MECHANICS. Ill 



trap. vui. p. 244, the same that is given in the last 

 article. He appears to have done so merely on ac- 

 count of the analogy thus preserved between the 

 action of animals and of fluids. M. SCHULZE, of 

 the Academy of Berlin, has since proved by direct 

 experiments, that this formula is nearer the truth 

 than the other. Mem. de TAcad. de Berlin,, 1783, 

 p. 333, &c. 



182. The effect of animal force, then, or the 

 quantity of work done in a given time, will be 



t>Y 

 proportional to W v, or t6 P v (1 -) , and will 



c 4P 



be a maximum when v =: , and W iz ~~ , that 



is, when the animal moves with the one-third of 

 the speed with which it is able only to move itself, 

 and is loaded with four-ninths of the greatest load 

 it is able to put in motion. 



The quantities P and c can only be determined by ex- 

 perience, and as they must differ for different indi- 

 viduals, an average estimation of them is all that 

 can be obtained. Even that average is but imper- 

 fectly known ; EULER supposes, that for the work 

 of men, P may be taken 60 Ib. and c = 6 feet 

 per second, or a little more than four miles an 

 hour. 



A man, according to this estimate, when working to 

 the greatest advantage, should carry a load of 27 Ib., 



and 



