12 
shock is given. The lower wavy line (/) is traced by a tuning 
fork vibrating 200 times a second, and serves to measure precisely 
the time occupied in each part of the contraction. It will be 
observed that after the stimulus has been applied, as indicated by 
the vertical line (s), there is an interval before the contraction 
commences as indicated by the line (c). This interval, termed 
latent period, when measured by the number of vibrations of the 
tuning fork between the lines S and C is found to be ,) of a 
second. During the latent period there is no apparent change in 
the muscle. 
In the lower the whole curve lasted about ,§, of a second, 
and the upper ji). 
I will now show a tracing of muscular shocks written by the 
leg of a frog which is beginning to be fatigued. In the lower 
part of the tracing the muscle was acting before fatigue had shown 
itself, and the contraction is shorter and more sudden than in the 
upper part of the field, where the tracing shows a contraction and 
elongation more slow and prolonged. 
A description of the instrument and its curves may be seen 
in Michael Foster, Halliburton, or other good work on physiology. 
I turn now to an instrument which will, I feel sure, interest 
you much more, as by it you can test your own muscle for fatigue, 
and record it by a tracing. The instrument has been named the 
Ergograph by Professor Mosso, its inventor. 
EXPLANATION 
One finger is placed in a leathern loop, the wrist and forearm 
being fixed as seen in the figure, the loop is fixed to the first 
phalynx of the middle finger, and to the loop is fastened a cord 
of catgut, running over a metal pulley, and carrying a weight of 
three or four kilograms. 
Now examine two og three tracings. The first two were 
taken by Professor Aducco and Dr. Maggiora, the third by Dr. 
Patrize. Notice the difference in the three. 
In the first there is a gradual diminution from the beginning, 
showing 46 contractions. 
In the second, fatigue came on much more rapidly, only the 
ten first contractions raising the weight to its required height, 
and the whole record extending to 37 contractions, or partial 
contractions. 
Vo. 3 shows an entirely different curve. In this there are 
41 contractions, all raising the weight nearly to the same height, 
and the fatigue came on quite suddenly, the finger refusing to 
respond any longer. These curves are quite natural, and true to 
experience. We find men and women who differ thus in the 
rapidity and manner in which fatigue comes on. There are some 
