Eggs for sitting should be under a fortnight old, if possible, and never more than a month. Fresh eggs hatch in proper time, and, if good, produce strong, lively chicks; while stale eggs are hatched sometimes as much as two days later than new laid, and the chickens are often too weak to break the shell, while of those well out fewer will probably be reared. It is certain, as a general rule, that the older the egg the weaker will be its progeny. Every egg should be marked by a pencil or ink line drawn quite round it, so that it can be known without touching, and if another be laid afterwards it may be at once detected and removed, for hens will sometimes lay several after they have commenced sitting. Place the eggs under the hen with their larger ends uppermost.
Let the hen be well fed and supplied with water before putting her on the nest. Whole barley and soft food, chiefly barley-meal and mashed potatoes, should be given to her when she comes off the nest, and she must have as much as she will eat, for she leaves the nest but once daily, and the full heat of the body cannot be kept up without plenty of food; or she may have the same food as the general stock. A good supply of water must be always within her reach. A good-sized shallow box or pan, containing fine coal-ashes, sand, or dry earth, to cleanse herself in, should always be ready near to the nest. She should be left undisturbed, and, as far as possible, allowed to manage her own business. When a hen shows impatience of her confinement, and frequently leaves the nest, M. Parmentier advises that half only of her usual meal should be given, after which she should be replaced on the nest and fed from the hand with hemp or millet seed, which will induce her to stay constantly on her eggs. Others will sit so long and closely that they become faint for want of food. Such hens should not be fed on the nest, but gently induced with some tempting dainty to take a little exercise, for they will not leave their eggs of their own accord, and feeding on the nest has crippled many a good sitter. It is not healthy for the hen to feed while sitting on or close by the nest, for she requires a little exercise and rolling in the dust-heap, as well as that the eggs should be exposed for the air to carry off any of that stagnant vapour which M. Réaumur proved to be so destructive to the embryo chickens; and it has also been shown by physiologists that the cooling of the eggs caused by this absence of the hen is essential to allow a supply of air to penetrate through the pores of the shell, for the respiration of the chick. When there are many hens sitting at the same time, it is a good plan to take them off their nests regularly at the same time every morning to feed, and afterwards give them an opportunity to cleanse themselves in a convenient dusting-place, and, if possible, allow them exercise in a good grass run. A hen should never be caught, but driven back gently to her nest.
A good hen will not stay away more than half an hour, unless infested with vermin, from want of having a proper dust-heap. But hens have often been absent for more than an hour, and yet have hatched seven or eight chickens; and instances have been known of their being absent for five and even for nine hours, and yet hatching a few. The following remarkable instance is recorded by an excellent authority: "Eggs had been supplied and a sitting hen lent to a neighbour, and, when she had set in a granary ten days, she was shut out through the carelessness of a servant. Being a stranger in the farmyard, the hen was not recognised, but supposed to have strayed in from an adjoining walk, and thirty hours elapsed before it was discovered that the hen had left her nest. The farmer's wife despaired of her brood; but, to her surprise and pleasure, eight chickens were hatched. The tiled roof of the granary was fully exposed to the rays of the sun, and the temperature very high, probably above 80 deg. during the day, and not much lower at night." Valuable eggs, therefore, should not be abandoned on account of a rather lengthened absence; and ordinary eggs should not be discarded as worthless if the hen has already sat upon them for a fortnight or so; but if she has been sitting for only a few days, it is safer to throw them away, and have a fresh batch.
During the hen's absence, always look at the eggs, remove any that may have been broken, and very gently wash any sticky or dirty eggs with a flannel dipped in milk-warm water. See that they are dry before putting them back. If the nest is also dirty, replace it with fresh material of the same kind. Gently drive the hen back to her nest as quickly as possible, to prevent any damage from the eggs becoming chilled. If a hen should break an egg with her feet or otherwise, it should be removed as soon as it is seen, or she may eat it, and, liking the taste, break and eat the others. Some hens have a bad habit of breaking and eating the eggs on which they are sitting, to cure which some recommend to boil an egg hard, bore a few holes in it, so that the inside can be seen, and give it while hot to the culprit, who will peck at the holes and burn herself; but hens with such propensities should be fattened for the table, for they are generally useless either for sitting or laying.
