November 6, 1919] 



NATURE 



251 



PROGRESS OF PHOTOGRAPHY. 



By Chapman Jones. 



^pO most, people fifty years ago, photography 

 -L was represented by the "carte-de-visite " 

 which they exchanged with their friends, and 

 ;i few " views " which they bought now and 

 •hen as mementoes. Some who were rather 

 i)etter-to-do preferred the larger " cabinets " which 

 had been fashionable for two or three years. But 

 there were also, as there had been for the previous 

 thirty years or more, an increasing number of 

 those who were really interested in the art and 

 the science of photography. The Royal Photo- 

 graphic Society, then the Photographic Society of 

 London, was sixteen years old, and there had 

 :jeen journals devoted to photography for about 

 as long. The rapid rectilinear lens, which has 

 enjoyed a greater popularity than any other lens, 

 had just been introduced. The carbon process 

 had already been practised commercially, but in 

 that very year it received its final simplification 

 l»v the elimination of the use of a cement to hold 

 the exposed tissue on to its support during 

 development. Large photographs had been made, 

 one, 12 ft. by 7 ft., having been recorded in 1868. 

 Photography in natural colours had had its history 

 written, the principles of three-colour photo- 

 graphy were understood, the nature of the 

 developable image had been much discussed, and 

 an electrical theory had been proposed. Actino- 

 meters had been devised. The kinematograph 

 was represented by the zoetrope, or "wheel of 

 life," a mere toy. 



Thus it is obvious that when Nature first saw 

 the light photography had made very consider- 

 able progress, but its applications were hampered 

 bv its limitations. There was no plate sensi- 

 tive enough for a photographic zoetrope, and the 

 three-colour method of colour photography was 

 n(jt practical, because the plates available were 

 insensitive to red and nearly insensitive to green. 

 But the keys to the removal of these two great 

 barriers to progress were soon to be found. 

 Vogel's fundamental discovery that silver haloids 

 might be made sensitive to red and to green by 

 treating them with certain colouring matters was 

 made within four years, and within eight years, 

 during which gelatine had been coming to the 

 front as a medium to replace collodion, Bennett 

 found that by keeping gelatine emulsion warm 

 for a few days the general sensitiveness of the 

 plates coated with it was increased very many 

 times. It remained, of course, to develop the possi- 

 bilities thus demonstrated, and, equally of course, 

 they were developed. During the 'seventies there 

 were other notable matters. Printing in platinum 

 was introduced, the replacement of glass by films 

 received attention, and the photographic zoetrope 

 became an accomplished fact in the work of 

 Mr. Muybridge, of California. 



In the 'eighties hand-cameras began to appear, 

 isochromatic plates (that is, plates sensitised for 

 green) were commercially produced, films were 

 NO. 2610, VOL. 104] 



made practical, plates and films were coated by 

 machines instead of by hand, and developing 

 agents, which had hitherto been restricted to two 

 or three, began to increase in number. 



In the next decade, the 'nineties, Carl Zeiss 

 issued the first anastigmat, which was soon fol- 

 lowed by the products of other firms, and the 

 mechanical, photographic, and optical difficulties 

 of kinematography were largely overcome. 

 Many new developing agents were introduced, and 

 the chemical constitution apparently necessary to 

 confer the power of development was elucidated. 



In the early years of the present century much 

 superior colour sensitisers Tor gelatine plates were 

 found, and panchromatic plates became practically 

 a new power in dealing with colour. The auto- 

 chrome plate provided the first commercially prac- 

 tical method of photography in natural colours 

 on a single plate and by one series of operations. 



This brief sketch of some of the chief items of 

 the history of photography for the period under 

 review is necessarily very incomplete, but it gives 

 landmarks that may help to picture the general 

 progress. The applications to scientific and pic- 

 torial work, as well as to matters of immediate 

 commercial importance, followed close upon each 

 step that increased the scope of photographic 

 methods, until in many cases these took the first 

 place instead of a very subordinate position. We 

 have examples of this in astronomy, in surveying, 

 and especially in photo-engraving and block- 

 making, for in this last case the hand methods 

 have been rendered commercially obsolete. With 

 the increase of facility the popularity of photo- 

 graphy increased until now one regards any 

 person who can say that he has never taken a 

 photograph as something akin to a person who 

 is unable to write. 



The Editor asks me to say something as to the 

 "promise of future advance." Photography in its 

 essence is a pictorial method of recording, and 

 may therefore be fitly associated with writing, 

 though photography has the great advantage of 

 being automatic. Besides this it has so many ad- 

 vantages that it will form a necessary part of the 

 training of every well-educated person. Whether 

 it will be a college or a secondary-school subject 

 the educationists must decide, but it will form 

 a necessary adjunct to the study of almost all 

 college subjects. In the professional and com- 

 mercial world its importance will be increasingly 

 recognised as a means of rapidly getting unbiased 

 records. The kinematograph is a photographic 

 method of recording movement whether slow or 

 rapid, and will therefore be increasingly appre- 

 ciated both for scientific purposes and as a means 

 of education. 



As to pure photography — that is, the study of 

 photography itself — we do not know what change 

 takes place in silver salts when they are rendered 

 developable. Of late this matter seems to have 



