Photographing the Unseen 



cant in comparison with the brilliant glow which 

 shoots from the cathode, or negative wire. This 

 glow excites brilliant phosphorescence in glass 

 and many substances, and these ' 'cathode rays, " 

 as they are called, were observed and studied by 

 Hertz; and more deeply by his assistant, Pro- 

 fessor Lenard, Lenard having, in 1894, reported 

 that the cathode rays 'would penetrate thin films 

 of aluminum, wood, and other substances, and 

 produce photographic results beyond. It was 

 left, however, for Professor Rontgen to discover 

 that during the discharge quite other rays 

 are set free, which differ greatly from those de- 

 scribed by Lenard as cathode rays. The most 

 marked difference between the two is the fact 

 that Rontgen rays are not deflected by a magnet, 

 indicating a very essential difference, while their 

 range and penetrative power are incomparably 

 greater. In fact, all those qualities which have 

 lent a sensational character to the discovery of 

 Ront gen's rays were mainly absent from those 

 of Lenard, to the end that, although Rontgen 

 has not been working in an entirely new field, he 

 has by common accord been freely granted all 

 the honors of a great discovery. 



Exactly what kind of a force Professor Ront- 

 gen has discovered he does not know. As will 

 be seen below, he declines to call it a new kind 

 of light, or a new form of electricity. He nas 

 given it the name of the X rays. Others speak 

 of it as the Rontgen rays. Thus far its results 

 only, and not its essence, are known. In the 

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