The person to run the incubator is the first condition of its success. A good incubator requires attention twice a day. One person should give this attention, and must give it regularly and carefully. The farmer's wife or some younger member of the family can often give more time and interest to this work than can the farmer. The likelihood of a person's success with artificial hatchers can best be determined by himself. The best location for an incubator is a moderately damp cellar. The next choice would be a room in the house away from the fire or from windows. Drafts of air blowing on the machine are especially to be avoided. Not only do they affect the temperature directly, but cause the lamp to burn irregularly, and this may result in fire. The objects in view in building an incubator are: (1) To keep the eggs at a proper temperature (103 degrees on a level with the top of the eggs). (2) To cause the evaporation of moisture from the eggs at a normal rate. (3) To prevent the eggs from resting too long in one position. The case of the incubator should be built double, or triple-walled, to withstand variation in the outside temperature. The doors should fit neatly and be made of double glass. The lamp should be made of the best material, and the wick of sufficient width that the temperature may be maintained with a low blaze. The most satisfactory place for the lamp is at the end of the machine, outside the case. Regulators composed of two metals, such as aluminum and steel, are best. Wafers filled with ether or similar liquid are more sensitive but weaker in action. Hard-rubber bars are frequently used. The most practical system of controlling evaporation is a system of forced ventilation, in which the air is heated around the lamp-flue and passes through the egg-chamber at a rate determined by ventilators in the bottom of the machine. With the outside air cold and dry only slight current is required, but as the outer air becomes warmer or damper more circulation is needed. Turning the egg is not the work that many imagine it to be. It is not necessary that the egg be turned with absolute precision and regularity. An elaborate device for this work is useless. The trays will need frequently to be removed and turned around or shifted, and the eggs can be turned at this time by lifting out a few on one side of the tray and rolling the others over. Two other points to be considered in the incubator are: A suitable nursery or place for the newly hatched chick, and a good thermometer. Rearing Chicks.