190 THE HUMAN MOTOR 



to 23-8%. However, the average value of ^0-5% is small. 

 According to Frey, the muscles of the body would have to be 

 kept in a state of tension (static expenditure) to maintain 

 equilibrium on the apparatus for eight hours. Also it must be 

 added that the friction of the feet on the pedals developed a 

 quantity of heat which the calorimeter registered as dynamic 

 expenditure ; that the exactitude of the ergometer is not always 



Fig. 137. Bicycle Dynamometer (J. Amar). 



what one could desire, ( l ) and finally that a prolonged stay in the 

 calorimeter is unfavourable to the performance of a large amount 

 of work ( 105). Also the average effort 7-73 kg., was a high value. 



At least a hundred agricultural labourers, men used to an active 

 life, have ridden on the bicycle dynamometer, which will be de- 

 scribed in Technics ( 221). The arrangement of the apparatus 

 is shown in fig. 137. The experiments took place in the open air, 

 the average effort rarely attaining 400 grammes, and the duration 

 of the experiments not exceeding four hours for a daily amount 

 of work of about 55,600 kilogrammetres, made at a normal rhythm 

 of 90 to 92 strokes of the pedal per minute. As a rule, the sub- 

 jects worked two hours in the morning and two in the afternoon. 

 Under these favourable conditions 



R = 32-5%. 



(see also 290). The expenditure was estimated according to 

 the maintainence rations in repose and at work.( 2 ) 



(*) Atwater and Benedict (loc. cit., p. 34-35). 



( 2 ) Jules Amar (Le Rendement de la Machine Huntaine, p. 60. Jules 

 Lefdvre, in his Traite de Bio inerg Clique, gave an erroneous interpretation 

 of our calculation of the yield ; this was pointed out in C. R. Sciences of 

 June, 1911. 





