his force is 

 equal to a weight of 30 lbs. carried by him to a 

 distance of 72,000 feet. For every second his 

 momentum of force is = 30x2-5 = 75 lbs.; and for 

 the whole day's work, his momentum of motion 

 is = 30 X 72,000 = 216,000. 



By the restoration of the original weight of his 

 body, the man collects again a sum of force which 

 allows him, next day, to produce, without exhaus- 

 tion, the same amount of mechanical effects. 



This supply of force is furnished in a seven hours' 

 sleep. 



In manufactories of rolled iron it frequently hap- 

 pens, that the pressure of the engine, going at its 

 ordinary rate, is not sufficient to force a rod of iron 

 of a certain thickness to pass below the cylinders. 

 The workman, in this case, allows the whole force 

 of the steam to act on the revolving wheel, and not 

 until this has acquired a great velocity does he bring 

 the rod under the rollers ; when it is instantly flat- 

 tened with great ease into a plate, while the wheel 

 gradually loses the velocity it had acquired. What 

 the wheel gained in velocity, the roller gained in 

 force ; by this process force was obviously collected, 

 accumulated in the velocity ; but in this sense force 

 does not accumulate in the living organism. 



