TYPES OF INCUBATORS 



237 



is kept for a sufficient period of time under certain conditions of 

 heat, ventilation, moisture, and position, it will be transformed 

 into a healthy fowl. 



Small incubators are heated by gas or kerosene, though most 

 of them use the latter. Gas burners require less attention and 

 are desirable in every way, but it is unfortunate that gas is not 



Fig. 149. — Double tray lamp incubator with capacity of from 200 to 400 eggs. 



available in all localities. Electricity is also used for heating 

 incubators, and has proved satisfactory, but it requires a totally 

 different method of radiation. The large incubators — those 

 which have a capacity of many thousands of eggs, popularly 

 known as mammoth machines, are mostly heated by a coal- 

 burning stove, though gas is used to some extent. 



The hot-air-heated machines are those in which fresh air is 



