DUST AND ITS DANGERS. 8 1 



informed of the danger of the practice, will be 

 apt to convey some of the material discharged 

 from the lungs to situations in which without 

 care and vigilance on the part of those who 

 afterwards clean the rooms, it may form a part 

 of inhalable dust. 



Many of the theatres are probably the most 

 likely places of any which we know frequented 

 by healthy persons in large cities for the inha- 

 lation of disease germs of one kind or another, 

 especially the germ of tuberculosis. The ven- 

 tilation is usually wholly inadequate even for 

 the purpose of carrying off the vitiated air of 

 respiration or exhalation, and is of almost no 

 use in freeing the air of dust. Close walled 

 they are apt to be, so that large volumes of 

 out-door air rarely or never sweep through 

 them ; sunlight is usually excluded ; carpeted ; 

 the chairs upholstered in plush ; visited by 

 large numbers of all kinds of people, who, in 

 the long sittings, cleanse their shoes on the 

 carpets, if they do not add to this their sali- 

 vary contributions. The floating particles ac- 

 cumulate in theatres in enormous quantities, 

 in such quantities, indeed, that the tell-tale elec- 



