388 ADVANCED PHYSIOLOGY 



temperature should not vary more than 2 from 68 F., and 

 the air should be neither too dry nor too moist. In buildings 

 heated with steam or hot water, special consideration should 

 be given the matter of humidity, as very dry air is irritating to 

 the lung membranes and is thus a menace to health. Moisture 

 should be provided in the form of steam, and the supply 

 regulated by an automatic humidometer. 



Furnishings. - Whatever the use of the building, its fur- 

 nishings must be such as may easily be kept clean. Fancy 

 wood furniture or iron desks are kept free from dust with great 

 difficulty. Carpets fastened down so that dirt cannot be 

 removed from under them are now little used; only such rugs 

 as can be easily and thoroughly cleaned should be considered 

 practical or desirable. Window hangings and upholstery 

 should also be selected primarily with reference to healthful- 

 ness. 



Cleaning of Buildings. In performing any cleaning the 

 one prime rule to insist upon is NO DUST, whatever the 

 method used. If the dust is removed and not scattered in 

 the process, the method is excellent. Cloths used in dusting 

 should be oiled to entangle and remove dust, not scatter it as 

 was the case with the old-fashioned feather duster. Prepara- 

 tions for entangling the dust and dirt should be scattered on 

 floors before sweeping them, and unless a vacuum cleaner is 

 used, rugs should be taken out of doors to be cleaned. 



In school-houses chalk dust should be wiped from black- 

 boards with a damp cloth or some other dust absorber. The 

 chalk trough below the board should be covered with wire 

 screening to keep hands and erasers from the dust. Slate 

 boards are cleaner than wooden ones, besides largely doing 

 away with the glare from reflected light. 



Disinfection of Rooms and their Contents. This pro- 

 cedure as a preventive against the spread of disease is of very 

 much less value than was once supposed. For instance, there 

 seems very little virtue in disinfection after cases of measles, 





