288 REPORTS ON THE STATE OF SCIENCE.—1912,. 
form of electrical energy, and therefore not discoverable by reference 
to changes of temperature. 
It is impossible to proceed with a discussion of this point until 
the calorimeter has been converted in some measure into a ‘ respiration 
calorimeter ’ such that the carbonic-acid production within it may be 
tested at such short intervals of time as to furnish data for curves of 
oxidation processes, and this I am now attempting with the assistance 
of Dr. F. A. Duffield and hope to report upon at the end of another 
year. 
Leaving on one side, then, the special problem of the ‘ efficiency ’ 
during this initial period, I have used the data obtained after the first 
hour for an estimation of the maintained ‘ efficiency.’ 
Kstimations of the ‘ efficiency’ of man as a machine have been 
found to involve two main difficulties. In the first place, assuming 
that the actual external mechanical work performed at any time is 
accurately known, there are always present processes within the body 
both in parts such as the glands seemingly independent of the muscu- 
lature, and even within the musculature itself, by which internal 
mechanical work is being performed and necessarily accompanied by 
a transformation of energy and a proportional sum of oxidation 
processes; and these processes are not constant, but vary—partly in 
relation to the performance of external work and partly with no relation 
to this factor. The comparison frequently: made between measured 
work performance and so-called ‘ rest’ is then in reality a comparison 
between two imperfectly known quantities of work performance. 
Again, in the second place, it is a difficult matter to measure the 
mechanical work performed by movements of the body and its limbs, 
since work is done in those movements themselves apart from that 
which is done upon any mechanism to which they may be applied. 
This second difficulty I have investigated by experiments upon the 
cycle without any brake and against no more than the almost negligible 
resistance provided by the friction of its cogs and chain and bearings. 
Thus in separate experiments upon the ‘ brakeless ’ cycle subject E. J. B. 
(age forty-five, weight 55°8 kilos, height 168 cms.) gave the following 
results :— 
(1) 54 revolutions per minute, 107 kals per hour 
2) 64 ll 
( bed ” 2 9 
(3) 74 ” ” 144 ” 9 
(4) 85 ” 2? 174 ” 3? 
(5) 96 ” ” 233 ” ”? 
Such results admit of approximate expression in the form (k+2zR’), 
where k is a not too satisfactory constant and R is the revolution rate. 
Although k is not absolutely constant, it is, however, a relatively small 
quantity, and its variations complicate the results obtained at the lower 
revolution rates far more than at the higher. 
The thorough investigation of this question of the amount of 
mechanical work performed in mere movements promises to pave the 
way for a complete elimination of the second difficulty, but in the 
meantime it is more satisfactory to place in the forefront the results 
of experiments where the difficulty has been further avoided by the 