Some persons examine the eggs after the hen has sat upon them for six or seven days, and remove all that are sterile, by which plan more warmth and space are gained for those that are fertile, and the warmth is not wasted upon barren eggs. They may be easily proved by holding them near to the flame of a candle, the eye being kept shaded by one hand, when the fertile eggs will appear dark and the sterile transparent. Another plan is to place the eggs on a drum, or between the hands, in the sunshine, and observe the shadow. If this wavers, by the motion of the chick, the eggs are good; but if the shadow shows no motion, they are unfertile. If two hens have been sitting during the same time, and many unfertile eggs are found in the two nests, all the fertile eggs should be placed under one hen, and a fresh batch given to the other. The eggs should not be moved after this time, except by the hen, more especially when incubation has proceeded for some time, lest the position of the chick be interfered with, for if taken up a little time before its exit, and incautiously replaced with the large end lowermost, the chicken, from its position, will not be able to chip the shell, and must therefore perish. The forepart of the chicken is towards the biggest end of the egg, and it is so placed in the shell that the beak is always uppermost. When the egg of a choice breed has been cracked towards the end of the period of incubation, the crack may be covered with a slip of gummed paper, or the unprinted border that is round a sheet of postage stamps, and the damaged egg will probably yet produce a fine chick.
It is a good plan to set two hens on the same day, for the two broods may be united under one if desirable, and on the hatching day, to prevent the newly-born chickens being crushed by the unhatched eggs, all that are hatched can be given to one hen, and the other take charge of the eggs, which are then more likely to be hatched, as, while the chickens are under the hen, she will sit higher from the eggs, and afford them less warmth when they require it most.
The hen of all kinds of gallinaceous fowls, from the Bantam to the Cochin-China, sits for twenty-one days, at which time, on an average, the chickens break the shell; but if the eggs are new laid it will often lessen the time by five or six hours, while stale eggs will always be behind time. For the purpose of breaking the shell, the yet soft beak of the chicken is furnished, just above the point of the upper mandible, with a small, hard, horny scale, which, from the position of the head, as Mr. Yarrell observes, is brought in contact with the inner surface of the shell. This scale may be always seen on the beaks of newly-hatched chickens, but in the course of a short time peels off. It should not be removed. The peculiar sound, incorrectly called "tapping," so perceptible within the egg about the nineteenth day of incubation, which was universally believed to be produced by the bill of the chick striking against the shell in order to break it and effect its release, has been incontestably proved, by the late Dr. F. R. Horner, of Hull, in a paper read by him before the British Association for the Advancement of Science, to be a totally distinct sound, being nothing more than the natural respiratory sound in the lungs of the young chick, which first begins to breathe at that period. Of course there is also an occasional sound made by the tapping of the beak in endeavouring to break the shell.
