THE ANIMAL AS A MACHINE. 



2,000,000 foot-pounds when ascending mountains, and 

 from 1,250,000 to 2,500,000 turning a winch. 



It is customarily assumed that a horse may develop 

 22,500 foot-pounds per minute throughout a day's work 

 of eight hours ; will carry 250 pounds 25 miles in a day 

 of eight hours; and that 1500 pounds, wagon included, 

 is a good load for a horse drawing it on good roads 25 

 miles a day of eight hours. The regular load rarely 

 exceeds one half the maximum. The load which can 

 be raised by a bird is said to be about one half its own 

 weight as a maximum. 



Weisbach states that a man can walk, unloaded, ten 

 hours a day at ^\ miles an hour ; carrying 80 pounds, 

 he can walk seven hours at two thirds that speed. He 

 can walk upstairs, unburdened, at the rate of 0.48 foot 

 per second, eight hours a day, and performing 1,935,360 

 foot-pounds of work per day, assuming his weight to 

 be 140 pounds. He can traverse, without load, 12.5 

 times as much space horizontally as vertically. A day's 

 work with a " rammer," such as is used by paviors, is 

 given as 1,142,400 ft. -lbs. Turning a crank, man accom- 

 plishes 1,175,040, with a mean effort of 16 pounds and 

 a speed of 2.4 feet per second during a working day of 

 eight hours. On a capstan an able-bodied man, also, 

 can perform 1,382,400 foot-pounds of work per day. 

 On the treadmill he attains 1,750,000 foot-pounds. 



The estimates of General Jouffret yield the fol- 

 lowing " According to the Guide Joanne, the ascent 

 of Mont Blanc, starting from Chamounix, is effected in 

 seventeen hours, resting-spells not included. The dif- 

 ference of level is 3760 metres. A person ascending 



* Theorie de I'Energie ; Paris, 1885. 



