424 PRACTICAL DIRECTIONS. [APP. 



On the whole however we have found it more 

 convenient to use a good artificial incubator. We 

 have ourselves used with success two different 

 incubators. One made by the Cambridge Scientific 

 Instrument Company, and the other by Wiesnegg 

 of 64, Rue Gay-Lussac, Paris (Fig. 65 in his 

 catalogue for 1881). We have had the longest ex- 

 perience with the former, and have found it work 

 exceedingly well : liaving been able to hatch chicks 

 without more attention than now and then turning 

 over the eggs. 



Both these incubators consist essentially of a 

 large water-bath fitted with a gas regulator. They 

 are both perfectly automatic and when once regu- 

 lated require no further attention. 



The temperature within the incubator should 

 be maintained at from 37" to 40''C. A rise above 

 40" is fatal ; but it may be allowed to descend to 

 35 or in the young stages lower, without doing 

 any further harm than to delay the development. 



The products of the combustion of the gas 

 should be kept as much as possible from the eggs, 

 while a sujyply of fresh air and of moisture is 

 essential. 



Tolerably satisfactory results may be obtained with 

 an ordinary chemical double-jacketed drying water-bath, 

 thoroughly covered in with a thick coat of cotton wool 

 and flannel baize, and heated by a very small gas-jet. 

 If the vessel be filled with hot water, and allowed to cool 

 down to 40** or thereabouts, before the eggs are introduced, 

 a very small gas flame will be sufiicient to maintain the 

 requisite temi^erature. A small pin-hole-nozzle, giving 

 with ordinary pressure an exceeding narrow jet of flame 

 about two inches high, is the most convenient. By turn- 

 ing the gas off or on, so as to reduce or mcrease the height 



