The " Hydro-Incubator." 181 



tion a fact, and thousands of chickens are hatched every year 

 in incubators. The bearing upon the question of poultry 

 farming is very great, as the attention given to a machine is 

 not more than is needed by a couple of hens, whilst it will 

 do four or six timos the work, and with greater certainty. 

 This has, undoubtedly, had much to do with the recent revival 

 of interest in poultry keeping, and we, therefore, are justified 

 in dealing fully with the question. 



As might naturally be expected, the hydro-incubator was 

 not allowed to have all the field to itself. If its introduction 

 had not done any other good, that of showing where the 

 mistake was in the construction of previous machines was 

 enough to earn our favour. All these machines had been 

 made on the principle of having a small tank of water above 

 the eggs, heated by a continuously burning lamp, or gas jet. 

 In some, the tank was partially embedded, but in others, it 

 was entirely exposed, and iti all it was very liable to external 

 atmospheric influences. The result of this was, that every 

 variation of the temperature affected the machine, and, during 

 sudden changes, it was almost impossible for any regulator to 

 withstand the pressure brought to bear upon it. Only one — 

 Boyle's — did actually work smoothly in this way, and that 

 was doubtless partly due to the fact, that its tank was the most 

 protected of all. This constant variation in the temperature, 

 could not but be hurtful to the eggs. But there was another 

 great evil, namely, that the rapid exhaustion of the heat, 

 consequent upon exposure, necessitated the consumption of a 

 comparatively large quantity of gas or oil, with vitiation of the 

 atmosphere already spoken of. On the introduction of the 

 hydro-incubator, therefore, it was at once seen that, with a 

 larger body of water in Ihe tank, and the tank protected from 

 external influences, the heat in the machine would be steadier, 

 the consumption of oil or gas would be very small, and the 

 vitiation of the atmosphere reduced to a minimum, or entirely 



