PHEASANTS IN COVERT AND AVIARY 



within the shell, whereas excess of moisture in the chamber 

 diminishes evaporation inside the shell, and the embryo dies 

 through a modified form of suffocation. 



The condition of the surrounding atmosphere in relation- 

 ship to the ventilation must be taken into consideration ; for 

 instance, if the air in the room is too dry, more moisture 

 must be allowed, whereas if inclined to be damp, the opposite 

 is applicable. The water-tank should be replenished with 

 water at a temperature of 1 20°, though some incubators are 

 what are known as "non-moisture machines," but even 

 these are usually sold with a water-tray. Either gas or oil 

 are the usual heating media, the latter being as a rule the 

 most convenient and the one in most general use. The 

 best paraffin only to be used, and the trimming of the lamp, 

 its replenishment with oil, etc., are all details of importance. 



In order to judge accurately of the temperature, the bulb 

 of the thermometer must be kept just above the eggs, and 

 not touch them, otherwise there will be a difference in the 

 temperature between that of the eggs and the air above 

 them. It, the bulb, should be about half an inch above the 

 level of the eggs within the drawer. 



As previously stated, all unfertile eggs should be removed 

 after testing them, either with the appliance depicted in the 

 illustration, or by means of a piece of cardboard, blackened 

 on one side, and with a hole cut in the middle, slightly 

 smaller than the egg. 



The egg is held between the fingers lengthwise over the 

 aperture, and the dark side of the cardboard facing the 

 observer, and the lighted lamp on the other side, so that 

 all unfertile eggs, when viewed in this manner, are seen to 

 be "clear," whereas those containing chicks will be quite 

 dark, excepting at the air space. 



There are many other inventions on the market for th6 



140 



