xiv Introduction 



This was practically the commencement of photog- 

 raphy, and its invention entitles Daguerre to rank with 

 the foremost inventors of the nineteenth century. 



At the same time that Daguerre was pursuing his 

 researches in France an Englishman, named Fox Talbot, 

 was working along somewhat similar lines in England, 

 and in 1841 he patented what he called the calotype 

 process. 



It is unnecessary to go into a description here of 

 these two processes. Suffice it to say that the image 

 was made in the former on copper, plated with silver, 

 while in the latter it was made upon paper. This latter 

 was really a negative, for on it the qualities of the 

 image were reversed as we now have them on our dry 

 plates. The correct picture, in black and white, was 

 obtained by oiling the original, which caused it to 

 become transparent, and then printing through it on to 

 another piece of sensitized paper, exactly as we do at 

 the present time. 



The collodion process of glass plates was the next 

 great step in advancement. It was invented by an 

 Englishman named Scott Archer, and was first given 

 to the world in 1851. In a few years it had so far 

 displaced both the calotype and the daguerreotype 

 that it reigned supreme from 1855 to 1880. 



Up to about 1853 a photograph was considered noth- 

 ing short of a curiosity, but with the introduction and 

 perfection of the collodion process photography be- 

 came an almost popular pursuit. In the collodion 

 process, as introduced by Archer, it was absolutely 

 necessary that the glass plates, coated with collodion 

 containing iodide and nitrate of silver, should be ex- 



