458 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



driving the striae into the anode, might attribute this action to an 

 actual repelling force arising from the cathode. When this suppositi- 

 tious force is diverted by a magnet, the striae reappear and 

 more current flows. One ignorant, too, of the many facts of 

 ionization by collision might further suppose that heavier 

 particles of slower motion might be held back by swifter 

 particles issuing from the cathode. These views of a mind 

 not biased by ionization theories would appear to be sup- 

 ported by the phenomena presented by the tube represented 

 in Figure 5. 



One branch of this tube is at right angles to the other 



branch. There are two anodes, 



A and A', and two perforated 

 cathodes, K and K'. When a 

 multiple circuit is formed by 

 leading in the current to the 

 two anodes and out by one 

 cathode, K, striae form in the 

 the branch AK ; and they 



Figure 5. 



branch A'K' after they disappear in 

 persist in the branch A'K' when the 

 branch AK appears to be nearly at the 

 X-Ray stage. One looking at the branch 

 A'K' would suppose that the rarefication 

 of the entire tube was low, and gazing at 

 the branch AK would think it very high. 

 The bend in the tube acts like a magnet 

 in allowing the striae to emerge from the 

 anode A' ; and it does this by enfeebling 

 by reflection the effect of the cathode rays 

 in the branch A'K'. 



The function of the cathode beam seems 

 to be twofold : it forces back the striae, 

 and at higher exhaustions it ionizes the 

 gas ; for the current ceases to flow at high 

 exhaustions when the cathode beam is 

 strongly diverted by a magnet. These 

 functions are illustrated by the phenom- 

 ena in a tube represented in Figure 6. 

 Between the anode A and a cathode D 

 the glass tube is constricted. The cathode D is a circular disc with 

 an orifice a little larger than the glass orifice. The cathode rests upon 

 the ground walls of this orifice, presenting no metallic surface toward the 

 anode A. The cathode beam produces an orange fluorescence toward 



