too much heat. [ The tank being the source of heat 

 and there being no regulator in the egg chamber to 

 control that heater, even though you should be able 

 to keep the water in the tank at a stationary tempera- 

 ture forjthree weeks, the temperature of the egg 

 chamber will vary every time the temperature of the 

 room changes if it gets much warmer it will over- 

 heat the eggs ; if much colder, they will not have 

 enough heat. Overheating is the most dangerous] 

 Indeed, so delicate is the action, that this incuba- 

 tor has been known to run a week without varying 

 one degree of heat. [ When the temperature of the 

 room has not varied. ~\ There are no sleepless nights 

 connected with the use of this machine. [ We have 

 lost lots of sleep with them (and so have many 

 others).] This makes the most perfect regulator 

 ever invented, \water must be added to or drawn 

 from the tank according to changes of outside tem- 

 perature'} giving the operator absolute control not 

 only of the heat in the egg chamber, [as ' absolute" 

 as with no regulator at all\ but of any given egg 

 tray as well. As we depend upon the expansive 

 and contractile force of the water in the tank to 

 regulate the heat, [when we did, and the outside 

 temperature changed, we got left.] of course it 

 makes the principle which generates the superfluous 

 heat provide for its own escape. \_If the outside 

 temperature does not change] For instance, the 

 machine running at a given point, the water being 

 the source of heat, you cannot get any more heat 

 in the egg chamber unless you heat the water hot- 

 ter, and that is impossible unless you expand it, 

 95 



