JOURNAL 



OP 



NATURAL PHILOSOPHY, CHEMISTRY, 



AND 



THE ARTS. 



APRIL, 1813. 



ARTICLE I. 



Experiments on the comparative Strength of Men and Horses, 

 applicable to the Movement of Machines. By M. 

 Schulze*. 



THOSE who have had occasion to construct machines in- Importance of 

 tended to be moved by men or animals, are sufficiently forc^oTmen* 1 

 aware how important it is to be acquainted with the quantity and animals as 

 of power that can be attributed to either of them, in order to fir st movers 

 estimate with accuracy the effect which it is proposed to obtain 

 from the machine. It is well known, that the arrangement of 

 the whole depends entirely on the ratio of the velocity of the 

 motive force to the resistance. This was the reason that long 

 ago induced experimentalists to take the trouble of determining 

 the strength as well as the velocity exerted by men and animals, 

 when they are made to move machinery j and the results they 

 obtained, which have been commonly made use of in comput- 

 ing the effect of machines, are, that men exert from twenty- 

 seven to thirty pounds, with a velocity of from one and a half 

 to two feet per second j and that a horse has about seven times 

 more strength than a man, with a velocity of from four to six 

 feet per second. 



These are the data which we have been obliged to use when- For aulas of 



* Memoirs of the Royal Academy of Sciences of Berlin for 1783. 

 Vol. XXXIV.— No. \5(), R These 



