General Experimental Conditions. 15 



aside from some mention of them in the succeeding pages under the 

 discussion of particular measurements, it must be assumed that they 

 tend in general to compensate each other. 



GENERAL EXPERIMENTAL CONDITIONS. 



At the time of the second series of observations, June 29 to July 4, 

 1914, the subject, having completed the year's work at the medical 

 school, was serving as intern in a neighboring hospital. His hours on 

 duty were from late afternoon until 1 a. m., and as he had considerable 

 freedom from work he regarded the period as vacation. His health was 

 excellent. On no day did he mention feeling the effects of a cold or a 

 headache. His habits were regular with respect to food and daily 

 routine. The last food before each experimental session was a hearty 

 meal taken 7 hours previously, from which coffee and tobacco were 

 excluded. This meal was taken between 12 h 30 m and 1 o'clock a. m., 

 that is, when the subject went off duty at the hospital. While the 

 food was varied as to kind, the amount was fairly constant. 



No alcohol was taken during the week, other than that given at the Labo- 

 ratory. The subject slept approximately 2 hours in the afternoon, be- 

 fore taking up his work at the hospital, and again from 1 until 8 a. m. 

 Immediately after dressing in the morning and without breakfast he 

 came to the Laboratory, and our experiment began at 8 h 30 m a. m. and 

 continued until l h 30 m p. m., a total period of 5 hours, as contrasted with 

 the 3-hour periods employed formerly. The longer periods were used 

 designedly, that the effect of alcohol might be followed further than in 

 the previous investigation. 



According to the statements of the subject, the longer periods were 

 not unsatisfactory. The variety and nature of the measurements were 

 such as to minimize the development of fatigue, and the periods were 

 not long enough to cause serious difficulty from excessive hunger. The 

 subject preferred to serve one long period rather than two short ones. 

 From the experimental standpoint longer sessions are more economical, 

 in that much less time is taken up in the preliminary adjustments, such 

 as weighing the subject and gathering and recording data relevant to 

 food and general conditions. The longer periods have the further 

 advantage of calling forth a more steady, even performance on the part 

 of the subject. 



In the former series the subject was working hard in regular course 

 in a medical school; it was not feasible for him or the other student 

 subjects to serve in the experiments on successive days, and an effort 

 was made to guard against any prominent weekly rhythm that might 

 exist by having all the experiments come on the same day of the week. 

 In the later experiments the need of extending the sessions over a 

 period of weeks to avoid any influence of a weekly rhythm seemed 

 less urgent than at the time of the previous experimenting, as the regular 



