194 



POULTRY PRODUCTION 



Incubator Sizes. — Most farm incubators range in capacity 

 from fifty eggs to four hundred and fifty. The sizes ranging 

 between one hundred and fifty and two hundred egg capacity 

 have trays that may be conveniently handled and are not 

 so large as to have great differences in temperature between 

 opposite sides or corners of the egg chamber. 



Where the capacity runs much above three hundred there 

 is likely to be a difference in temperature of several degrees 

 between opposite corners, and the trays are heavy and 

 awkward for the ordinary person to handle, when they 

 are full of eggs. 



Fig. 96 



Mammoth incubator. (Courtesy of Kansas Experiment Station.) 



The so-called mammoth incubators, with egg capacities 

 running into the thousands, are made up of a larger or smaller 

 number of ordinary sized incubator units built together. 

 Aside from the fact that there is a central heating system, 

 each unit is independent of every other unit, having its own 

 regulator, nursery, and trays. It is entirely possible to be 

 bringing off a hatch in one compartment and just starting 

 another one in the next one. 



The Regulating Device. — ^The regulators on various makes 

 of incubators vary as to detail, but are similar in principle. 

 They depend upon the expansion of a thermostat, with rising 

 temperatures, opening a damper at the heater by means of a 



