

July io, 1890] 



NATURE 



247 



of what was generally regarded as the jubilee of the dis- 

 covery. This celebration was considered by many to 

 have reference to the public disclosure of the Daguerreo- 

 type process, made through the mouth of Arago to the 

 French Academy of Sciences on August lo, 1839. There 

 is no doubt that the introduction of this process marked 

 a distinct epoch in the history of tHe art, and gave a 

 great impetus to its subsequent development. But, while 

 giving full recognition to the value of the discovery of 

 Daguerre, we must not allow the work of his predecessors 

 and contemporaries in the same field to sink into oblivion. 

 After the lapse of half a century we are in a better posi- 

 tion to consider fairly the influence of the work of different 

 investigators upon modern photographic processes. 



I have not the least desire on the present occasion to 

 raise the ghosts of dead controversies. In fact, the history 

 of the discovery of photography is one of those subjects 

 which can be dealt with in various ways, according to the 

 meaning assigned to the term. There is ample scope for 

 the display of what Mr. Herbert Spencer calls the " bias 

 of patriotism." If the word "photography" be inter- 

 preted literally as writing or inscribing by light without 

 any reference to the subsequent permanence of the in- 

 scription, then the person who first intentionally caused 

 a design to be imprinted by light upon a photo-sensitive 

 compound must be regarded as the first photographer. 

 According to Dr. Eder, of Vienna, we must place this 

 experiment to the credit cf Johann Heinrich Schulze, the 

 son of a German tailor, who was born in the Duchy of 

 Madgeburg, in Prussia, in 1687, and who died in 1744, 

 after a life of extraordinary activity as a linguist, theo- 

 logian, physician, and philosopher. In the year 1727, 

 when experimenting on the subject of phosphorescence, 

 Schulze observed that by pouring nitric acid, in which 

 some silver had previously been dissolved, on to chalk, 

 the undissolved earthy residue had acquired the property 

 of darkening on exposure to light. This effect was shown 

 to be due to light, and not to heat. By pasting words 

 cut out in paper on the side of the bottle containing his 

 precipitate, Schulze obtained copies of the letters on the 

 silvered chalk. The German philosopher certainly pro- 

 duced what might be called a temporary photogram. 

 Whatever value is attached to this observation in the 

 development of modern photography, it must be conceded 

 that a considerable advance was made by spreading the 

 sensitive compound over a surface instead of using it in 

 mass. It is hardly necessary to remind you here that 

 such an advance was made by Wedgwood and Davy in 

 1802.^ The impressions produced by these last experi- 

 menters were, unfortunately, of no more permanence than 

 those obtained by Schulze three-quarters of a century 

 before them. 



It will perhaps be safer for the historian of this art to 

 restrict the term photograph to such impressions as are 

 possessed of permanence : I do not, of course, mean 

 absolute permanence, but ordinary durability in the com- 

 mon-sense acceptation of the term. From this point of 

 N iew the first real photographs, i.e. permanent impressions 

 of the camera picture, were obtained on bitumen films by 

 Joseph Niccphore Niepce, of Chalons-sur-Saone, who, 

 after about twenty years' work at the subject, had per- 

 fected his discovery by 1826. Then came the days of 

 silver salts again, when Daguerre, who commenced work 

 in 1824, entered into a partnership with Niepce in 1829, 

 which was brought to a termination by the death of 

 the latter in 1833. The partnership was renewed be- 

 tween Daguerre and Niepce de St. Victor, nephew of 

 the elder Niepce. The method of fixing the camera 

 picture on a film of silver iodide on a silvered copper 

 plate— the process justly associated with the name of 



\ 



' An Account of a Method of Copying Paintings upon Glass, 

 " '• ' ' * "•■ ■ "• af Silv 



_1(J of 



iking Profiles by the Agency of Light' upon Nitrate of'^Silvcr. Invent<;d 

 I'. Wedgwood, Esq. With Observations by H. Davy." Journ. R.I., 

 02, p. 170. 



