350 ARTIFICIAL BROODING 
On the small plant, with an average farm flock, raising from 
two hundred to perhaps a thousand chicks, the portable colony 
house, especially the gasoline brooder, is one of the best types 
to select. 
Long brooder houses may be grouped under four heads, accord- 
ing to the methods of brooding. One system has continuous or 
overhead pipes with hover boards above the pipes. Here the 
pipes usually extend along the top of each brooder compartment, 
these being from four to five feet in width. The hover consists 
of light boards hinged at the back, which can be lifted up to 
facilitate cleaning, the hover usually covering the entire end of 
the brooder pen. This was the first system extensively employed, 
but it is becoming obsolete because of better types. The brooder 
compartments are large and permit the handling of many chicks. 
There is not uniformity of temperature nor adequate control of 
it. It is especially adapted for use in the first’ week, but, owing 
to the great expense involved by having two houses, this type 
has given way to a system adapted to the entire brooding period. 
In this class of brooder house, the pipes are from six to eight 
inches above the brooder floor, the back of the hover compart- 
ments usually being ventilated by apertures covered with muslin. 
In front of the hover board is suspended a slotted burlap or felt 
curtain. 
The second brooding method, which is very popular and 
being more and more generally adopted, has at the back of each 
individual pen a specially constructed compartment with a cir- 
cular portable hover (Fig. 164). Here the heat is conveyed from 
a chamber below the brooder floor, through a galvanized metal 
pipe from four to six inches in diameter, and distributed into 
the hover just below the hover top. In this type of brooder it is 
essential that the hot-air chamber below be entirely isolated, 
so that no heat can escape and provide bottom heat, the objec- 
tion being that it causes weakness of legs and loss of vitality. 
The hot-air chamber is heated by means of hot-water pipes pass- 
ing’ through it from a central heating plant. The exact arrange- 
ment of the hover compartment itself admits of many variations. 
Some of original models provide: excellent advantages; among 
the best being ‘a damper in the metal pipe which makes possible 
the control of each compartment: 
The third method of equipping the long brooder house is 
to install individual brooders, either single or double units. 
