One of the latest applications of electricity Is In the construction of electric incubators and poultry-breeding apparatus. While artificial processes have for some time past been in use, in connection with poultry breeding, they have been based on the use of compartments heated by gas, alcohol, or petroleum. The apparatus here described is, however, heated and regulated directly by electric current as derived from the mains, any complicated accessories being dispensed with. The electric incubator shown in Figs. 1 and 2 has been designed by Mr. G. Kesel, of Kempten, Bavaria. In Fig. 2, which shows the apparatus opened, a wire mesh may be seen on the lid. Back of this the main radiator is arranged which takes up the whole of the lid, and which is worked only as long as the apparatus is kept closed. As the heating wires are strung out uniformly throughout the lid, all eggs are submitted to the same heating effect, regardless of their location in the drawer. The main heating body in the lid of the apparatus is assisted by auxiliary radiators placed on the bottom of the outfit, which are continuously energized even while the apparatus is opened, maintaining the hatching compartment at a uniform temperature of about 30 deg. C. (86 deg. F.) and preheating the air entering the hatching compartment. The heating coils of the apparatus are energized as soon as the contact is connected to the mains. The temperature is controlled by the automatic switch of the main radiator and the heat regulator in the hatching compartment. Supposing a temperature of 39 deg. C. (103 deg. F.) to be required in the hatching compartment, the apparatus is heated until this temperature is recorded by the thermometer, after which the contact is thrown out by turning a screw fitted outside the apparatus. After a little adjusting of the screw a point will be reached at which the temperature in the hatching compartment is kept accurately at 39.5 deg. C. (103 deg. F.) when even during several months' operation fluctuations in the hatching temperature will be less than one-tenth of a degree, the mercury of the thermometer remaining most constantly at the point of adjustment. Whether the adjustment has been properly made, may be determined by the uniform ticking motion of the switch. This uniformity of temperature is obtained - by the . automatic-switching in and out of the main radiator in the. lid of the apparatus. While the auxiliary radiators, as above mentioned, will raise the apparatus to a temperature of about 86 deg. F., the main radiator supplies the surplus heat, being thrown alternately in and out of circuit by means of the switch at a rate depending on the temperature. One of the most difficult features of artificial poultry breeding is a proper supply of fresh air. In the electrical incubator air is supplied from underneath, the entering fresh air coming in contact with the eggs after being properly pre-heated by special radiators. This ventilation is controlled by opening to a variable extent the lateral slides fixed at the top of the apparatus. When working in a heated room, the slides should be obviously opened to a greater extent than in a cold room. It should be remembered that ventilation plays the role of maintaining the life of the germ. While an ample supply of fresh air therefore is extremely valuable for the development of the germ, any excess of ventilation will prove detrimental; in fact, the surplus air will exert a drying action on the contents of the eggs. Nevertheless, it will be found more advantageous to have too much ventilation than to risk killing the germ by stifling. The incubator is provided with two thermometers, one of which is arranged in front in the drawer con-talning the eggs, and the other in the interior of the hatching compartment. The former is observed through a glass window from the front, when the apparatus is closed, while the other thermometer is read from above through the double window in the lid of the apparatus. Both thermometers can be placed at the same height; and after adjusting for the desired temperature by means of the front thermometer, the other thermometer is displaced untii the temperature recorded by it is exactly the same. A better practice, however, is to so arrange the second thermometer as to have it record one degree more than the front thermometer. The second thermometer, located in the hatching compartment, serves as an emergency safeguard. Should the heat regulator fail to work, this thermometer will regulate the temperature in Its turn by throwing the main radiator out of circuit. A much-discussed point in connection with artificial poultry breeding is the supply of moisture. The constructor of this apparatus recommends using no artificial supply of moisture, the necessary amount being always provided by a proper ventilation. Nevertheless, the construction of the apparatus allows of any amount of moisture being supplied from outside, the degree of moisture being read from a special hygrometer. Below the contact supplying the heating current, another contact box has been arranged for an incandescent lamp, which apart from lighting the apparatus, whenever required, serves for observing the actual condition of the eggs, any motion of the embryo being readily watched in the semi-transparent eggs, while foreign bodies in infertile eggs are detected. The operation of the incubator is so uniform that the time of hatching of all eggs of a given batch Is about the same, the maximum difference being two to three days. As soon as they are hatched the chicks are moved to a compartment in which they are kept for 24 hours without food. From this compartment they are taken to the electric breeding apparatus represented in Fig. 3. This is separated into two portions, one of which serves as a sleeping chamber and the other as a feeding room. The most important feature of the electric breeding apparatus is the heating plant, which can readily be connected to the ordinary lighting circuit. The radiator of the sleeping compartment is fitted to the ceiling, and is so designed as to produce a uniform radiation of heat from the ceiling, thus preventing any crowding of the chickens. Three different degrees of heat can be obtained by actuating a switch, the temperature being made to decrease from day to day. The requisite heat depends on the number of chicks contained in the apparatus. In the United States inventors have been successfully at work in this direction, and electric installations may be obtained to fit into existing oil incubators. A very ingenious adaptation has been worked out with a view to illustrate the hatching of chickens in nature classes or schools. This device is known as the "Electrehen"; an oval glass incubator, operated by the heat of an electric incandescent lamp, controlled by a delicate and sensitive thermostat which holds the temperature steadily at 103 deg. F. The "Electrehen" has a neat metal base of ornamental design, with nickel-plate, oxidized copper, or gun-metal finish, the base forming the brooder for the newly-hatched chicks. A drawer is provided, which is partly drawn from the base, and the chicks run about in the fenced inclos-ure, about three or four feet square, making a most interesting exhibit. This most attractive device is easily connected to any electric lighting circuit, either alternating or direct current, of 110 volts, by the usual flexible cord and plug. It is only necessary to turn the button, and sufficient heat is provided for hatching and brooding the chicks.
This article was originally published with the title "Electric Incubators" in Scientific American 97, 19, 336 (November 1907)