168 THE HUMAN MOTOR 



in the case of the muscles, because its terms cannot be separated, 

 but for inanimate motors, Weiss and Chauveau have given the 

 following example : 



Take an electric motor. A weight of 10 kilogrammes was lifted 

 in 1 second to a height of 2-50 centimetres. To effect this the 

 expenditure, as shown by experiment, was 17-50 watts t 1 ), 

 Ph = 10 X 0-025 = 0-250 kgm. = 2-45 watts. 



The expenditure needed to balance the weight was 8-50 watts, 

 this being D,. 



At the speed of 2-50 cm., the motor running light consumed 

 11 watts V, and R = 4-50 watts. Therefore : 



D rf = 8-50 -f 2-45 -f 114-50 = 17-45 watts, 

 which confirms the formula ( 2 ). 



Consider, in the same way, a hydraulic motor. The starting up 

 can be ignored. 



To lift a weight of 10 kilogrammes 10 centimetres, at a speed 

 of 0-001 m., the expenditure D d was 63-01. By calculating the 

 terms ~D e> Ph and V separately, a total of 62-66 was found. This 

 is a sufficient verification. ( 3 ) 



This calculation, as well as the other, concerns the expenditure 

 in positive or motor work only. Nothing accurate has been done 

 on the subject of negative or resistant work. If we simply 

 consider the work Ph as changing its sign we can write : 



(2) D', = D, Ph + V R. 



That is to say, not only is there no expenditure on account of 

 the work Ph, but there is even a regenerative effect. 



It is said that resistant work returns energy. This restitution 

 conforms to the law of equivalence ( 34). The muscle, in resist- 

 ing the production of work, destroys " vis viva," and dissipates 

 it as he-Jt, but that is not to say that, in resistant work one re- 

 cuperates useful energy. The variation of energy or the muscular 

 expenditure of muscle is expressed by : 



U=Q T, or D' rf = D, Ph+V R. 



Chauveau ( 4 ) and Hirn ( 5 ) were certain that calorific restitution 

 took place. A man works a treadmill in a calorimeter. His 

 expenditure, according to the oxygen consumed, reaches 257 

 Calories for a work of 68 Calories, and 193 Calories are registered 

 on the calorimeter. Therefore, in this motor work, 



(*) Remember that the watt (unit of power) equals about 102 kgm. 



( 2 ) A. Chauveau Journal de Physiologie, 1901. 



( 8 ) G. Weiss (Comptes Rendus Biologie, 1903, p. 426). 



( 4 ) A. Chauveau (Comptes Rendus Sciences, 1899, 2 sem., p. 249). 

 ( 6 ) A. Hirn Recherches sur I'Equiv. Mec. de la Chaleur. Colmar, 



1858. 



