I9I0.] WORK ON NUTRITIVE PROCESSES. 159 



of total energy. This would give us an efficiency of not far from 

 14 per cent. On the other hand, another method of computing the 

 efficiency, and perhaps one that is fairer, is the method in which the 

 total resting metabolism is deducted from the total heat production 

 and we compare the work done with the increased amount of heat 

 required to do this work. Thus, in the first experiment out of 

 339 calories produced during work, 112 calories can reasonably be 

 assigned to the production necessary for maintenance while the 

 subject is sitting quietly reading in the calorimeter. Deducting the 

 112 from 339, we find that 227 calories of heat result in the pro- 

 duction of 49 calories of efficient work. On this basis, the efficiency 

 is 21.6 per cent. A similar calculation for the other subjects shows 

 the remarkable fact that there are but slight differences between 

 these men as regards their efficiency. In other words, for every 

 calorie of efficient muscular work done, there are about 5 calories 

 of extra heat produced. In the case of the enormous heat produc- 

 tion of Mr. Butler, we find that the differences in the two methods 

 of computation are not as noticeable for it makes but a small change 

 in the percentage whether we divide 112 multiplied by 100 by 619 

 or whether we divide 112 times 100 by 527. In the latter case, the 

 efficiency is 21.3 per cent., while in the first it is about 18 per cent. 

 Obviously, the greater the amount of work accomplished per hour, 

 the less the influence of deducting the resting metabolism. 



How does a man compare with an engine as regards efficiency? 

 I have no doubt but that some fault could be found with my 

 reasoning when attempting to compare a man with a machine but 

 the best steam engines of the present day do not average an effi- 

 ciency much greater than 14 per cent. Certain internal combus- 

 tion motors realize somewhat more. At any rate, we can say that 

 a man is a wonderfully efficient machine. 



The figures in Table IV shed a most interesting light on the 

 question of training. It has commonly been supposed that when 

 a person is trained, the muscles become more effective and conse- 

 quently there is a greater production of work for the same expendi- 

 ture. In these figures here we find that in the first place the two 

 men, A.L.L. and E.F.S., who were wholly untrained, and indeed 

 wholly unfamiliar with the bicycle, accomplished as much work as 



