234 



STRENGTH OF MEN AND HORSES. 



Enler for de- 

 termining the 

 effects of ma- 

 chines moved 

 with diffeient 

 velocities, &c. 



Experiments 

 with men. 



Their sizes 

 and weights. 



ever it became necessary to compute the effect of a machine 

 moved by men or horses. It is evident that the force must be 

 diminished when the velocity is increased, and vice versa : but 

 we are not yet certain of the method of finding the ratio of 

 the diminution or augmentation of this force to the velocity. 

 Euler has given us two different formulae to compute this ratio : 

 but no one has hitherto attempted to verify by experiment which 

 of ihem is to be preferred, although they differ very conside- 

 rably from each other. If we put P for the absolute force 

 which takes place when we simply consider equilibrium, C the 

 absolute velocity which takes place when the man or animal 

 moves freely, and without being overcome by the resistance, 

 p the relative force, and c the corresponding velocity, we hav« 

 by the first of these formulas, 



2 

 j whereas the second gives usp= P (I 



C\ 



As I am obliged now more than ever to attend to a number 

 of machines, and to compute their effect, it therefore concerns 

 me very much to know exactly in what manner to estimate, 

 compare, and fix the strength and velocity of men and animals, 

 which are used for moving various machines, proper for diffe- 

 rent purposes. 



With this view I made, with considerable care, the experi- 

 ments I am now about to detail, which of course would have 

 been very expensive, had I not had some facilities which other 

 persons may not possess. 



To make the experiments on human strength, I took pro- 

 miscuously twenty men of different sizes and constitutions, 

 whom I measured and weighed 5 the result of which is given 

 in the following table : 



Wei glit. 





0% 



-) 



cv 



132 

 157 

 175 



192 



133 

 147 

 124 

 163 

 181 



