NO. 1863 BIBLIOGRAPHY OF CANAL RAYS — FULCHER 



323 



lHTErt5iTY -Velocity Curves. 



Fig. 63.— Doppler effect to be expected if sources of light are H gas atoms 

 hit by H canal rays of fairly uniform velocity, 



Doppler Effect, Stationary Intensity. 



Explained as due to emission of light either 



(i) By a positive atom on collision with a neutral atom which stops 

 it, the intensity being proportional to the gas density: 813(172, 430). 

 This hypothesis is not reconcilable with the existence of the intensity 

 minimum; or 



(2) By neutral atoms ionized by secondary negative rays created by 

 the canal rays: 819(398); 822(917). 



Shift Towards the Red. 



Theoretical importance in deciding between the various electromagnetic 

 theories of the emission of light by electrons in motion, those of Bucherer, 

 Einstein, and Lorentz: Sti(293). 



Emission oe Light by an Atom. 



The Doppler effect shown by light assumed to come from canal rays, 

 since it may give a means of distinguishing the light emitted by singly 

 charged atoms from that emitted by those which are neutral or doubly 

 charged, promises valuable data as to the circumstances, even the mechan- 

 ism concerned in this radiation of light. However, no theories advanced so 

 far explain satisfactorily the phenomena observed, hence deductions from 

 them seem premature. The theories are as numerous as the writers and 

 at the present stage, it seems unnecessary to attempt the difficult task of 

 abstracting them, but a partial list of articles on the emission of light by 

 an atom based on the results of investigations with canal rays is sub- 

 joined: 88(104, 109); 810(251, 253); 812(360); 813(40, 174, 422, 432); 

 Hl2(i7-20); Wii(428, 437); Si6(8o) ; 8W; Ps2(259) ; Sti ; 812(683); 

 S22. Also — 



