V. 



TEMPERATURE DETERMINATIONS 



149 



4. Applu'alions of Thermocouples 



Although ihermocouples can be used wherever Uquid-in-glass 

 thermometers are apphcable, they have the additional advantages of 

 small heat capacity and they can be read in situ by remote connection. 

 This is a particularly important consideration when it is desired to 

 measure the temperature of a patient in a fever cabinet or during 

 crj^otherapy (5). Under these circumstances, it is important that 

 the patient's temperature be recorded from minute to minute. 

 Fiu'thermore, thermocouples have more than 100 times the sensitivity 

 of a liquid-in-glass thermometer and are ten times as precise in the 

 hands of the ordinary observer. 



Particular applications of thermocouples to the measurement of 

 internal temperature may be described to demonstrate the great 

 flexibility of this method. Some of these are as follows: 



Rectal Thermometers. A simple type of rectal thermometer 

 was described by Hardy and Soderstrom (6) and consists of a single 

 thermocouple and a galvanometer. The cold junction is immersed 

 in a Thermos flask in warm water within 3°C. of body temperature. 



tSit^ 



Fig. 6. Circuit diagram of I'cctal thermomotcrs: (G) galvaiiomctpi-; (V) 

 vacuum Ijottle; (S) rotary switch. Lower rnjhf, construction of rectal tlier- 

 mometer: (T) rubber tubing; (L) latex coating; {J) thermal junction. After 

 Hardy, Duerschner, and Muschenheim (7). 



