82 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 60 



The efficiency of workers in mills, mines, tunnels, stoke holes, etc., 

 is vastly increased by the provision of a sufficient draught of air, 

 so as to prevent over-taxing- of the heat-regulating- mechanism. 

 600,000 cubic feet of outside air are pumped every minute into the 

 engine rooms of the Lusitania, and the temperature thus lowered 

 from 150 to 70 ° and the men feel no draught and are comfortable. 

 The human skin, if exposed to a tropical sun, is warmed 3 to 4 

 C. above the normal surface temperature ; a rise of body temperature 

 is alone prevented by movement of the air and by evaporation of 

 sweat. If the air is still and evaporation is checked by a high wet- 

 bulb temperature, or by deficient action of the sweat glands, the 

 body temperature rises and danger of heat-stroke arises. Rabbits, 

 monkeys, and dogs evaporate water from the lungs and mouth, and 

 their capacity to stand exposure to a hot sun is limited. Monkeys 

 exposed to sunshine in Manila died within 70 to 80 minutes, while 

 the protection afforded by an umbrella saved them from all harm. 

 A tracheotomized dog died when exposed to the sun, for the heat 

 regulation was inhibited and the body temperature rose to febrile 

 heights. 1 



The experiments of J. Haldane, and others made by us on the wear- 

 ers of the Fleuss dress, show that a very rapid pulse, low blood-pres- 

 sure, rapid respiration, rise of rectal temperature, f aintness, vomiting, 

 and collapse result from prolonged exposure to a wet-bulb temper- 

 ature of 95 F. The same symptoms result from a few minutes expos- 

 ure to a hot bath ( 1 io° F.) if all the body is immersed except the face. 2 

 The skin is greatly flushed and the skin temperature raised. The rec- 

 tal temperature may reach 103 ° F., the pulse rate rise to 150, the 

 blood-pressure sink to 80, the respiratory rate rise to 30, and pulmo- 

 nary ventilation to 50 liters. The symptoms are immediately relieved 

 by a cold douche, with the exception of the rectal temperature. It is 

 the circulation which fails, and this is immediately restored by the 

 constriction of the skin. The rapid and dangerous sequence of 

 events which follow exposure to these high temperatures points con- 

 clusively to the true cause of the discomfort which people feel in 

 crowded rooms. Those who have a feeble circulation and deficient 

 heat-regulating mechanism may collapse at a wet-bulb temperature 

 io° or 15 F. below that which affects a strong man, while almost 

 all may feel discomfort and suffer fatigue. 



Flugge has found in German high schools temperatures as high 

 as 23 ° to 26 ° C. (73.5 to 79 F.). He made observations on 29 



1 II. Aron, B. M. J., 191 1, II, p. 777. 



2 Hill and Flack, Proc. Physiol. Soc. ; Journ. of Physiol., Vol. 38, 1909. 



