Page:The American Journal of Psychology Volume 1.djvu/68

 62

LOMBARD I

Fig.

14.

April 1887

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coming less vigorous and attributed the change to- the fact that the weather was becoming warmer. The first warm spring days give most men a feeling of lassitude, and the subject knew that he was no exception to the rule. One's sensations are unreliable data, unless corroborated by more substantial evi- dence, and it seemed worth while to compare the recorded variations of the knee-jerk with the varia- tions of the temperature during the two weeks. The U. S. A. weather observations were accordingly

consulted, and it was- found that, in gen- eral, as the temper- ature increased the knee-jerk became less. The correspondence was not so close, how- ever, but that it was evident that other in- fluences were at work, and it occurred to the writer that the barom- etric changes of the atmosphere might be of importance in this connection. How greatly the extent of the knee-jerk is in- fluenced by thermom- etric and barometric changes can be best understood by study of Fig. 14.

Explanation. — At the head of the chart is written the dates on which the experiments were made, and at the left side the

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