200 POULTRY PRODUCTION 



poured around the tank and past the flue carrying the hot 

 fumes of the lamp through the tank, as shown in Fig. 94. 



Lamp. — ^The essential parts of an incubator lamp are the 

 bowl and the burner. The bowl should be large enough to 

 hold sufficient oil to burn at least thirty hours, have a fortified 

 bottom and a gas escape. A fortified bottom is one that is 

 so braced to the top of the bowl that it is impossible to 

 spring it up and down, as may be done with the bottom of a 

 tin pan (see Fig. 100 at 18). The gas escape is usually simply 

 a hole punched in the oil cap. If the manufacturer fails to 

 put one there, the purchaser should do so (see Fig. 100 at 21). 



The necessity for these precautions arises from the fact 

 that the incubator lamp usually burns twenty-four hours a 

 day for several weeks during the season. This is a severe 

 test, and there are few lamps in which the oil does not 

 become somewhat warm. This causes the formation of gas. 

 There is no danger in this so long as it is not put under 

 pressure. A hole in the oil cap allows its gradual escape, 

 and avoids danger of explosion, provided it is not forced out 

 suddenly by the bellows action of the bottom of the bowl. 

 This difficulty is obviated by the fortified bottom. 



The essentials of a good burner are: (1) a sufficient size 

 to furnish the heat necessary during low extremes of tem- 

 perature, (2) a perfection of draft that does away with 

 any tendency to smoke when properly cared for, and (3) a 

 wick adjuster that works freely, allowing the flame to be 

 readily and easily controlled. 



Fuels. — The most common fuel used for hatching is 

 kerosene, and, unless otherwise specified, incubators are 

 furnished with oil heaters. In purchasing oil for this purpose 

 it pays to purchase the better grades. Cheap oil deposits 

 much more soot and is a source of danger. 



In the natural gas belt, gas is the most convenient and 

 often the cheapest fuel, providing a uniform pressure can be 

 secured. It may be used with the ordinary incubator by 

 replacing the lamp with a gas burner. 



As commercial currents become more constant and depend- 

 able, electricity will be used more as a source of heat for 

 hatching. Incubators designed specially for this purpose are 



