180 THE HUMAN MOTOR 



amount of work done : 



(65 + 53) h = (65 + ^ 55>35 = 123,232 kilogrammetres. 

 5o 



123 232 



This maximum work done with a load is about z-r rz- or 



65%, practically two-thirds, of the work done without a load. 

 Coulomb determined the maximum amount of work in a great 

 number of trades, by experiment and calculation,^) as will be 

 detailed later. 



To obtain useful results by the above method it is necessary 

 Coulomb said so clearly to take a strong workman working 

 on piecework. It may be added that it is advisable to multiply 

 the experiments and only to submit incontestable average 

 values to calculation. Those of Coulomb, alwavs taken from 

 single observations, and sometimes bonowed from none too 

 reliable observers, are not sufficiently reliable, in spite of the in- 

 disputable authority of that celebrated natural philosopher. 



At the same time, his is the honour of having introduced into 

 science this kind of research, which others, at a later date, such 

 as Frederick Taylo A , Gilbreth, etc., applied to industrial problems. 

 (See 303). 



123. Another method, first employed by De la Hire ( 2 ) in 

 1702, and developed by Coriolis ( 3 ) in 1829, is similar to that 

 which hydraulic engineers use to calculate the work of a current 

 of water acting on the paddles of a water wheel. These scientists 

 assumed that a fluid circulated in the muscles with a speed u. A 

 man of a weight Q does a maximum amount of work unloaded 

 at a speed V. If he is loaded with a weight P he will work at a 

 speed v. Assuming that the efforts are proportional to the 

 squares of the speeds, calculation will lead to the following results : 



1. The man produces a maximum amount of work in lifting a 

 load scarcely equal to f of the weight of his body. ( 4 ) 



2. The speed is, in these conditions 48% of his speed without a 

 load. 



The calculation is very simple, the proportion of the efforts 

 to the squares of the speeds giving : 



' 



( x ) C. A. Coulomb (1736-1806), Memoire sur la Force des Hommes, written 

 in 1786, on his return from a voyage to Martinique, but published in 1799 in 

 the Memoires de I'Institut., vol. ii., and in Theorie des Machines (Bachelier, 

 1821). 



( 2 ) De la Hire (Mm. A cad. Roy. Sciences, 1702). 



( 8 ) Coriolis : Du Calcul de VEffet des Machines, pp. 278-9, 1844 (2nd edn.). 



( 4 ) Coulomb's method gave f, or a little more than f for ascending 

 with loads. 



