INCUBATION, ARTIFICIAL. The Egyptians have from time immemorial been accustomed to hatch eggs by artifi cial warmth, without the aid of hens, in stoves, called Mammals. The inhabitants of the village Berme still travel through the most distant pro vinces of Egypt at certain seasons or the year, with a portable furnace, heated by a lamp, and either hatch chickens for sale, or undertake to hatch the eggs be longing to the natives at a certain rate per dozen. M. de Reaumur published in France, about a century ago, some inge nious observations upon this subject ; but M. Bonnemain was the first person who studied with due attention all the circumstances of artificial incubation, and mounted the process successfully upon the commercial scale. So far back as 1777 lie communicated to the Academy of Sciences an interesting fact, which he had noticed, upon the mechanism em ployed by chicks to break their shells; and for some time prior to the French revolution he furnished the Parisian mar ket with excellent poultry at a period of the year when farmers had ceased to supply it. His establishment was ruined at that disastrous era, and no other has ever since been constructed or conducted with similar care. There can be no doubt however of the practicability and profit ableness of the scheme, when judiciously managed. Some imitations of his plans have been made in England, but how far they have succeeded, in an economical point of view, it is difficult to determine. His apparatus derives peculiar interest from the fact that it was founded upon the principle of the circulation of hot water, by the intestine motions of its in a returning series of con nected pipes ; a subject afterwards illus trated in the experimental researches Count Rumford. It has of late years been introduced as a novelty, and applied to warm the apartments of many pnblic and private buildings. They were then publicly exhibited at his residence in Paris, and were afterwards communicated to the world at large in the interesting article of the Dktionnaire Technologique, entitled Incubation Artificzelle.
The apparatus of M. Bonnemain con sisted, 1. of a boiler and pipes for the circulation of water ; 2. of a regulator calculated to maintain an equable temper ature; 3. of a stove-apartment, heated constantly to the degree best fitted for incubation, which he called the hatch ing pitch. He attached to one side a
pousginire or chick-room, for cherishing the chickens during a few days after in cubation.
The boiler is represented in vertical section. It is composed of a double cyl inder of copper or cast-iron, 11, having a grate, b (see plan), an ashpit at d. The water occupies the shaded space, c, c. h, g, g, e, e, are five vertical flues, for con ducting . the burnt air and smoke, which first rise in the two exterior flues, e, then descend in the two adjoining flues g,g, and fi nally re-mount through the passages i, in the central flue h. During this up wards and downwards circulation, as shown by the arrows in the section, the products of combustion are made to im part nearly the whole of their heat to the water by which they are surrounded. At the commencement, some burning paper or wood shavings are inserted at the ori fice m, to establish a draught in this cir cuitous chimney. The air is admitted into the ashpit at the side, in regulated quantities, through a small square door, moveable round a rod which runs hori zontally along its middle line. The swing valve is acted upon by an expanding bar, which opens it more or less, according to the temperature of the stove apartment in which the eggs are placed.
D is the upper orifice of the boiler, by which the hotter and consequently lighter particles of the water continually ascend, and are replaced by the cooled particles, which enter the boiler near its bottom.
When it is wished to hatch eggs with this apparatus, the fire is kindled, and when the temperature is 100°, the eggs are introduced : only one twentieth of the whole number on the first day ; next day a like number is laid in the trays, and thus in succession for twenty days, so that at the end of this time those first placed will be hatched, and daily after wards an equal number of chicks may be obtained. While thus hatching, a little of the water of the shell is evaporated and replaced by air, which becomes need ful for respiration. After the chicks are hatched, they are transferred to the chick-room, which contains a small vessel filled with millet seed for the sup port of the chicks.