66 TWENTY LESSONS ON POULTRY KEEPING 



with hens. There are now many types of incubators, hold- 

 ing from fifty eggs to several thousand eggs each. They are 

 heated by means of oil, coal, gas, or electricity. Hot air, or 

 sometimes hot water, is distributed through pipes which 

 pass through the upper part of the incubator, over the eggs. 

 The temperature is held at 103 degrees for the first week; 



Fig. 49. — A brood of chicks hatrlicd in an incubator. 



but is increased to 1 04 degrees the second week, and remains 

 stationary during the rest of the period of incubation. All 

 incubators are self regulating; that is, they have some 

 mechanical device for keeping the heat stationary. They 

 requii'o nothing on the part of the l)reeder save the keeping 

 up of the fire and the tTirning of the eggs. This must be 



