INCUBATORS HEATED BY COAL GAS 



63 



FIG. 51. Babes' incubator, fitted with a Chancel regulator. 



B. Babes' incubator. One of the simplest forms of incubator is that 

 known as Babes'. It consists of a metal box covered with a layer 

 of felt, and heated by a gas flame the height 



of which is controlled by one or other of 

 the many forms of regulators devised for the 

 purpose (p. 59). 



C. D' Arson val's incubator. The control of the 

 temperature in d' Arson val's incubator depends 

 upon the changes of shape which an elastic lamina 

 undergoes under the influence of changes of pres- 

 sure. 



The incubator is surrounded by a water jacket 

 (2, fig. 52), of which the outer wall is closed below 

 by a flexible sheet of steel, (3, fig. 52), which also 

 forms the roof of a chamber, 10, into which a tube, 

 12, connected with the gas supply passes. From 

 this chamber the gas reaches the burners through 

 two tubes, 13 and 13'. The end of the tube, 12, 

 can be made to approach or recede from the steel 

 lamina, 3, by means of a screw. When the tube 

 touches the steel the gas is completely cut off, 

 and conversely, when they are separated the gas 

 can pass freely to the burners. 



The space between the two walls is hermetically 

 sealed everywhere, except above where an opening, 

 5, is left for the purpose of filling the space with 

 water. Suppose it be required to regulate the 

 apparatus for a temperature of 37 C. The tube, 

 12, is screwed down away from the steel lamina, 

 3, so that the gas burns with a full flame. When 



the thermometer in the incubator registers 36 C., FlG 53. D'Areonyal's incubator 

 the tube is raised towards the lamina so that .the section. 



