110 
moist, the thorough, ventilation of living 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 cling 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." 1 
The regulation of air space alone can be of little 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 limits. 
The temperature at which the body may best be maintained under 
ordinary conditions has been found to range between 66 Q and 70° F., 
and the problem of ventilating convict camps resolves itself into one 
of keeping the temperature as nearly within these limits as possible 
during the winter months and in making inside conditions as nearly 
as possible like those out of doors in the summer months. This may 
best be accomplished 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 swelling 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. 
