24 POULTRY LABORATORY GUIDE 



Study carefully the self-regulating qualities 

 of the machine. They will consist of two es- 

 sential factors : — 



First, a sensitive thermostat. 



Second, a simple but accm-ate method of 

 transferring the energy of the thermostat to the 

 lamp. 



The self-regulating mechanism should admit 

 of easy and simple adjustment and should be so 

 constructed as not to lose its efficiency with age. 

 The successful operation of most thermostats is 

 based on the varying coefficient of expansion of 

 different metals. Note method of construction 

 so as to take advantage of this expansion. 



See that the entire regulating apparatus is 

 properly connected, and study the form and 

 function of each part. Adjust the thumb nut 

 so that the lever arm is balanced and the damper 

 suspended over the chimney. By turning the 

 thumb nut to the right the incubator is cooled, 

 and by turning it to the left the temperature is 

 raised. Why ? 



Trace the current of warm air through the 

 machine and out at the bottom. Notice methods 

 used to filter the air and stop it from flowing 

 rapidly. Why ? 



Remove the top of the incubator and note the 

 presence of double walls. What is the advantage ? 



