THE MAMMOTH INCUBATOR AND BROODER 431 



dead embryo or egg, in which there is no Hfe, is much cooler, 

 thus the exact temperature of the incubating eggs are not 

 recorded. Some makers now construct the thermometers with 

 the bulb exposed so that it is easy to bring the bulb in direct 

 contact with the eggs. 



The automatic regulation is necessary to successfully meet 

 ordinary conditions. In the early spring the weather fluctuates 

 from extreme cold spells to very warm weather, which often 

 makes changes in the temperature of 15 to 20 degrees in a few 

 hours. Frequent high winds come up in a few minutes, and 

 with the wide variations it is practically impossible to keep 

 anything Hke a uniform cellar temperature. 



Having a thermostat just above the eggs it expands with 

 heat and contracts with cold, thus accurately controlling the 

 heat. Thus, if too much heat accumulates in the egg chamber 

 the ventilator is opened and the excess is allowed to radiate off. 



The exterior of the machines is constructed of wood, as 

 chestnut, walnut, or oak. The material should be tonged and 

 grooved, and the parts insulated to prevent any cracks admit- 

 ting a draft of cold air directly upon the eggs. 



The stove or heater is usually constructed with a round base 

 which sets squarely on the floor. The ash doors and drafts fit 

 tight, so that when closed there is no air admitted. The grates 

 are usually of the sliding and slicing type, which permits of the 

 ready removal of chnkers. The heater pot and water cyhnder 

 should be cast in one piece. There should be ample water 

 capacity to ensure quick circulation and a steady flow of water. 



A draft regulator is arranged in the heater top. This con- 

 sists of a check door in front and a griddle seating directly on 

 ■ the top of the water jacket. With the front door closed the 

 griddle is raised, allowing the fire to burn faster. As the 

 griddle seats the front door opens. 



When the front door of the stove is opened, air from the room 

 is drawn over the top and up the chimney, indirectly assisting 

 in the ventilation of the cellar. 



In the heater pipes the same water is used over and over 

 again. 



When desired electric lights are provided, drawing their 

 current from dry-cell batteries. Small bulbs are attached 



