712 
Report on the Exhibition of Implements^ 
discovery was the result of an accident. Messrs. Rouillier and 
Arnoult being compelled to leave Paris and reside in the 
country, on account of the health of one of the party, chance led 
them to Gambais, near Houdan, where poultry rearing is a 
speciality, in which they engaged, using turkeys to sit upon 
hens' eggs. One day, 40 out of 60 turkeys that were sitting, for 
some reason died. This was a most serious loss, especially as 
the chicken had been sold in advance. They were compelled 
to fulfil the contract at any cost. Under these circumstances the 
old adage of " necessity being the mother of invention," came 
into play ; they bethought them to take those eggs which were 
most advanced, and place them between two eider-down quilts, 
surrounded by bottles full of hot water. It was a great and 
continual trouble to keep up the heat, but the success was com- 
plete, and the contract kept. Whilst this was going on, 13 
partridge eggs, which had been sat upon for 15 days, were 
brought to the operators and placed with the hens' eggs, and 12 
partridges were hatched out. Attention being thus directed to 
artificial hatching, experiments were made with the incubators 
of Carbonnin and Robert. The first depended for its heat upon 
a petroleum lamp, difficult to regulate ; and in the second, in 
which apparently water was the heating medium, the tempera- 
ture could not be maintained. Thus were these experimenters 
led to the construction of their hydro-incubator, which has 
achieved in France a well-deserved success, and is now, with 
certain improvements in detail, made in this country by T. 
Christy and Co. The machine exhibited by Rouillier and 
Arnoult, at Kilburn, which was for 50 eggs, comprised a nearly 
square box 20 inches in length and width by 22 inches deep ; 
the eggs were contained in a drawer at the bottom ; at the top 
is a compartment termed the drier, in which the chicken are 
placed on hatching, and kept for 24 hours, without food. The 
water space contains 6 gallons. It is lined with zinc, and the 
space between it and the outer walls of the box is filled with 
felt. The depth of the egg drawer is 2^ inches. About 2 gallons 
of boiling water are added morning and evening, after a sigiilar 
quantity has been withdrawn ; the eggs are turned at the same 
time ; a water-gauge at the side measures the water drawn off ; 
a second tube from the water chamber allows of the escape of 
air. A certain amount of moisture is required in the egg drawer ; 
this is said to be provided for by a current of cold air from 
the outside entering the drawer by a small opening at the side, 
and condensing the moisture contained in the hot air. In the 
morning only, the eggs should be exposed for about 20 minutes. 
The artificial mother comprises a square box with legs projecting 
4J inches, this allows the chicken ingress and egress ; inside is 
