ART AND SCIENCE CLAIMS OF PHOTOGRAPHY. 



39 



port understood. Photography has illustrated the general history 

 of science in an especial manner. The early explorers had no 

 other source of reliance but the results of tentative experiment. 

 "When a few facts were established, chemistry was enabled to offer 

 a valuable helping hand, and photography has well repaid the loan 

 by bringing to light chemical laws before only dimly dreamed of. 

 The science of photography treats of that property that light 

 possesses of changing the colour of objects, so that it may be used 

 for pictorial purposes. 



The progress that had been made towards producing photographs 

 in natural colours was then noticed, and attention drawn to the 

 researches and experiments of M. Becquerel, M. Poitevin, and Mr. 

 W. Simpson, in all of which one fact was worthy of notice, — 

 that violet sub-chloride of silver was recognised as the common 

 starting-point. 



The experiments of M. Duces du Hauron and M. Chas. Cros 

 were then referred to. Tliese gentlemen, instead of endeavouring 

 to reproduce on one and the same surface all the natural colours 

 indistinctly, sought to analyse and separate them, so as to obtain 

 three impressions corresponding to the three primitive colours — 

 red, yellow, and blue ; and these three monochrome results, pre- 

 senting all the gradations of tint which photography re-produces 

 so accurately, being combined by some system of synthesis, are 

 blended together, and yield all the other colours, inasmuch as the 

 three together contain all the elements of the spectrum. 



With regard to the question of permanence, which happily had 

 been solved by science, durability unquestionably was an impor- 

 tant merit ; but it was to be prized upon grounds entirely distinct 

 from an abstract admiration of art. The more durable a work of 

 art was, the more durable it was as a possession ; but considered 

 simply as a work of art, it was neither better nor worse than that 

 which possessed the quality in a minor degree. 



The photo-relief printing processes of Mr. Woobury and M. 

 Obemetter were then described, together with that of HeiT Albert, 

 the most perfect lately presented to the public (an admirable illus- 

 tration of the process being handed round for inspection). 



The scientific claims of photography were then closed with a 

 notice of the researches of Professor Mach of Gratz, who by its 

 means was enabled to make his experiments on the effect upon 

 the retina of masses of light distributed over certain spaces, the 



