" Hearsoris Incubator." 185 



the hydro-incubators if we were working on a large scale, in 

 which case the supply of boiling water could be easily pro- 

 vided for, we are almost inclined to think that the self-heating 

 machines are better for those who do not wish to conduct 

 operations so extensively. The latter are certainly much easier 

 to work, and are very little more costly than the others. The 

 greatest dangers are in over-heating, and, in the case of lamp 

 machines especially, making the air in the apartment where 

 it is kept impure — a danger which can be obviated to a large 

 extent, by the exercise of a little care in the working of the 

 machine, and by having the room well ventilated. 



One of the best machines of this class, is that known as 

 Hearson's, made by the Sun Auto-Pneumatic Company, of 

 Southwark. We have heard the very highest testimonies as 

 to its capabilities, and recently heard a gentleman, who 

 has about a dozeu incubators of various kinds, say that he 

 prefers this one to all the others. Above the lamp, which 

 is placed at one side of the machine, is a chimney, which has 

 two outlets. The first of these is immediately over the 

 lamp, but the other runs through the water-tank and back 

 again, the top of which is the side of the one first named. 

 There is no boiler above the lamp, and the only method of 

 heating is by means of the hot air passing through this 

 longer chimney, for, when in operation, a cap fits on to the 

 shorter one, and the heated air cannot escape in that way, 

 except under such circumstances as we shall presently indi- 

 cate. Below the tank, and just above the egg-drawer, is a 

 metal capsule about two inches square, and in this is some 

 fluid, unknown except to the makers, which expands enor- 

 mously when the heat rises to more than 10 i degrees. On 

 the upper side is a rod, which passes up a tube through the 

 tank, communicating, by a lever, with another rod, which is 

 attached to the cap fitting on to the chimney immediately 

 above the lamp. When the machine is in its normal con- 



