ESSENTIAL FEATURES 109 
the experience of the poultryman caring for them. Under general 
conditions it is safest for the amateur or for the one with little 
experience not to crowd the birds too closely,—about one bird to 
every four and a half or five square feet of floor space. The expert 
who thoroughly understands the needs and methods of sanitation 
can successfully keep as high as one bird to every two and one-half 
- or three square feet of floor space. A desirable area for birds 
under close confinement during the winter months, when a heavy 
egg yield is desirable, is approximately four square feet per bird. 
5 
Fic. 67.—An efficient rear ventilator for summer use. It allows the air to enter the 
back of the house, and circulate between the sheathing and the roof, cooling the roosting 
quarters on summer nights. This is most valuable for shed-roofed houses that are covered 
with paper. Cornell University was the first Experiment Station to recommend back 
ventilation for the poultry house. 
Excessive Heat and Cold.—Protect the birds from cold, but do 
not keep them too hot. Birds will stand a great degree of cold; 
they do better in cold quiet air than in warmer drafty air. This 
latter condition is generally the starting point of colds which may 
develop into forms of roup, quickly putting the birds out of laying 
condition. The house should be so constructed that at any time 
the temperature will never get low enough to freeze the combs. 
This condition will vary with (1) the breed kept, (2) the vitality 
of the birds, (3) the scratching or other exercise, and (4) the amount 
of moisture in the house. 
Large-comb breeds must be given better protection and warmer 
