[Let the outside temperature rise 20, 40 or 50 

 jj/<? wz// yfodf w0re heat than you want in the egg 

 chamber, and you will not wait for the water to ex- 

 pand if you wish to save the eggs, but will draw off 

 some hot and add some cold water to the tank. ] and as 

 the expansive force of one- fourth of a degree will cut 

 the lights entirely off, it makes it simply impossible 

 to overheat the machine or eggs. [It is possible at 

 times to blow out the lamps entirely and still over- 

 heat a hot water incubator , especially during the 

 last week, when the animal heat in the eggs is in- 

 creasing rapidly. ~\ Manipulating the lamps does 

 not affect the heat in the egg chamber at all. 

 [Rats !] All the operator has to do is to see that 

 he has enough of flame, and the regulator will 

 take care that he does not get too much. [Some 

 operators depend entirely upon manipulating the 

 lamps, and dispense with the regulator. If the tem- 

 perature of the room would not change, the regula- 

 tor might control the temperature of egg chamber ; 

 but if the temperature of the room is kept stationary, 

 why not hatch in the room instead of buying an in- 

 cubator f\ We use two lamps on our largest ma- 

 chines, though usually one is all sufficient to furnish 

 all the heat required. We call one our safety 

 lamp ; for instance, should the operator forget to 

 fill one lamp, and the light should go out, the 

 water cools contracts the float is lowered, the 

 heat is turned on in full force on the other lamp 

 and the heat is not changed at all in the egg cham- 

 ber. Suppose he forgets to attach the extinguisher 

 to one lamp, and double heat is turned on ; the 

 96 



