22 
THE POULTRY BOOK. 
rejected ; but when the clear eggs are removed on the eighth day, the proceeding 
is not required, and from the hazard of chilling the eggs by too low, or injuring 
them by too high a temperature, the plan is, in our opinion, decidedly objectionable. 
Hens’ eggs are said to hatch on the completion of the twenty-first day ; but where 
the eggs are fresh, the sitter attentive, and the weatherwarm, this period is frequently 
reduced by several hours. We should think the brood likely to turn out an indifferent 
one if, when the eggs were placed under the hen at roosting time, it did not present 
many chipped eggs at least on the evening of the twentieth day ; and the next morning 
the majority should be out and strong. The chickens are constantly heard chirruping 
within their prison some hours before the least sign of their beaks is visible, 
during which time they are at work upon their covering. Where the young bird is 
vigorous and healthy, it works round the top of the shell till it has cut out a sort 
of flap or cover, dividing the shell into two unequal parts ; the smaller one is pushed 
back, though on one side it is attached by the interior membrane to the larger ; in 
this manner exit is effected. In the morning the two parts are constantly found 
packed away, one within the other, occupying the smallest possible amount of 
room, if the hen has not already ejected them. 
“Let well alone” is here a wise maxim; but our rule is to examine how 
matters stand when the period of twenty-one days has passed ; and 
if eggs are found billed, but the chickens within in a weak state, assistance 
should be given by widening the breach. If eggs are found without any 
indication of life within, but apparently not addled, break the shell cautiously and 
as near the usual position of the bill as possible ; but we are commonly presented 
with a dead chick, or one where from weakness the yolk has not been properly 
absorbed. Its chances for life, therefore, are but slight. Strong, full-grown 
chickens are at times found lifeless, from inability to break the inner film, which in 
many cases would seem to present more difficulty than the shell itself. 
It is convenient to have two hens hatching at the same time ; for not only if 
accidents happen may the two broods be united, but on the hatching day it con- 
stantly occurs that, to prevent the newly born chicks being crushed by eggs that are 
behind time, we wish to give all that are hatched to one hen, while the other takes 
charge of the eggs alone. Not only does this give security to the chicks, who run 
great hazard of being crushed by the eggs if they are kept for any prolonged space 
under their mother, but the unhatched eggs also stand a far better chance ; for when 
a hen finds chickens under her, she sits higher from the eggs, and less warmth is 
afforded them at the time they require most. 
Having spoken at length of the sitting hen, it may be thought desirable to enter 
into the consideration of the various incubators designed for the purpose of hatching 
eggs by artificial heat. 
A very compact apparatus of this kind, for those who desire to experiment on a 
small scale, has been designed by Messrs. Crook, of Carnaby Street ; and other 
large incubators acting on the same principle have also been designed. 
We have recently been requested to examine the construction and mode of action 
