23S 



STRENGTH OF MEN AND HORSES. 



against the 

 men. 



Having thus ohtained, not only the absolute force, but the abso- 

 lute velocity also, of several men, I took the following method 

 to determine their relative force. 

 The same with I had made use of a machine composed of two large cylin- 

 mtemnce ^ ers °*" ve, 7 narc * m arble, which turned round a vertical cylin- 

 der of wood, and moved by a horse, which described in its 

 march a circle of ten Rhinland feet. This machine appeared 

 to me the most proper to make the followi-ng experiments, 

 which serve to determine the relative strength that the men had 

 employed to move this machine, and which I use hereafter to 

 determine which of Euler's two formulas ought to be pre- 

 ferred. ' 



To obtain this relative force, I took here the same pulley 

 which served me in the preceding experiments, by applying 

 a cord to the vertical cylinder of wood, and attaching to the 

 other end of this cord, which entered into an open pit, a suffi- 

 cient weight to give successively to the machine different velo- 

 cities. 



Having applied in this manner a weight of 215lbs. the 

 machine acquired a motion which, after being reduced to an 

 uniform motion, taking into .account the acceleration of the 

 weight of the friction, and of the stiffness of the cord, gave 

 2*41 feet velocity 3 and having applied in the same manner a 

 weight of 220lbs. the resulting uniform motion gave a velo- 

 city of 2'47 feet. I only mention these two limits, because 

 they serve as a comparison with what immediately follows. 

 I began these experiments with a weight of lOOlbs. and in- 

 creased it by five every time, from that number up to 400lbs. 



I made this machine move by the seven first of my work- 

 men, placing them in such a way, that their direction remained 

 almost always perpendicular to the arm on which was attached 

 the cord which passed over their shoulders in an almost hori- 

 zontal direction. 



Thus situated, they made 281 turns with this machine in 

 two hours, which gave for their relative velocity c dc 2' 4.5 feet 

 per second. We have also the absolute force, or P, from these 

 seven men by the above table = 730lbs. and their absolute 

 velocity, or C = 5'30 feet. 



Therefore, by substituting these values in the first formula, 



we 



Results. 



