VJb STRENGTH OF MEN AND HORSES. 



considerable ratio than the weight increases j and we may 

 therefore conclude, that it is advantageous to employ large men 

 when it becomes necessary to draw vertically from below 

 upwards j and, on the contrary, it is more advantageous to em- 

 ploy men of considerable weight, when it is required to lift 

 up loads by means of a pulley, about which a cord passes, 

 which the workmen draw in a vertical direction, from above 

 downwards. To find the absolute strength of these men in a 

 horizontal direction, I took the following method : 



Having fixed over an open pit a brass pulley, extremely well 

 made, of fifteen inches diameter, whose axis, made of well- 

 polished steel, to diminish the friction, was three-fourths of an 

 inch in diameter ; I passed over this pulley a silk cord worked 

 with care, to give it both the necessary strength and flexibility. 

 One of the ends of this cord carried a hook to hang a weight 

 to it, which hung vertically in the pit, whilst the other end was 

 held by one of the twenty men, who, in the first order of the 

 following experiments, made it pass above his shoulders j in- 

 stead of which, in the second, he simply held it by his hands. 



I had taken the precaution to construct this in such a manner, 

 that the pulley might be raised or lowered at pleasure, in order 

 to keep the end of the cord held by the man always in a hori- 

 zontal direction, according as the man was tall or short, and 

 exerted his strength in any given direction. 



I had made the necessary arrangements, so as to be able to 

 load successively the basin of a balance which I had attached to 

 the hook at the end of the cord which descended into the 

 pit, whilst the man who held the other end of the cord em- 

 ployed all his strength without advancing or retracting a single 

 inch. 

 Experiments The following table gives the weights placed in the basin 



with men put- w j ien t j ie workmen were obliged to give up, having no longer 

 ling horizon- . ° & r . V . , 



tally. sufficient strength to sustain the pressure occasioned by the 



weight. To proceed with certainty, I increased the weight 



each time by five pounds, beginning from 60, and intervals of 



time, having always precisely *a space often seconds between 



them. The result of these observations, repeated several days 



in succession, is contained in the following table : 



When 



