1897.] on Cathode Bays. 421 



First, let us consider for a moment the effect of magnetic force 

 on the ordinary discharge between terminals at a pressure much 

 higher than that at which the cathode rays begin to come off. 1 have 



Fig. 1. Fig. 2, 



here photographs (see Figs. 1 and 2) of the spark in a magnetic field. 

 You see that when the discharge, which passes as a thin bright line 

 between the terminals, is acted upon by the magnetic field, it is pulled 

 aside as a stretched string would be if acted upon by a force at right 



Fig. 3. Fig. 4. 



angles to its length. The curve is quite continuous, and though there^ 

 may be gaps in the luminosity of the discharge, yet there are no 

 breaks at such points in the curve, into which the discharge is bent by 

 Vol. XV. (No. 91.) 2 f 



