110 BULLETIlSr 414, TJ. S. DEPAETMENT OF AGEICULTUEE. 



moist, the thorough ventilation of Uving quarters will prevent indoor 

 conditions from being many times worse. 



From recent experimental evidence it appears reasonable to con- 

 clude that the bad effects of stale air are due to the heat and moisture 

 which it contains and permits to cHng around the body, forming what 

 has been called an "aerial blanket." ''The breaking up of this zone 

 of concentrated discomfort by circulation of the air is a most impor- 

 tant factor in good ventilation."^ 



The regidation of air space alone can be of httle value. No mat- 

 ter how large the space, the atmosphere may become stagnant, 

 moist, and overheated, and however small the space, the tempera- 

 ture and humidity may be kept within healthful hmits. 



The temperature at which the body may best be maintained under 

 ordinary conditions has been found to range between 66° and 70° F., 

 and the problem of ventilating convict camps resolves itself into one 

 of keeping the temperature as nearly within these hmits as possible 

 during the winter months and in making inside conditions as nearly 

 as possible hke those out of doors in the simimer months. This may 

 best be accomphshed by making several small inlets for fresh, cool 

 air in both sides of the building at the level of the floor and providing 

 outlets for the heated air in the roof, preferably along the ridge. 

 Ventilating openings should always be screened. The size and num- 

 ber of ventilating openings should depend upon the size and shape of 

 the room, and no general statement will apply under all circumstances. 

 In a large apartment it is usually better to provide a number of small 

 openings for the incoming air rather than one large one, and the same 

 is true of outlet openings. 



An excellent type of structure for summer use is that in which 

 the sides and one or both ends are open and protected by screens for 

 a space of 3 or 4 feet in width all the way around . 



Tents and other structures whose sides are inclosed only with canvas 

 curtains receive a considerable amount of air which passes through 

 the pores of the canvas, but when the temperature of the inside and 

 outside air is about the same, and in wet weather when the pores 

 become closed by the swelhng of the canvas, the ventilation may be 

 bad, and openings should always be provided at the ridge. Types 

 of poorly ventilated quarters are shown in Plate V, figures 1 and 2. 



Heating. 



Almost all convict camps use wood-burning stoves for heating 

 purposes and find the method generally satisfactory. The stoves 

 are placed as near as practicable to the center of the room, or distrib- 

 uted along the aisles when more than one is required. At one camp 

 of a somewhat permanent character a complete hot-water heating 



I Winslow, C. E. A. 



