438 



THE REGULATION OF TEMPERATURE 



will be seen that between 3 and 4 o'clock in the morning body 

 temperature is at its lowest and between 3 and 4 o'clock in the 

 afternoon it is at its highest. This rhythm or periodicity is shown 

 by night workers as well as by those who live a normal average 

 life. After a very few days they become " acclimatised " to their 



nHBIRHinB 



I 2 3 4 5 6 7 8 9 10 H My; I Z34S67AS lo ii 'u, 



Fig. 98. — Cliart of the Daily Variation of Tempprature in tlie Jformal Human Subject, in 

 degrees Centigrade. The liours are niarlied from midniglit. (Kichet.) 



reversed " day," and thereafter have their peak temperature at 

 about 4 a.m. and their lowest temperature in the early afternoon. 

 Some people adapt very slowly. For instance, Benedict tells of a 

 night watchman who for seven years had been working during the 

 night and sleeping during the day, and had his maximum tempera- 

 ture about 4 o'clock in the afternoon when sound asleep and his 

 minimum about 4 o'clock in the morning when he was awake and 

 active. 



It is common knowledge that certain means may be taken to bring about 

 alterations in the body temperature : 



1. Muscular exercise causes heat. 



2. Want of muscular exercise is followed by cooling, e.g. cold has to be 

 guarded against during sleep. 



3. Heat or work causes sweating {'j-t'.) 



4. Heat produces lassitude. Compare the day's work of a man in Spain 

 with that of a man in Scotland. 



5. Still air has the same effect as that of heat on the feeling of lassitude. 

 The production of a movement of the air removes the tired feeling. 



6. A higher temperature can be endured in a Turkish than in a plunge 

 bath. Further, a hot dry climate is comfortably endured, while air at 

 the same temperature, but saturated with moisture, oppresses. 



7. Cold air does not chill one to the same extent as water at the same 



