SYSTEMS OF HEATING BROODER HOUSES 365 
infected, the best possible procedure is to isolate and slaughter 
the infected adults and thus prevent future outbreaks. Thorough 
disinfection of brooders and incubators will prevent the trans- 
mission of infection through future hatches. The organisms are 
easily destroyed by dilute acids; hence the feeding of sour milk 
to infected flocks for the first few days is advisable. Every 
poultryman hatching chicks should make all possible effort to un- 
derstand and prevent this disease, since it causes much loss. 
Hardening Process.—In order to prepare the chicks for re- 
moval to the range, after the second week, a hardening process 
should be begun. This consists in the gradual lowering of the 
temperature, with the idea of dispensing entirely with artificial 
heat in from three to six weeks, according to the weather. The 
best method is gradually to reduce the artificial heat until it can 
be entirely given up, then raise the hover a little at a time until 
it is safe to remove it and replace it with muslin-covered frames 
hung to the hover wall; these can be raised in front a little more 
each night until the chicks can do without them. It is imprac- 
ticable to take chicks from a warm brooder house and put them 
in a colony house unless they are gradually accustomed to the 
change. The idea should be to get them on the range as early 
as possible. After they are four weeks old, the sooner they are 
out on the ground in a cool atmosphere, and have large, well- 
ventilated quarters with free range and plenty of green feed, 
the faster they will grow, and the more hardy and vigorous they 
will be at maturity. 
Systems of Heating Brooder Houses.—There are two general 
systems of heating large brooder houses,—namely, hot water and 
steam. Hot water is the more generally used. It maintains a 
more uniform temperature with less variation either way, and 
the heat is retained much longer than by steam. The brooder 
house is a compact building requiring no complicated system of 
piping which would make steam necessary. 
The Heating Plant—In a long brooder house the boiler 
should be centrally located. It is poor policy to run the brooder 
pipes more than one hundred feet, as the loss of heat is great, 
the pipes become cool, and it is impossible to maintain an even 
temperature in all the hovers. With the hot-water system the 
heater should be located in a pit, in order to provide for the cir- 
culation and return of the cold water. Whatever type be selected, 
the heating plant should be installed by an expert. He must 
