none until the tenth ; E., until the sixteenth ; F., 

 until the nineteenth. G. uses water surface equal 

 to three-fourths the area of the egg chamber ; H., 

 five-eighths; I., one-half; J., three-eighths; K., 

 one- fourth ; L., one-fifth ; M., one- twelfth. N. will 

 evaporate twelve quarts of water in the egg cham- 

 ber during one hatch ; O. will evaporate one pint. 



Any one of the above may be exactly right for 

 some incubator, at some particular time, in some 

 certain place, climate or season, and with certain 

 kind of eggs, and it may never, in the experience 

 of the operator, be right again. 



How then are we to know the amount of moisture 

 to use ? If it is right at one time, why not always ? 



It might be right always . with one particular 

 incubator and the same kind of eggs, if the tem- 

 perature and humidity of the outside atmosphere 

 were always the same ; but you know that is not 

 the case. You cannot find two periods of three 

 weeks each in which the twenty-one days of one 

 will even average the same as the twenty- one days 

 of the other, in any location, in a lifetime. There- 

 fore there must be a vast difference in hatching, 

 both with incubators and with hens. 



For instance, we take a hot water incubator 

 which has an opening valve for the escape of hot air 

 from the egg chamber when the heat rises above a 

 given point. No matter what size the opening 

 may be, how large or small the moisture pans, or 

 when the moisture pans are filled, on a hot day or 

 when the lamp flame has been a little too high, 

 this valve or escape will open, and from ten to 

 65 



