FRESH AIR AND EFFICIENCY 289 



ing. Miiller and Noble found that the infection of 

 ^rabbits with " snuffles" (J3. bom septicus) is favoured 

 by chilling the animals after they had been exposed 

 to heat. Moreover, Leonard Hill has drawn attention 

 to the fact that a hot atmosphere, especially when the 

 humidity is high, leads to a congestion of the mucous 

 membrane of the nose, and that the increased secre- 

 tion of tissue lymph that results may provide an abnor- 

 mally favourable nidus for the development of germs 

 of disease. 



As to non-communicable diseases of the respiratory 

 organs, here again the depressing effects of foul air 

 and chilling reduce resistance to the effect upon the 

 lung's of anv sudden transition from the overheated 



O J 



moist atmosphere of a stuffy room to the outside air 

 of the colder months; bronchitis may result, and 

 attacks of frequent recurrence lead to lung conditions 

 which claim a heavy toll upon health and life. The 

 frequency with which such lung conditions are fol- 

 lowed by consumption is testimony to the fact that 

 they greatly favour the invasion of that disease. 



Thus the most essential requirement of our aerial 

 environment is that it should permit an easy loss of 

 heat from our bodies. The best indication of the 

 rate at which the skin surface can part with heat is 

 obtained by Leonard Hill's " Kata-thermometer ". 

 Essentially this instrument is a large-bulb spirit ther- 

 mometer, the bulb of which may be surrounded by a 

 muslin cover. This thermometer is first placed in hot 

 water (about 150^ F.), the excess of water is jerked off", 

 and the Kata-thermometer is then suspended in the 

 atmosphere, and the number of seconds taken in cool- 

 ing from 100 F. to 95 F. is noted. This indicates 

 the rate of cooling due to radiation, convection, and 

 evaporation. The rate of cooling at body temperature 

 is obtained by means of a factor for each instrument, 



(C948) 20 



