AN INCUBATOR HOUSE 13 



covered with dirt tlie temperature within in the summer 

 will be about sixty-five degrees. 



Sixth. The volume of air in the wliole room should be 

 great enough so that the air will not become poluted with 

 the lamp" gas before the ventilators can remove the latter. 

 It should be between seven and eight feet from floor to ceil- 

 ing, which will give the desired volume. 



Atmospheric air is not a simple substance, but a mechani- 

 cal mixture. Oxygen and nitrogen, the principal consti- 

 tuents, are present in very nearly .the proportion of one 

 part of oxygen to four parts of nitrogen by weight. Oxygen 

 is one of the most important elements in the air; it is the 

 active element in the chelnical process of combustion and 

 a somewhat similar process takes place in the lungs of human 

 beings. The larnp on the incubator, while burning, con- 

 sumes the oxygen in the air and throws off a gas called 

 carbon dioxide or carbonic acid gas. Being 1.5 heavier 

 than air it fall§ to the floor and there piles up like water 

 filling a hole unless removed as fast as it is formed. This 

 is the reason that the middle ventilator (see Fig. II) extends 

 to within six inches of the floor and does not terminate 

 near the roof like the first and third. If this gas is allowed 

 to accumulate in the building it will get into the egg chamber 

 of the incubator as nearly all incubators take in fresh air 

 near the floor. -If this gas is allowed to appear in quantity 

 and allowed to remain long it will kill all the living germs 

 in the eggs. I do not doubt that this is the cause of many 

 failures with incubators. Having lea'rned the main essen- 

 tials of an incubator house, the mechanical construction 

 comes next in order. This is a simple matter for the great- 

 est problem is to know in what manner to build it. - 

 Making the Excavation. 



After the, frost is out of the ground in the spring, select 

 some high and dry spot and dig a rectangular hole in the 

 ground 9x11x4 feet, have the sides sloping so that the 

 floor of the cellar will be 8 x 10 feet. This should be dug 

 with the long way east and west. At the center of the west 

 end dig out the place for the stairs. At the surface this 

 should measure 3x6. If in clay soil the steps may be made 

 by digging the clay in the form of steps. These steps 



