Men and Horses in moving Machines. 287 



march with a good pace but without running, and so as to 

 continue during the space ot four or five hours; tlie fol- 

 lowing is the tHDe employed in describing this space, with 

 the velocit} resulting for each of them. 



It is necessary to mention with regard to these experi- 

 ments, that I took care to place at certain distances per- 

 sons in whom I could place confidence, in order to observe 

 whether these men marched uniformly and Sufficiently 

 quick, without running. 



Having thus obtained, not only the absolute force, but 

 the absolute velocity also, of several men, I took the fol- 

 lowing method to deternune their relati\e force. 



I made use of a machme composed of two large cylin- 

 ders of verv hard marble, which turned round a vertical 

 cylinder of wood, and moved by a horse, which described 

 in his march a circle of lu Rhmland feet. This machine 

 appeared to me the most pro|)er to make the following ex- 

 periments, which serve to determine the relative strength 

 that the men had eniploved to n)ove this machine, and 

 which I use hercatter, to dett-rmine w hich of Euler's two 

 formulae ought to be preferred. 



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

 which servtd me in the precedmg experiments, by applying 

 a cord to the vertical cviiuderof wocxi, and attaching to the 

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

 sufficient weiirht to give successively to the machine dif- 

 ferent velocities. 



Having applied in this maimer a weight of 215 lbs., the 

 machine actjuired a motion, which after being reduced to 

 an uniform u'.otion, taking into account the atceleraiion of 

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

 gave 2-4 1 feet velocity; and having applied in the same 

 maimer a weight of ^220 lbs. the resulting uniform motion 

 gave a vclcjcity of 2'-)7 feet. 1 only mention these two 

 limits because they serve as a con)parisuo with what im- 

 T 4 mediately 



