238 COMMERCIAL POULTRY RAISING 



taken in at the lamp, heated as it passes around the drum, which 

 corresponds to the chimney of a lamp, and passed through the 

 egg chamber by means of a diaphragm in the ceiling of the ma- 

 chine, and then out through variously arranged outlets. See 

 Fig. 150. In some machines the heated air only passes over the 



J N 



w 



^California Experiment Station) 



Fig. 150. — Cross-section of a hot-air incubator, showing method of regu- 

 lating the temperature and ventilation, a, Counterpoise weight; b, regulator 

 arm; c, connecting rod; d, thumb-screw; e, pivot casting; /, heater disc; g, 

 cotton batting filling between inside and outside cases; h, thermostat; t, 

 egg chamber; j, moisture pan; k, nursery; m, bottom ventilator; n, insula- 

 tion in bottom of incubator; p, outlet to discharge air from egg chamber into 

 false bottom beneath moisture pan; r, fresh air intake; s, outlet for escape of 

 lamp fumes. 



radiator above the egg trays, and never actually enters the egg 

 chambers. 



Hot-water machines are heated by tanks or a system of pipes 

 above the egg trays. In both types the heat is supplied with a 

 regulator which, acting upon a valve or damper, controls the 

 admission of heat to the egg chamber. Such a device is called 

 the thermostat. 



Moisture. — Whether moisture should or should not be sup- 



