204 



POULTRY PRODUCTION 



The danger of this sort of tester when an oil lamp is used 

 is overheating the egg. This is particularly true with a 

 beginner, with whom testing is a slow process. From this 

 standpoint, an electric bulb placed in the side of a tin can 

 that has a hole of the proper size placed in the side is much 

 more satisfactory. 



Daylight testing is growing in popularity. This may be 

 done with the aid of a darkened room, at one window of 

 which an egg hole is arranged, preferably on the sunny 

 side of the building. It may also be done without the 

 darkened room by the use of a tube, as shown in Fig. 104. 



Fig. 105 



Hygrometer. (Courtesy of Taylors Instrument Company.) 



The person testing holds an egg in the sunlight at one end 

 of the tube and places the eye at the other end. The tube 

 may be of cardboard, heavy brown paper, or any other 

 material that is convenient and will shut out the light. 



Hygrometers. — The hygrometer, or wet-bulb thermometer, 

 is sometimes used to indicate the relative humidity of the 

 egg chamber. The general uncertainty as to what consti- 

 tutes proper practice with reference to introducing moisture 

 into incubators has prevented their very wide use. 



Egg-turning Devices. — Mechanical egg-turning devices 

 have not been looked on with general favor, because they 



