40 TEMPERATURE FLUCTUATIONS IN THE HUMAN BODY. 



From the very sharp gradient, it may be easily inferred that the surface 

 temperatures of the body, or those slightly below the surface, are liable to the 

 greatest errors in determination, and consequently, as ordinarily measured, 

 they can have but little physiological significance. 



SELECTION OF LOCALITIES FOR SIMULTANEOUS MEASUREMENT 

 OF FLUCTUATIONS IN BODY-TEMPERATURE. 



NATURAL CAVITIES. 



The rectum and the vagina used alone are not especially suitable for study- 

 ing the constancy or the lack of constancy of temperature fluctuations in 

 different parts of the body, since these two cavities are side by side. Unfortu- 

 nately no other cavity presents such ideal conditions for the study of fluctua- 

 tions in body-temperature as do these, the only other openings which could be 

 used being the mouth and the oesophagus. While it has long been the custom 

 of physicians and physiologists to take temperatures in the mouth, certain 

 grave objections have been raised to the use of this locality, and it is obvious 

 that a more careful study of buccal temperature should be made before rely- 

 ing upon this cavity for exact temperature measurements. Accordingly, 

 a considerable amount of experimenting was done in connection with this 

 research to test the reliability of temperatures taken in the mouth. 



TEMPERATURE MEASUREMENTS IN THE MOUTH. 



A variety of methods were used for taking mouth temperatures, but even 

 when extreme care was observed, the results were unsatisfactory. The experi- 

 ment was tried, for instance, of inserting a thermal junction beneath the 

 tongue and recording the temperature until it became constant; the thermal 

 junction was then withdrawn and immediately replaced by a carefully cali- 

 brated clinical thermometer 1 which was allowed to remain in position for 5 

 minutes. The temperatures indicated by the two measurements were not 

 identical, the thermal junction giving results 0.2 to 0.4 F. lower. Again, the 

 mercurial thermometer and the thermal junction were fastened together and 

 inserted beneath the tongue for a period of possibly 20 minutes, the thermal 

 junction being read at regular intervals until a maximum was reached, this 

 requiring some 15 minutes. When the maximal reading was compared with 

 the clinical thermometer reading it was found to be 0.1 to 0.3 F. lower than 

 the latter. 



This continual disagreement led to a doubt as to the wisdom of using this 

 locality for taking temperature records, and of the clinical thermometer as a 

 standard. As a further test, the experiment was then tried of tying two 

 clinical thermometers together, inserting them in the mouth, and removing 

 them at the end of 5 minutes to take the records. After the thermometers 

 had been shaken down, they were replaced in the mouth and further 5-minute 



'Inasmuch as the Fahrenheit degree is employed in graduating practically all of the 

 mercurial clinical thermometers used in this country, this unit is made the basis of the 

 discussion of buccal temperatures, although in all other sections of the report the centigrade 

 scale is regularly used. 



