PHOTOGRAPHY, SCIENTIFIC ASPECTS 



"in pause"; but when thrown on the screen in the 

 moving-picture theatre the whole thing is over in the 

 fraction of a minute. 



THE USES OF PHOTOGRAPHY 



It is safe to say that to-day there is no field of scien- 

 tific research, or the practical conduct of affairs, to which 

 photography has not become an indispensable adjunct. 



Of the immeasurable realms of space, as well as 

 the minute, invisible world about us, the photographic 

 plate has given knowledge that never could have been 

 obtained by the human eye alone. It has unfolded 

 the wonderful world of the spiral nebulae and laid the 

 groundwork for modern conceptions of the universe. 

 It has shed light on the nature of the streaky nebulae 

 and their connection with the great star-stream of the 

 Milky Way, into whose depths it has given us the only 

 means of penetration. It has shown the existence of 

 countless stars, as well as faint members of the solar 

 system, which the human eye aided by the telescope 

 lens has been unable to perceive. It has given much 

 additional insight into the conditions and development 

 of the sun's constituents, and enabled us to measure 

 the motion of the stars toward and away from our 

 own solar system. 



It would be impossible to give any account of the 

 recent triumphs of physical and chemical research 

 without allotting considerable space to the part the 

 camera has played in them. The fact that the sun 

 and fixed stars contain the same elements as does the 



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