Photographing the Unseen 



he continued, "passed through all the metals 

 tested, with a facility varying, roughly speaking, 

 with the density of the metal. These phe- 

 nomena I have disctissed carefully in my report 

 to the Wiirzburg society, and you will find all the 

 technical results therein stated." He showed a 

 photograph of a small sheet of zinc. This was 

 composed of smaller plates soldered laterally with 

 solders of different metallic proportions. The 

 differing lines of shadow, caused by the difference 

 in the solders, were visible evidence that a new 

 means of detecting flaws and chemical variations 

 in metals had been found. A photograph of a 

 compass showed the needle and dial taken through 

 the closed brass cover. The markings of the 

 dial were in red metallic paint, and thus inter- 

 fered with the rays, and were reproduced. 

 "Since the rays had this great penetrative power, 

 it seemed natural that they should penetrate 

 flesh, and so it proved in photographing the 

 hand, as I showed you." 



A detailed discussion of the characteristics of 

 his rays the professor considered unprofitable 

 and unnecessary. He believes, though, that 

 these mysterious radiations are not light, because 

 their behaviour is essentially different from that 

 of light rays, even those light rays which are 

 themselves invisible. The Rontgen rays cannot 

 be reflected by reflecting surfaces, concentrated 

 by lenses, or refracted or diffracted. They pro- 

 duce photographic action on a sensitive film, but 

 their action is weak as yet, and herein lies the 

 103 



