The Necessity of Pure Air for Health. 269 



duced from the impurity of the air in the faftories, but 

 these do not need remark here. Finally the impure air 

 when it does not produce disease reduces the general 

 vigour of the body and renders it more liable to diseases 

 of all kinds and to the more fatal type of each disease. 

 Air is subject to the laws of gases, so inequalities of 

 temperature cause movement, the hot air ascending and 

 cool air coming in from without, but here where the air in 

 bedrooms is about the same temperature as outside, there 

 can be no great change from this cause, and further this 

 change does not affe6t the organic matter muchj so other 

 means for good ventilation must in the colony be used ; 

 and the steady blowing winds help us here, for all 

 that is necessary is to provide a good big inlet 

 in proportion to the number sleeping in the room 

 on the windward side and an exit on the other, and 

 the objeft is achieved. And no better examples of 

 this method of ventilation can be found in this colony 

 than in the institutions in New Amsterdam. Here in 

 the Asylum Dr. Grieve banished phthisis as a disease 

 of the institution which he found prevailing on taking 

 charge of it, and this was done by a proper adjustment 

 of square and cubic feet per bed with standing jalousies 

 and openings under the eaves to admit of 3,000 cubic 

 feet of air per bed per hour being supplied in all weather. 

 In the Hospital a similar plan is pursued with benefit, and 

 in the Alms House recently the upper sashes of all the 

 windows have been removed, and since then there have 

 been fewer deaths and no increase in the sickness rate. 

 Here no complicated system for ventilation is necessary, 

 as at home, where not many years ago thousands of 

 pounds were spent in an elaborate scheme for ventilating 



LL2 



