YIELD OF THE HUMAN MACHINE 



191 



134. (b) Use of a Lifting Gear. The subject worked a kind of 

 quarrier's winch, vide fig. 216, when enclosed in a calorimetric 

 chamber, his expenditure being calculated by the oxygen con- 

 sumed. At the commencement of study of human thermo 

 dynamics, Hirn ( l ) made some experiments in which the calori- 

 metric measurements are probably wrong, but there remain those 

 relative to the oxygen, the respiratory quotient being 0-99 since 

 the subjects were fed on feculents. Taking 5-05 Calories per litre 

 of oxygen, the expenditure can be calculated fairly exactly. 

 Chauveau ( 2 ) corrected Hirn's method later. Here, first of all, 

 are the latter's figures : 



The two last subjects were well developed and robust ; the 

 first and third (women) were young people of 18 years old ; 

 Number II. was Hirn himself. It will be seen that, in this case, 

 the yield has dropped to about 17-50%. Atwater and Bene- 

 dict obtained equally low results in experimenting on chemists 

 and other men belonging to the laboratory. 



Hirn made his experiments last from 41 to 90 minutes, in a 

 calorimeter maintained at temperatures ranging from 17 to 23C. 



Chauveau, in his trials of one hour, found that the net yield 

 rose to 264% ( 114) ; but for durations of eight to ten minutes 

 he found an average of 20-2% only. 



Thus: 



50-47 65-09 60-74 71-06 

 245 277 292 380 



Work (Calories) ... 35-52 

 (Calories) 206-50 



R 



17-50% 20-60% 23-50% 20-80% 18-70% 



(*) Ad. Him, Recherches sur I'Equiv. (loc. cit.) ; Revue Scientifique, 1887. 

 j) A. Chauveau (Comptes Rendus Sciences, 1901, first half year, p. 194). 



