928 Prof. G. T. Knipp on Rays of Positive 



A much more accurate one would be given by the 

 application of the Schwarzian transformation * ; however, 

 the necessarily large distance apart of the plates forming 

 the boundaries of the electrostatic field makes the application 

 of this transformation difficult if not quite impossible. 



From the theory of the action of magnetic and electric 

 fields on electrified carriers in motion we have the equations 



■1 X ^ — - v — <?/ 

 x B ~ xtt~ x 



u 



— ~ ^2? 



e __ y A _ ?/■ 

 in x B x 



where A and B are constants depending upon the electric 

 and magnetic fields and the geometrical data of the discharge- 

 tube. The constant A may be written as the product of two 

 constants thus 



A=XK 1 , 



where X is the potential difference divided by the distance 

 between the plates, and K x is a constant depending solely 

 upon the geometrical data of the discharge-tube. For the 

 reason stated above the value of K^ for my apparatus as 

 given by equation (1) is in question. I determined it 

 experimentally by passing a beam of cathode rays through 

 the system and measured the electrostatic displacement on 

 the photographic plate, and also the minimum spark potential 

 required to produce this displacement. These together with 



^=l-7xl0 7 



m 



for cathode rays gave the value 



Ki (corrected) =l - 87, 



against 



a 



Kj (uncorrected) =1*8. 



The corrected value of K x w r as used in the calculation of the 

 data that follow. 



All the photographs show tw r o and on several plates three 

 and four lines. These vary greatly in sharpness and 

 intensity from plate to plate. Two types of curves were 

 obtained. First those that are straight lines passing out 

 from the. origin, and second parabolas having their heads in 

 the same vertical line. 



Curves of the first type are the most likely to occur 



* J. J. Thomson, Phil. Mag. vol. xx. Oct. 1910. 



