Produced by Bontgen Rays. 



occurred, in order to detect any lack of uniformity in the 

 of the apparatus. 



45 



action 



Calibration of Pendulum. 



In order to ascertain the time intervals during which the 

 ions were allowed to recombine when the switch which applied 

 the field to the gas was placed at various positions along the 

 path of the pendulum, the following method was used : 



The switches S and F which applied the X-ray flash and the 

 field respectively were connected as shown in fig. 2. Both 

 switches were initially closed, and the double pole switch A 

 was closed at CD, putting a standard condenser E in series with 



Fig. 2. 



s , 





F , 



X u 



c„ 



Y Y 



n a 



A 



the switches S and F. The pendulum was then released, open- 

 ing the switch S and thus permitting a storage cell E to charge 

 the condenser through a known high resistance R. The 

 charging continued until the pendulum opened the switch F 

 which breaks the charging circuit. The condenser was then 

 allowed to discharge through a galvanometer by closing the 

 double throw switch A in the opposite direction. 



The time required by the pendulum to swing from the switch 

 S to the switch F was then computed by means of the formula 



CR 



log (l - 



CE/ 



\oge 

 where 



C = capacity of condenser. 



q = charge received by condenser as measured by ballistic 



galvanometer. 

 E = potential of battery. 

 e — base of Naperian logarithms. 

 B. = resistance in charging circuit. 



