46 APPLIED BACTERIOLOGY 



H is a lead Weight for bringing more or less pressure to 

 bear on the capsule. 



K is the thermometer, the bulb of which is inside and the 

 scale outside the heated chamber. 



The apparatus having been adjusted according to the 

 instructions, the action is as follows : 



The heated products of combustion, not being able to find 

 any exit at the chimney V, pass along the flue L, and, 

 parting with the greater portion of their heat en route, 

 return again to the lantern by a flue behind and parallel 

 with the one seen in the section, and are thence conducted 

 into the open air by a second chimney placed in the lantern 

 a short distance behind the one covered by the damper F. 



The products of combustion continue to move in this 

 direction until the water, and consequently the chamber, 

 are sufficiently heated to distend the capsule. 



When this point is reached, the wire between S and P will 

 be pushed up by the capsule, and the lever will cause the 

 damper to rise more or less off the chimney V. In a short 

 time the damper will be found to hang steadily in one 

 position, and on examining the thermometer at intervals, 

 the inside of the chamber will be found to remain steadily 

 at one temperature. 



The precautions to be observed with this incubator are 

 much the same as those required in working with an 

 incubator which acts with an Excelsior valve, and the 

 temperature is adjusted in the same manner by moving the 

 lead weight ; but to make the matter quite clear we append 

 the following instructions for working. 



Instructions foe woeking an Incubatoe heated by 

 A Lamp. 



22. Fill the tank with water at least 5° colder than the 

 boiling-point of the capsule. 



