Chemistry and Physics. 147 
10. On the law of een: in the work done by men or anim 
—The Rev. Dr. Haughton, of Trinity College, Dublin, has raat 
brought to a ater bat a series of papers on Animal Mechanics 
published in the Proceedings of the Royal Society. The ninth of 
these papers was oe the Croonian Lecture for the present 
year, and the t paper closes the series. 
The most Paek se subject involved in these papers is the 
greatest usefulness to the science of me has upon which i 
depends, how to one ys to the greatest eee advantage, o 
force of animal a 
r. Haughton believe that he has found the proper form of 
this function, by means of experiments, and sums it Bu in what he 
calls the Law of Fatigue, which he thus expresses : 
é product of the total work done sis the rate of if work is con- 
stant, at the time when fatigue stops the w 
If W denote the total work done, the tite of fatigue gives us— 
dw 
ible ry = const. 
Ww? 
or — = 
7 = const. (1) 
The experiments made by Dr. Haughton from 1875 to 1880 
consisted chiefly in lifting or holding various weights by means 
the arms; the law of fatigue giving, in each case, an appropri- 
ate equation, with which the results of the experiments were 
compared. en the experiments consisted in raising weights 
on the outstretched — at fixed rates, the law of fatigue gave ~ 
the ineiae | expressi 
ge +a)nr= (2) 
where w, n, are the weight held in the hand, and the eco - 
times it is lifte , A is a constant to be determined by experi 
and @ another constant aaaedine + on the weight of the limb and 
its appendages. 
The equation (2) represents a cubical hyperbo 
The useful work done is delerers: by the cation — 
0 7 = wether 
“hae Fh): (3) 
This denotes a cuspidal cubic, and the wseful work is a maximum, 