NO. 1080, VOL. 42] 



Daguerre — was ripe for disclosure by 1838, and was 

 actually made known in 1839. 



The impartial historian of photography who examines 

 critically into the evidence will find that quite indepently 

 of the French pioneers, experiments on the use of silver 

 salts had been going on in this country, and photographs, 

 in the true sense, had been produced almost simul- 

 taneously with the announcement of the Daguerreotype 

 process by two Englishmen whose names are as house- 

 hold words in the ranks of science. I refer to William 

 Henry Fox Talbot and Sir John Herschel. Fox Talbot 

 commenced experimenting with silver salts on paper in 

 1834, and the following year he succeeded in imprinting 

 the camera picture on paper coated with the chloride. 

 In January 1839 some of his "photogenic drawings" — 

 the first " silver prints " ever obtained — were exhibited in 

 this Institution by Michael Faraday. In the same month 

 he communicated his first paper on a photographic pro- 

 cess to the Royal Society, and in the following month he 

 read a second paper before the same Society, giving the 

 method of preparing the sensitive paper and of fixing 

 the prints. The outcome of this work was the " Calo- 

 type " or Talbotype process, which was sufficiently per- 

 fected for portraiture by 1840, and which was fully 

 described in a paper communicated to the Royal Society 

 in 1 84 1. The following year Fox Talbot received the 

 Rumford Medal for his " discoveries and improvements 

 in photography."^ 



Herschel's process consisted in coating a glass plate 

 with silver chloride by subsidence. The details of the 

 method, from Herschel's own notes, have been published 

 by his son. Prof. Alexander Herschel.- By this means 

 the old 40-foot reflecting telescope at Slough was photo- 

 graphed in 1839. By the kindness of Prof. Herschel, and 

 with the sanction of the Science and Art Department, 

 Herschel's original photographs have been sent here for 

 your inspection. The process of coating a plate by 

 allowing a precipitate to settle on it in a uniform film is, 

 however, impracticable, and was not further developed 

 by its illustrious discoverer. We must credit him, how- 

 ever, as being the first to use glass as a substratum. 

 Herschel further discovered the important fact that while 

 the chloride was very insensitive alone, its sensitiveness 

 was greatly increased by washing it with a solution of 

 silver nitrate. It is to Herschel, also, that we are 

 indebted for the use of sodium thiosulphate as a fixing 

 agent, as well as for many other discoveries in connection 

 with photography, which are common matters of history. 



Admitting the impracticability of the method of sub- 

 sidence for producing a sensitive film, it is interesting to 

 trace the subsequent development of the processes in- 

 augurated about the year 1839. The first of photographic 

 methods — the bitumen process of Niepce — survives at 

 the present time, and is the basis of some of the most 

 important of modern photo-mechanical printing processes. 

 [Specimens illustrating photo-etching from Messrs. Water- 

 low and Sons exhibited.] The Daguerreotype process is 

 now obsolete. As it left the hands of its inventor it was 

 unsuited for portraiture, on account of the long exposure 

 required. It is evident, moreover, that a picture on an 

 opaque metallic plate is incapable of reproduction by 

 printing through, so that in this respect the Talbotype 

 possessed distinct advantages. This is one of the most 

 important points in Fox Talbot's contributions to photo- 

 graphy. He was the first to produce a transparent paper 

 negative from which any number of positives could be 

 obtained by printing through. The silver print of modern 

 times is the lineal descendant of the Talbotype print. 

 After forty years' use of glass as a substratum, we are 

 going back to Fox Talbot's plan, and" using thin flexible 



' For these and olher details relating to Fox Talbot's work, necessarily 

 excluded for want of time, I am indebted to his son, Mr. C. H. Talbot, of 

 Lacock Abbey. 



'' Photog. Journ. and Trans. Photog. Soc, Juue 15, 1872. 



