248 Rowland, Garmichael and Briggs — Rontgen Rays. 



there any from the glass of the tube where the cathode rajs 

 struck it as Rontgen thought. This tube as a source of rays 

 far exceeded all our other collection of Crookes' tubes and gave 

 the plate a full exposure at 5 or 10 cm in about 5 or 10 

 minutes with a slow-acting coil giving only about 4 sparks 

 per second. 



The next most satisfactory tube had aluminium poles with 

 ends about 3 cm apart. It was not straight but had three bulbs, 

 the poles being in the end bulbs and the passage between them 

 being rather wide. In this case the discharge was slightly 

 oscillatory but more electricity went one way than the other. 

 Here the source of rays was two points in the tube, a little 

 on the cathode side of the narrow parts. 



In the other tubes there seemed to be diffuse sources, prob- 

 ably due in part to the oscillatory discharge, but in no case did 

 the cathode rays seem to have anything to do with the 

 Rontgen rays. Judging from the first two most definite tubes 

 the source of the rays seems to be more connected with the 

 anode than the cathode, and in both of the tubes the rays 

 came from where the discharge from the anode expanded itself 

 toward the cathode, if we may roughly use such language. 



As to what these rays are it is too early to even guess. That 

 they and the cathode rays are destined to give us a far deeper 

 insight into nature nobody can doubt. 



Baltimore, Feb. 20, 1896. 