The time occupied in breaking the shell varies, according to the strength of the chick, from one to three hours usually, but extends sometimes to twenty-four, and even more. "I have seen," says Réaumur, "chicks continue at work for two days together; some work incessantly, while others take rest at intervals, according to their physical strength. Some, I have observed, begin to break the shell a great deal too soon; for, be it observed, they ought, before they make their exit, to have within them provision enough to serve for twenty-four hours without taking food, and for this purpose the unconsumed portion of the yolk enters through the navel. The chick, indeed, which comes out of the shell without taking up all the yolk is certain to droop and die in a few days after it is hatched. The assistance which I have occasionally tried to give to several of them, by way of completing their deliverance, has afforded me an opportunity of observing those which had begun to break their shells before this was accomplished; and I have opened many eggs much fractured, in each of which the chick had as yet much of the yolk not absorbed. Some chicks have greater obstacles to overcome than others, since all shells are not of an equal thickness nor of an equal consistence; and the same inequality takes place in the lining membrane, and offers still greater difficulty to the emergent chick. The shells of the eggs of birds of various species are of a thickness proportionate to the strength of the chick that is obliged to break through them. The canary-bird would never be able to break the shell it is enclosed in if that were as thick as the egg of a barn-door fowl. The chick of a barn-door fowl, again, would in vain try to break its shell if it were as thick and hard as that of an ostrich; indeed, though an ostrich ready to be hatched is perhaps thrice as large as the common chick, it is not easy to conceive how the force of its bill can be strong enough to break a shell thicker than a china cup, and the smoothness and gloss of which indicate that it is nearly as hard—sufficiently so to form, as may be often seen, a firm drinking-cup. It is the practice in some countries to dip the eggs into warm water at the time they are expected to chip, on the supposition that the shell is thereby rendered more fragile, and the labour of the chick lightened. But, though the water should soften it, upon drying in the air it would become as hard as at first. When the chick is entirely or almost out of the shell, it draws its head from under its wing, where it had hitherto been placed, stretches out its neck, directing it forwards, but for several minutes is unable to raise it. On seeing for the first time a chick in this condition, we are led to infer that its strength is exhausted, and that it is ready to expire; but in most cases it recruits rapidly, its organs acquire strength, and in a very short time it appears quite another creature. After having dragged itself on its legs a little while, it becomes capable of standing on them, and of lifting up its neck and bending it in various directions, and at length of holding up its head. At this period the feathers are merely fine down, but, as they are wet with the fluid of the egg, the chick appears almost naked. From the multitude of their branchlets these down feathers resemble minute shrubs; when, however, these branchlets are wet and sticking to each other, they take up but very little room; as they dry they become disentangled and separated. The branchlets, plumules, or beards of each feather are at first enclosed in a membranous tube, by which they are pressed and kept close together; but as soon as this dries it splits asunder, an effect assisted also by the elasticity of the plumules themselves, which causes them to recede and spread themselves out. This being accomplished, each down feather extends over a considerable space, and when they all become dry and straight, the chick appears completely clothed in a warm vestment of soft down."
If they are not out in a few hours after the shell has been broken, and the hole is not enlarged, they are probably glued to the shell. Look through the egg then, and, if all the yolk has passed into the body of the chicken, you may assist it by enlarging the fracture with a pair of fine scissors, cutting up towards the large end of the egg, never downwards. "If," says Miss Watts, "the time has arrived when the chicken may with safety be liberated, there will be no appearance of blood in the minute blood-vessels spread over the interior of the shell; they have done their work, and are no longer needed by the now fully developed and breathing chick. If there should be the slightest appearance of blood, resist at once, for its escape would generally be fatal. Do not attempt to let the chicken out at once, but help it a little every two or three hours. The object is not to hurry the chicken out of its shell, but to prevent its being suffocated by being close shut up within it. If the chick is tolerably strong, and the assistance needful, it will aid its deliverance with its own exertions." When the chicken at last makes its way out, do not interfere with it in any way, or attempt to feed it. Animal heat alone can restore it. Weakness has caused the delay, and this has probably arisen from insufficient warmth, perhaps from the hen having had too many eggs to cover thoroughly, or they may have been stale when set. Should you have to assist it out of the shell, take it out gently with your fingers, taking great care not to tear any of its tender skin, when freeing the feathers from the shell.
Mr. Wright says: "We never ourselves now attempt to assist a chick from the shell. If the eggs were fresh, and proper care has been taken to preserve moisture during incubation, no assistance is ever needed. To fuss about the nest frets the hen exceedingly; and we have always found that, even where the poor little creature survived at the time, it never lived to maturity. Should the reader attempt such assistance, in cases where an egg has been long chipped, and no further progress made, let the shell be cracked gently all round, without tearing the inside membrane; if that be perforated, the viscid fluid inside dries and glues the chick to the shell. Should this happen, or should both shell and membrane be perforated at first, introduce the point of a pair of scissors and cut up the egg towards the large end, where there will be an empty space, remembering that, if blood flows, all hope is at end. Then put the chick back under the hen; she will probably squeeze it to death, it is true—it is so very weak; but it will never live if put by the fire, at least we always found it so. Indeed, as we have said, we consider it quite useless to make the attempt at all."