HYGIENE AND SANITATION 



169 



present in the air. The test is as follows : The sense of smell is 

 immediately recorded upon entering a building from the out- 

 side. If no sensible difference in smell can be determined, 



C^ 



7/1^ 



^^ 



'^ 



J 



Fio. 59. — If a house be constructed as indicated the vitiated air would rise 

 at the highest point in the house, which is at c, and unless provided with a 

 ventilator would stagnate there. With the ventilator the air enters the 

 house at a (an open front) , passes backward over the roosts at 6, and takes 

 an upward course and out the ventilator at e. 



Fig. 60. — The half monitor is a good building from a hygienic standpoint. 

 The air enters the open front at a and passes backward to the roosts at d, 

 and the ^-itiated air being lighter rises and passes out at e, and some cur- 

 rents, taking the course indicated by /, pass out the upper part of the open 

 front at a. 



the inside air smelling as fresh as that outside, the amount of 

 organic matter is at its lowest point, and such air is given on 

 analyses 0.6 per thousand or per cent, carbonic acid; that is. 



