THE COOL INCUBATOR 



5] 



In this case the water is collected in the open vessel in 

 which the tubes D and E stand, and is conducted by the 

 pipe H H' to the waste-pipe N without producing any 

 effect whatever on the incubating chamber. 



If the temperature of the room in which the incubator is 

 placed is above the boiling-point of the capsule, the 

 horizontal tube will continue to travel towards the left, so 

 that presently the water will run down the tube E , along the 

 tube E', and, passing through the ice-box, will so lower the 



Fig. 10. — Plan of Cool Incubator. 



inside temperature that the capsule will collapse a little and 

 cause the flowing water to again take up a position midway 

 between the two tubes. 



A fraction of a degree is quite sufficient to determine 

 which tube the water will fall into, so that the interior of 

 the apparatus remains at a practically uniform tempera- 

 ture. 



We have thus, so to speak, a reservoir of heat in the 

 boiler and a reservoir of cold in the ice-box, which the 



