THE STORY OF NINETEENTH-CENTURY SCIENCE 



chemicals could be brought forward to prove that the 

 mind harbored no illusion. The photographic film re- 

 corded the things that the eye might see, and ghostty 

 pictures galore soon gave a quietus to the doubts of the 

 most sceptical. Within a month of the announcement 

 of Professor Rontgen's experiments comment upon the 

 " X ray " and the " new photography " had become a 

 part of the current gossip of all Christendom. 



It was but natural that thoughtful minds should have 

 associated this discovery of our boasted latter-day epoch 

 with another discovery that was made in the earliest in- 

 fancy of our century. In the year 1801 Mr. Thomas 

 Wedgwood, of the world-renowned family of potters, 

 and Humphry Davy, the youthful but already famous 

 chemist, made experiments which showed that it was 

 possible to secure the imprint of a translucent body 

 upon a chemically prepared plate by exposure to sunlight. 

 In this way translucent pictures were copied, and skele. 

 tal imprints were secured of such objects as leaves and 

 the wings of insects imprints strikingly similar to the 

 "shadowgraphs" of more opaque objects which we se- 

 cure by means of the " new photography" to-day. But 

 these experimenters little dreamed of the real signifi- 

 cance of their observations. It was forty years before 

 practical photography, which these observations fore- 

 shadowed, was developed and made of any use outside 

 the laboratory. 



It seems strange enough now that imaginative men 

 and Davy surely was such a man should have paused 

 on the very brink of so great a discovery. But to harbor 

 that thought is to misjudge the nature of the human 

 mind. Things that have once been done seem easy; 

 things that have not been done are difficult, though they 



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