382 Intelligence and Miscellaneous Articles. 



no action whatever so far as seen and, contrary to Eontgen, no 

 trace of reflection from a steel mirror at a large angle of incidence 

 could be observed. In this latter experiment the mirror was on 

 the side of the photographic plate next to the source of the rays, 

 and not behind it as in Eontgen's method. 



We have, in the short time we have been at work, principally 

 devoted ourselves to finding the source of the rays. For this 

 purpose one of our tubes, made for showing that electricity will 

 not pass through a vacuum, was found to give remarkable results. 

 This tube had the aluminium poles within l mm of each other, and 

 had such a perfect vacuum that sparks generally preferred 10 CU1 in 

 air to passage through the tube. By using potential enough, 

 however, the discharge from an ordinary Euhmkorff! coil could be 

 forced through. The resistance being so high, the discharge was 

 not oscillatory as in ordinary tubes but only went in one direction. 



In this tube we demonstrated conclusively that the main source 

 of the rays was a minute point on the anode nearest to the 

 cathode. At times a minute point of light appeared at this point 

 but not always. 



Added to this source the whole of the anode gave out a few 

 rays. From the cathode no rays whatever came, neither were 

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

 struck it as Eontgen thought. This tube as a source of rays far 

 exceeded all our other collection of Orookes' 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, probably 

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

 cathode rays seem to have anything to do w T ith the Eontgen 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 towards 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. — American Journal of 

 Science, March, 1896. 



NOTE ON "FOCUS TUBES " FOR PRODUCING A'-RAYS. 

 BY R. W. WOOD. 

 The tubes for producing the a?-rays which are furnished with a 

 concave kathode for focussing the kathode rays on the glass, in order 



