EDWARD ELSWORTH. 237 



Various experiments, in hospitals, in tenements and 

 private dwellings, show that no ordinary system of ven- 

 tilation serves to materially diminish the number of dust 

 germs, but that absolute quiet does tend to free the air 

 almost entirely. Thus in the Boston City Hospital, at 

 midnight the number of living bacteria in 600 cubic 

 inches of air was found to vary from to 13, while 

 during the day time the number varied from 1 to 477. 

 The number was always largely increased by sweeping, 

 bed making, etc. 



In a carpeted living room in a 10th avenue tenement, 

 New York, 75 bacteria five minutes before sweeping were 

 increased immediately after sweeping to 2,700. 



It seems reasonably certain then, that whether we re- 

 main at home, or walk abroad, we are constantly exposed 

 to the danger of inhaling a certain quantity of dust, 

 which may, and pretty surely does, contain a varying 

 number of living organisms. It is certainly best to 

 avoid the danger as far as possible, and the co-operation 

 of government and individuals would reduce the danger 

 to a minimum. For the comfort of the race, our intelli- 

 gent investigators have determined certain facts, which 

 make it possible yet to enjoy life, in spite of the dis- 

 agreeable results which have been spread before us. In 

 the first place, only a small portion of the dust inhaled 

 goes into the lungs. Nature seems to have considered 

 the environment of man, and anticipated the dangers to 

 which he would, as an air-breathing animal, be exposed. 

 A considerable portion of the foreign matter inhaled 

 lodges and is retained on the moist surfaces of the nose, 

 the upper throat, the mouth, the windpipe and the 

 bronchial tubes. 



Of course the dust particles which are lodged in the 

 nose, upper throat or mouth, may be disposed of by 

 swallowing or ejection ; but how about that which has 

 found its way into the windpipe and bronchial tubes? 



193 



