MECHANICAL EFFICIENCY OF THE HUMAN BODY 
103 
consumed and the values of Q. Amar ° shows that if we are to consider the 
values of Q as correctly measured calorimetrically, the efficiency agrees 
reasonably well with that of Helmholtz, who computes it as 20 per cent. 
Although the classical experiment of Fick and Wislicenus b in their ascent 
of the Faulhorn has frequently been cited as an indication of the fact that the 
work was not done by the disintegration of protein, it is a matter of special 
interest in this connection to note that these authors computed their mechan- 
ical efficiency as equivalent to 50 per cent. 
Him c argues that the effective work represents one-fourth of the chemical 
action in the muscles, namely, an efficiency of 25 per cent. Joule d also con- 
tends that the efficiency is one-fourth, or 25 per cent, while in 1867 and 1868 
Paul Bert e computed that the values for English prisoners producing 260,000 
kilogrammeters per day would be 34 per cent for the net efficiency and 21 
per cent for the gross efficiency. 
In 1887 Hanriot and Richet/ working with their newly developed 
methods of studying the respiratory exchange and with a subject raising 
weights, assumed that muscular work is done by the consumption of glucose. 
As the net efficiency of their subject they found one-seventh, or 14.3 per cent, 
and concluded that the net efficiency of the body lies between 11.1 and 14.3 
per cent. 
In repeating some of Hirn's work on a wheel similar to the one used by 
him, Chauveau obtained results that were quite different. Computing the 
values from the amount of oxygen absorbed in excess of that absorbed during 
rest, the subject being without food in the stomach, Chauveau found a net 
efficiency averaging 14 per cent." Amar calls attention to the fact that there 
are marked differences in the calculated net efficiencies in two classes of 
experiments; thus, for going upstairs he found an efficiency as great as 
15 to 30 per cent, but when the work was done exclusively with the muscles 
of the arm he found but 3 to 5 per cent. The criticisms regarding the length 
Table 102. — Results of experiments made by LaulaniS with a constant amount of work. 
Oxygen 
Energv 
Duration of 
Effective 
increase 
required 
Net 
work. 
work. 
due to 
work. 
for effec- 
tive work. 
efficiency. 
hgm. 
liters. 
kgm. 
p. ct. 
5 minutes 
560 
1.333 
2,666 
21.0 
10 minutes 
1,206 
2.861 
5,722 
21.0 
15 minutes 
1,664 
3.900 
7,800 
21.3 
of the experiments and the methods used in carrying out his researches 
have already been cited. A mathematical treatment of Chauveau's results 
as to the efficiency under different conditions is admirably presented by 
Lefevre.* 
° Amar, loc. tit., p. 23. 
o Fick and Wislieeniis, Ann. dss sci. nat., 1868, 10, p. 273. 
c Hirn, Revue scientifique, 1887, 39, p. 673. 
d Joule, cited by Hanriot and Richet. Comptes rendus, 1887, 105. p. 76, who, in turn, cite from Fick, Mecha- 
nische Arbeit und Warmeentwicklung bei der Muskelthatigkeit, Leipsic, 1881, p. 231. 
« Bert, La machine humaine, 1867-68, 2, p. 50. Cited by Amar, he. tit., p. 24. 
/ Hanriot and Richet, Comptes rendus, 1887, 105, p. 76. 
Cited by Amar, loc. tit., p. 25. 
I* LefSvre (Chaleur animate et bioenergetique, Paris, 1911, p. 749). It should here be stated that a sharp dis- 
tinction as to the effect of the various factors on efficiency has rarely been recognized by writers, hence 
Letevre's abstract of Chauveau's work is of unusual interest. The variations in the percentage ascribed 
to the efficiencies by different writers is in large part explained by the lack of agreement on the basis 
of computation, a point that is clearly brought out by Lefe'vre. 
