THE PHYSIOLOGY OF MUSCULAR WORK 247 



Drill order without jacket. 



t Drill order with jacket. 



When the temperature of the air is high both by the dry and 

 wet bulbs the evaporation of sweat must be greatly increased in 

 order to cool the body. This is shown by a comparison of the 

 results obtained upon the same men, when they performed the 

 march on hot and cold days with the same clothing, equipment, 

 and load. 1 



The limits of the regulation of temperature are passed when 

 a man is obliged to work under unfavourable conditions of clothing 

 in a very hot and moist atmosphere ; the temperature of his body 

 rises to an abnormal height ; the production of heat exceeds the 

 loss, and a point is soon reached at which the metabolism becomes 

 extravagant ; more and more heat is produced, and heat-stroke (**) 

 is the result. This condition is seen in soldiers forced to march 

 carrying a load, and wearing unsuitable uniform and equipment 

 in a hot and humid atmosphere. 



1 Committee on Physiological Effects of Food, Training, and Clothing on the 

 Soldier, Second Report, 1908. 



