420 Mr. A. Mtillcr on an X-Ray Bulb 



of a bottle from which the bottom had been cut off, and 

 replaced by an aluminium disk which had a hole in the 



Fig-. 1. 



A A c//s A 



Copper roc/. 



centre. The disk was sealed to the bottle with sealing-wax. 

 The second part B was made of brass, and connected with a 

 Gaede pump. A water-jacket served to cool the joint 



