OUTLINES OF NATURAL PHILOSOPHY. 



and walk at the rate of two feet in a second, or a 

 mile and one-third an hour. 



A horse, according to DESAGULIERS, drawing a weight 

 out of a well, over a pulley, can raise 200 Ib. for 

 eight hours together, at the rate of two miles and 

 a half an hour. Supposing the horse, in this case, 

 to work to the greatest advantage, 



P = 300x9 =450, and c = 2.5 x 3 = 7.5 miles 

 4 



per hour. 



M. SCHULZE made experiments purposely to deter- 

 mine the values of P and c, in the above formula. 

 when applied to the working of men. He found by 

 trials made on the strength of twenty men, that, ta- 

 king a mean, P is to be estimated at 100 or 101 

 pounds avoirdupois, and c at 5.4 feet per second. 

 For the labour of a man, we may therefore suppose 



W = 101 (1 -- ~Y. Thus, if 

 5.4/ 



W = 30, v = 5.4 (1 T = 2.43 ; and in fact 



the common rate of a man's working may be near- 

 ly estimated at this amount. If, however, the for- 

 mula is correct, he does not work to the greatest ad- 



4 



vantage ; for then W would be - of P, or nearly 



9 



45 Ib., and v would be - of c, or 1.8 feet per se- 



<c9 



cond. 



M. SCHULZE; 



