THERMO-REG ULA TORS 



163 



will be the deflection of the free end of the rod from the 

 right line; the lower the temperature the less of such deflec- 

 tion. If now the free tip of the rod be so connected with 

 the gas supply that with increase of temperature the supply 

 is decreased and with fall of temperature increased, it is 

 plain that by proper adjustment the gas opening can be 



FIG. 31 



Moitessier's gas-pressure regulator. 



brought to a point that will supply just the amount of gas 

 needed to maintain an approximately constant temperature. 

 The temperature of the incubator is to be regulated, 

 then, by the use of some such form of apparatus as those 

 just described. The regulator should be of sufficient deli- 

 cacy to prevent a fluctuation of more than 0.2 C. in the 

 temperature of the air within the chamber of the apparatus. 



