This temperature lag period can be reduced by warming the eggs to room temperature before they are placed into the incubator. Place the thermometer to measure the temperature at a level at or slightly above where the center of the egg will be. Although a short cooling period may not be harmful, longer periods of low temperatures will reduce the rate of embryo development. Excessively low temperatures will kill the embryos. If the temperature remains beyond either extreme for several days, hatchability may be severely reduced.
Moisture is provided by a pan of water under the egg tray.
The water surface should be at least half as large as the surface of the egg tray. Add warm water to the pan as necessary. If more humidity is needed, increase the size of the pan or add a wet sponge. Humidity adjustment can also be made by increasing or decreasing ventilation. The air cell increases in size during incubation at a rate that depends on temperature and humidity as moisture evaporates from the egg.