INCUBATORS 



' (57 



of the burner alight. This point can be varied either by 

 a sliding tube, in Page's, or by a screw, in Reichert's, so 

 that the temperature may be set at any desired point. In 

 Hearson's incubator, which is one of the best forms, the 



FIG. 1'). Hearson's incubator. 



regulator consists of a capsule containing a fluid of a 

 certain boiling-point, which when ebullition takes place 

 raises a lever and so partially cuts off the gas supply. 

 While the Hearson regulator is a very constant one, it 

 has the disadvantage that it can only be used for a range 

 of temperature of a few degrees unless the capsule be 



