METHODS OF HATCHING CHICKENS 309 



duced 329 chicks, medium moisture 319, and no moisture 

 278 chicks from the same number of eggs put in. At the 

 Oregon Station (Bulletin 100) medium moisture produced 

 424 chicks, maximum 420, and no moisture 330. In each 

 case the same kind and number of eggs were used in the 

 different machines. Many subsequent experiments showed 

 similar beneficial results from the use of moisture in num- 

 ber of chicks hatched. They showed further that larger 

 and heavier chicks were hatched where moisture was used. 

 These experiments were made with a "moisture" machine. 



Amount of Moisture to Use. The experiments showed 

 that extreme dryness as well as extreme humidity were 

 alike detrimental. The amount to use depends largely 

 upon the amount of ventilation. It was also shown that 

 the range between the temperature of the incubator and 

 the room influenced the humidity of the machine. As the 

 difference increased the humidity decreased. It is this 

 difference or range of temperature between the machine 

 and the room that causes the circulation of air through 

 the machine. As the difference decreases there is less cir- 

 culation and consequently higher humidity. To maintain 

 a uniform humidity, therefore, account must be taken of 

 the range of temperature, and the supply of moisture 

 governed accordingly. One machine required double the 

 amount of supplied moisture to maintain the same humidity 

 conditions as another machine of different make, due to 

 difference in ventilation. This was shown by the reading 

 of the wet bulb thermometer. 



The Wet Bulb as a Guide for Moisture. The wet bulb 

 thermometer may be used to advantage as an indicator of 

 the proper degree of humidity in the incubator. This is 

 an ordinary thermometer, the bulb of which is covered with 

 a muslin or silk wick, one end of which is inserted in a cup 

 of water. Evaporation is a cooling process, and as the 



