NATURAL AND ARTIFICIAL INCUBATION 



81 



have it so arranged as not to subject it to any great varia- 

 tions in temperature and so that it will be well ventilated 

 with fresh pure air. Muslin screens placed in the window 

 frames provide good ventilation without draft and at the 

 same time keep the sun from shining on the machines. Good 

 results are secured in an incubator cellar as well as in 

 incubator rooms which are entirely above the ground level. 

 An incubator cellar, however, is more commonly used and 

 usually better hatches can be secured. Incubators may be 

 operated in buildings with single walls, especially in sections 

 which have a mild climate. 

 A building with a wall that 

 is well insulated, however, is 

 preferable. 



OPERATION OF THE 

 INCUBATOR 



Before beginning the ac- 

 tual operation of an incuba- 

 tor, attention should be 

 directed to a thorough under- 

 standing of two very impor- 

 tant parts of the machine, 

 namely, the thermostat and 

 the thermometer. 



The thermostat. The part of the incubator which con- 

 trols the regulation of the heat is called the thermostat. 

 This instrument acts on the principle of expansion and con- 

 traction caused by changes in temperature. It is fastened 

 in the egg chamber and connected by a rod to a bar. 

 This bar extends across the incubator to the lamp and 

 has suspended from its other end a metal disk which covers 

 the opening over the heater. As the temperature of the 

 incubator increases the thermostat expands, which by means 

 of the connecting rod raises the disk over the lamp and re- 



Figure 81, — A hot-air incubator 

 showing the bar on the top of the 

 machine that is controlled by the 

 thermostat 



