386 



THE HUMAN MOTOR 



We see from these experiments that the expenditure of energy 

 per kilogrammetre varies by 100%, averaging about 8 small 

 calories. To account for these variations we must compute the 

 total work done by each subject (the resistant work being 52% of 

 the motive work) and the speed per second, and relate these to 

 the expenditure of energy. The curves in fig. 272 show that, 

 with very few exceptions, the output per kilogrammetre de- 

 creases with increase in the work done and the speed, increase of 

 load having an adverse effect on economy, as is shown in the 

 above table. Lastly, it will be seen that in the cases where the 

 subjects chose their own speeds, the differences observed show 

 the effects of personality in lifting or balancing the loads or in 

 adjusting them from time to time to suit their convenience. 



It is to be noted that the best result was 31716 kilogrammetres 

 per hour with a subject weighing 57 kg. and a load of 40 kg., 

 the speed being -12 metres per second. Hence the maximum 

 output of work per day of eight hours was : 



31716 x 8 = 253728 kilogrammetres. 



Hence, under the most favourable conditions, a daily output 

 of about 250,000 kilogrammetres can be attained, which gives 

 a dynamic expenditure of : 



250,000 X -008 = 2000 great calories. 



The experiment shows that, with heavy loads, of 50 or 60 kg., a 

 total daily output of 200,000 kilogrammetres cannot conveniently 

 be exceeded. 



