when an Electron escapes from Surface of a Hot Body. 207 



and crimped over at the ends so as almost completely to 

 enclose the filament. Outside connexion was made through 

 a platinum wire sealed into the glass. 



Fig. 2. 



H 



L = filament ; H = copper gauze anode. 



After a filament was mounted as described the tube was 

 attached to a rotary mercury-pump and enclosed in a vacuum 

 furnace. During exhaustion the furnace was maintained at 

 a temperature of about 600 degrees centigrade. When the 

 McLeod gauge showed a pressure of about 1 x 10 ~ 4 mm. of 

 mercury, the furnace was turned off, connexion with the 



