THE CALORIMETER. 49 



experiments with the respiration calorimeter. It was soon found that the 

 ordinary mercurial clinical thermometer was not best suited for the most 

 accurate observations of body-temperature and a special type of thermome- 

 ter employing the electrical-resistance method was used. In many of the 

 experiments, however, it is impracticable with new subjects to complicate 

 the experiment by asking them to insert the electrical rectal thermometer, 

 and hence we have been obliged to resort to the usual clinical thermometer 

 with temperatures taken in the mouth, although in a few instances they 

 have been taken in the axilla and the rectum. For the best results the 

 electrical rectal thermometer is used. This apparatus permits a continuous 

 measurement of body temperature, deep in the rectum, unknown to the 

 subject and for an indefinite period of time, it being necessary to remove 

 the thermometer only for defecation. 



As a result of these observations it was soon found that the body tem- 

 perature was not constant from hour to hour, but fluctuated considerably 

 and underwent more or less regular rhythm with the minimum between 3 

 and 5 o'clock in the morning and the maximum about 5 o'clock in the 

 afternoon. In a number of experiments where the mercurial thermometer 

 was used under the tongue and observations thus taken compared with 

 records with the resistance thermometer, it was found that with careful 

 manipulation and avoiding muscular activity, mouth breathing, and the 

 drinking of hot or cold liquid, a fairly uniform agreement between the two 

 could be obtained. Such comparisons made on laboratory assistants can 

 not be duplicated with the ordinary subject. 



It is assumed that fluctuations in temperature measured by the rectal 

 thermometer likewise hold true for the average temperature of the whole 

 body, but evidence on this point is unfortunately not as complete as is 

 desirable. In an earlier report of investigations of this nature, a few experi- 

 ments on comparison of measurements of resistance thermometer deep in 

 the rectum and in a well-closed axilla showed a distinct tendency for the 

 curves to continue parallel. A research is very much needed at present on 

 a topographical distribution of body temperature, and particularly on the 

 course of the fluctuations in different parts of the body. A series of electric- 

 resistance thermometers placed at different points in the colon, at different 

 points in a stomach tube, in the well-closed axilla, possibly attached to the 

 surface of the body, and in women in the vagina, should give a very accurate 

 picture of the distribution of the body-temperature and likewise indicate 

 the proportionality of the fluctuations in different parts of the body. Until 

 such a research is completed, however, it is necessary to assume that 

 fluctuations in body-temperature as measured by the electric rectal ther- 

 mometer are a true measure of the average body-temperature of the whole 

 body. Indeed it is upon this assumption that it is necessary for us to make 

 corrections for heat lost from or stored in the body. It is our custom, 



