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Z\K IDiscovcr^ of IRontgcn: Sonic Details 

 of t\K Bpparatus anD OdGinal jEjperiments,* 



By Hugo Muller (Berlin). 



SLOWLY but uninterruptedly, in general, science proceeds. 

 One stone is laid upon the other, and the building grows 

 more and more ; but from time to time a shock as of light- 

 ning will shake the old, proud scientific construction, including 

 such discoveries as that of the rotation of the earth, of electricity, 

 of the spectral analysis, of the telephone, and so on. Such a 

 discovery was made some weeks since by a German, Prof Rontgen, 

 at Wurzburg. Many journalists have written about this discovery, 

 some with belief, some with scepticism. We are enabled to give 

 our readers illustrations made after Rontgen's descriptions, which 

 prove that he has not claimed too much. The experiments of 

 Rontgen were repeated in the electro-technical laboratory of the 

 Royal Polytechnic at Charlottenburg, Berlin, by Professor Dr. 

 Slaby and his assistant, Klingenberg. I assisted at these experi- 

 ments, and will endeavour to describe them so that anybody 

 possessing the necessary apparatus (which is very costly) will be 

 able to repeat them, and to convince himself of the wonderful 

 invention. The principal apparatus is an evacuated glass globe 

 (or Crookes' tube) of lo to 15 cm. diameter, through which a 

 strong electric current is sent. 



A vacuum is formed in the glass globe, in the first instance, by 

 an air-pump with water, afterwards with mercury, as invented by 

 Sprengel. If the vacuum is not complete, the electric current 

 produces in the evacuated tube the so-called " Geisler " light, 

 which is visible to the human eye. 



As the evacuation (exhaustion) proceeds, the light diminishes, 

 and, at a certain point, it totally disappears. In its place the glass 

 of the tube or globe becomes phosphorescent with a pale green in- 

 termittent light, this phenomenon being produced by the invisible 



* Reprinted by kind permission of the Editor of TAe Amateur Photographer, 

 to whom also we tender our thanks for the use of accompanying block. — Ed. 



