436 



POPULAR SCIENCE MONTHLY. 



record follows the fluctuations of the heat record with as much pre- 

 cision as effect follows cause. The summer heat generally begins 

 about the 20th of June and continues with varying intensity until 

 the 15th of September. "Within that period we can select many 

 examples which strikingly illustrate the relations of temperature to 

 mortality. For example, the first heated term of the year before us 

 began on the 19th of June and lasted until the 26th of that month. 

 The two records are as follows : 



On the 2Sth of June a second heated term began, when the 

 temperature rose to 80°, and continued above that figure until July 

 5th, a period of eight days. The following is the record, including 

 the temperature in the sun: 



It will be noticed that during the last heated period there was a 

 more prolonged high temperature than during the first, and that the 

 mortality of the second was higher for the same temperature than 

 that of the first. These facts are in accord with the history of our 

 summer months. The range of temperature increases as the season 

 advances, and the rate of mortality rises, owing to the diminished 

 resisting power to the effects of high heat on the part of the people, 

 especially of the children, the aged, and those already enfeebled by 

 disease. 



In order to fully understand the influence of heat and its effects 

 upon the public health, we must first notice the conditions regulating 

 the temperature of the body in health and disease. 



The temperature of animals in a state of health is not a fixed 

 quantity, but has a limited range which depends upon internal and 



