File:American journal of physiology (1898) (14802193593).jpg

Identifier: americanjourn01ameruoft (find matches)
Title: American journal of physiology
Year: 1898 (1890s)
Authors: American Physiological Society (1887- ) American Physiological Society (1887- ). Abstracts of papers presented at the fall meeting American Physiological Society (1887- ). Proceedings
Subjects: Physiology Physiology
Publisher: (Bethesda, Md., etc.) American Physiological Society (etc.)
Contributing Library: Gerstein - University of Toronto
Digitizing Sponsor: University of Toronto

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, curves (i) and(3) in Fig. 3 are maximum static curves, the former recorded at the be-ginning, the latter at the end of the experiment. Curve (2) records The Measurement of Me^ital Activity. 289 the attempt to give a constant muscular innervation to the hand whileobserving with the eye the vibration of a seconds pendulum, andregistering each time the bulb reaches its maximum amplitude oneither side of the centre. It is at this moment of maximum ampli-tude that the electric connection is made in the pendulum, and thetime-marker records a second. If the tracings of the pen and thoseof the time-marker coincide, the observations are accurately recorded,showing good attention on the part of the observer. In Fig. 3 (2)the subject begins the mental work first, and then attempts the mus-cular, while the attention on the observation and registration iscontinued. The pneumatic pen of Mareys tambour registered each observa-tion. Two closed rubber tubes connected with the tambour by a(i) (2) (3)
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Figure 3. glass T-tube. The pneumatic pen recorded each time the rubbertube was pressed. The lever of the dynamometer, the time-marker,and the pen were arranged in the same vertical line at the beginningof each experiment. The second maximum static curve (Fig. 3, r3)) was traced tomake sure that the decrease in the preceding curve was not due tofatigue. Each curve was continued until the subject was consciousof the beginning of fatigue; a period of rest was then allowed.Every precaution was taken to eliminate fatigue. I have given in the following tables the results of the last tenexperiments with each hand, recorded in Fig. 3. The first experi-ments gave very irregular results, but after a little practice, I couldregister observations and pull the dynamometer at the same timemuch more accurately. In these tables, four constants, obtained by substituting ordinates,represent the force for the given time. In the formula for the con- P—pstant of attention, A ;= ~p~! fo^ the value of P,

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