fi48 Mr. J. L. Glasson on the Variation of Ionizing 



and enter the ionization chamber I. Both the discharge 

 tube and the ionization chamber are waxed on air-tight to 

 the two side tubes of the solenoid with beeswax and resin. 



Fi*. 1. 



© 





H' i' i' I' i' i<i' i' 

 t 



1q eqrfL 



To frump Cf.d acuye 



v/// / // ,QJ /,rj//n 



% 



To earn 



The whole apparatus could be exhausted by a Topler 

 pump and the pressure could be measured with a McLeod 

 gauge whose constants had been determined before setting- 

 up. As soon as the current is passed through the solenoid 

 the rays are bent round and separated into a spectrum as at 

 L M, and by suitably adjusting the current strength rays of 

 any desired velocity may be allowed to fall on the aperture 

 and enter the ionization chamber. 



The velocity of the rays which enter the chamber cor- 

 responding to any desired current may easily be calculated 

 wdien we know the dimensions of the solenoid, the current 

 strength, and the value of e/m. The constants of the coil 

 and the calculations are given later. 



After resolution into the magnetic spectrum a small 

 pencil of cathode rays of practically uniform velocitv enters 

 the ionization chamber through the two diaphragms a and b. 

 The hole in each of these was about \ mm. in diameter. 

 Having traversed the chamber the rays are caught in an 

 aluminium Farada}' cylinder K. The outer brass case of 

 the chamber is earthed while the Faraday cylinder can be 

 raised to a potential sufficient to saturate the gas by a 



