42 APPLIED BACTEEIOLOGY 



maintained uniform within half a degree without readjust- 

 ment of any part for months together, and this, too, in 

 defiance of great changes of gas-pressure, and of air- 

 temperature in the room in which the apparatus is 

 working. 



Messrs. Hearson and Son have applied the above prin- 

 ciple to an incubator which is heated by means of a 

 petroleum lamp. This form is a very convenient one for 

 use in places where gas is not obtainable. 



The outer case of this apparatus is similar to the one 

 already described, save only that the woodwork on the 

 right-hand side is carried lower down to form a support 

 for the lantern in which the lamp T burns. 



The general construction of the water-jacketed chamber 

 is also the same ; but there is a large water-space below the 

 chamber to make room for a pipe L, which conveys the 

 heated products from the flame through the water and back 

 again to the lantern, the lantern being furnished with a 

 second chimney, which discharges into the open air a short 

 distance behind the one seen in the illustration. 



A is the water-jacket surrounding the chamber containing 

 the cultures. 



is the pipe through which the water-jacket is filled 

 with water. 



N is a cock for emptying the same. 



M is the overflow. 



S is the capsule contained in a case attached by a tube to 

 the lever plate outside. 



D is a lever pivoted on the left, and carrying at its free 

 end a damper P, which when resting on the chimney V 

 effectually closes it. 



P is a screw for adjusting the damper when starting the 

 apparatus. The end of this screw is concave, and into this 

 concavity is inserted the upper end of a wire, the lower end 

 of which rests on the capsule. 



