334 PROCEEDINGS OF THE OHIO ACADEMY OF SCIENCE. 



eses, which at present seem incompatible with each other. The 

 great reconciHng theory is yet to come. 



Another great group of researches is that chiefly inspired 

 by the discovery of Roentgen, which has proven as varied and 

 complex in its ramifications, as the other one was simple and 

 direct, and which, starting as the other did in phenomena of 

 radiation, has found its most interesting field in the nature of 

 matter and the structure of the atom. This series really begins 

 before i860, with the work done by several investigators on 

 electrical discharge through highly exhausted tubes — Crookes' 

 tubes, as they were called in England. It was in 1895 that 

 William Conrad Roentgen, while experimenting at Wiirzburg 

 with a tube of this type, perceived the lighting up of a fluorescent 

 plate which lay at a distance of two or three metres from his 

 apparatus, and thus, partly by accident (such accidents as are 

 always happening to men who can make use of them), came 

 upon the radiations which bear his name. His brief paper, an 

 admirable example of scientific presentation, represented work 

 so careful and precise, that for nearly ten years little was added 

 to our real knowledge of the X-rays or to the contents of his 

 first article, by the host of workers who threw themselves at 

 once upon the new phenomena. 



Roentgen showed that these new rays were generated where 

 cathode rays strike some solid body, and that they spread from 

 this area of impact as from a source. What was their nature? 

 Not electrified particles like the cathode rays, because they were 

 not afljected by an electric or magnetic field, not light-waves, for 

 they showed under the ordinary tests, neither reflection, refrac- 

 tion or polarization. It was suggested by Bragg and others 

 that they might be streams of flying particles, diff^erent from 

 the cathode rays in that they were neutral doublets, or particles 

 carrying no electric charge. Roentgen guessed that they might 

 be longitudinal ether-waves ; Schuster showed that they might 

 be transverse waves like light-waves, if they were only short 

 enough, and it seemed indeed probable that some sort of elec- 

 tromagnetic disturbance, akin to light, might be set up in the 

 region, bombarded by the cathode rays, from which the X-rays 



