50 APPLIED BACTEKIOLOGY 



in the other incubators) to the lever M, and this lever is so 

 connected with the tube C that when the capsule expands 

 the tube moves horizontally to the left. 



At the side of the apparatus is a lantern containing an 

 open boiler, F, heated by quite a small gas or petroleum 

 lamp flame. 



The bottom of the boiler is connected with the bottom of 

 the water-jacket by a tube (not shown), so that the water 

 in the boiler always stands at the same level as that in the 

 water-jacket. The bottom of the ice vessel B has also an 

 outlet which communicates with the water-jacket above the 

 incubating chamber (not shown). 



The water-jacket is provided at the top with an overflow 

 and waste-pipe at N, through which the surplus water 

 escapes. 



The front end of the little tube C is bent downwards, and 

 immediately under the bent end are two tubes, D and E, 

 standing vertically side by side in an open vessel with a 

 short interval between them. 



The vertical tube E is connected with the top of the ice- 

 box by a tube, E', and the vertical tube D is connected with 

 the boiler P by a tube, D'. 



The valve K is connected on the right with a continuous 

 water-supply, and on the left by means of a small india- 

 rubber tube with the small tube C. 



The apparatus having been adjusted according to the in- 

 structions, the action is as follows : 



The stream of water passing the valve K flows along the 

 tube C, down the tube D, and along the tube D' to the 

 boiler F, where it is heated, and thence flows into the 

 water-jacket and increases the temperature. 



After a time the capsule expands and moves the tube C 

 to the left, thus causing the water to fall between the two 

 tubes D and E. 



