THE BEGINNINGS OF PHOTOGRAPHY— A CHAPTER IN 

 THE HISTORY OF THE DEVELOPMENT OF PHOTOG- 

 RAPHY WITH THE SALTS OF SILVER/' 



By Maj. Gen. J. Waterhouse, I. A. 



Photograph}" proper, i. c, the art of delineating images of external 

 objects by the agency of light upon chemically prepared sensitive sur- 

 faces, does not seem to have been seriously thought of, still less prac- 

 ticed, before the end of the eighteenth centur}". The publication of 

 Wedgwood and Davy's experiments in 1802 showed not only the 

 possibility of reproducing copies of drawings or paintings on glass, 

 by contact, upon a sensitive surface of paper or leather impregnated 

 with silver nitrate, but also gave the first idea of fixing the images of 

 the camera obscura on such a surface. The results obtained by them 

 were, however, ver}^ imperfect, and photograph}^ did not take anj^ 

 practical shape until the time of Niepce, Daguerre, Reade, and Talbot, 

 between the j^ears 1825 and 1810. But long before Wedgwood's time, 

 and especially during the last two or three decades of the eighteenth 

 century, when the science of chemistry received such rapid develop- 

 ment, considerable attention had been given to the chemical and plw^- 

 ical action of light in changing the appearance of many metallic 

 compounds and organic substances, notably the blackening of animal 

 or vegetal^le tissues by silver nitrate, the darkening of the white sil- 

 ver chloride and other metallic salts, and the darkening or bleaching 

 of many organic dyes and resins, etc. On the other hand, Newton's 

 discovery of the compound nature of white light gave an impetus to 

 the study of the physical nature and of the chemical and optical prop- 

 erties of light and color which in more recent years has had and must 

 continue to have a ver}" strong influence on the further development 

 and progress of photograph}^ Again, Kepler's investigations of the 

 optical principles connected with the projection of images of external 

 objects upon a screen by means of lenses, single or combined, and the 

 camera obscura form the basis of modern ^photographic optics. 



A))out three years ago, when looking up some of the earlier chem- 

 ical writers for inquiries of my own relative to the action of light upon 



« Read before the Royal Photographic Society of Great Britain, April 28, 1908, 

 and reprinted, after revision by tlie author, from The Photographic Journal, London, 

 Vol. XLIII, June, 1903. 



333 



