Jafi. 13, 1876] 



NATURE 



205 



new act of partnership, at length discovered (acciden- 

 tally, according to the present account) the action of 

 light upon a film of silver iodide. " Photography was 

 henceforth a fact " — unfortunately, however, at this time 

 his partner died, and Daguerre was left to continue his 

 work alone. 



The history and progress of the nev/ art of Daguerreo- 

 type is then traced, its purchase by the Government I 

 described, and the discover}' of accelerating and fixing \ 

 agents gone into. The editor at this stage reminds us | 

 that the use of sodium hyposulphite was first made ! 

 known by Sir John Herschel, but Mr. Thomson erro- i 

 neously terms this salt a " developing agent." We next \ 

 arrive at that period of the history' when the improvement 

 in lenses effected.by Chevallier enabled the time of expo- 

 sure necessary for a Daguerreotype plate to be reduced, 

 but" even then the sitter had to remain motionless for four 

 or five minutes in full sunshine ! The torments of the 

 unfortunate patient undergoing this ordeal are very gra- 

 phically described. The name of Fox Talbot, who had 

 succeeded in fixing the photographic image on paper 



some years before Daguerre's discovery was made 

 known, does not appear till rather late in this history, 



feS 



Fig. I. — Facsimile of a microscopic despatch used during the sie^e of Paris. 



and then in a position which we cannot but consider as 

 too subordinate, to which effect the editor has added a note. 



The next stage of photographic history brings us to 

 the time of Niepce de Saint- Victor (nephew of the Niepce 

 who was in partnership with Daguerre), who first dis- 

 covered the albumen on glass process. The application 

 of collodion to photography by Legray in France, and 

 Scott Archer in England, brings the art down to its pre- 

 sent state of development, and the author at this stage 

 brings the historical portion of the subject to a conclusion. 

 In the second part of the work the operations and pro- 

 cesses of photogtaphy are dealt with in seven chapters. 

 1 he watchful vigilance which the editor has kept over the 

 interests of British science has here for once failed. The 

 whole credit of the bichromate of potash and gelatine pro- 

 cess — the foundation of all the photographic permanent 

 printing processes — is more than once in the course of 

 the work assigned to Poitevin. " The various processes 



or producing positive carbon prints," writes M. Tissandier 

 on p. 162, "are based on the principle indicated by 

 Alphonse Poitevin in 1 855." We must remind our readers 

 that a patent for the use of bichromate and gelatine in 

 steel engraving was taken out in this countr>' by Fox 

 Talbot in 1852. 



Of the carbon processes that of Swan is described by 

 the author, and the editor adds a brief account of the 

 most recent improvements in this branch of the art 

 adopted by the Autotype company. The last chapter of 

 this part relates to the problems yet awaiting solution, 

 and is chiefly devoted to an account of the attempts which 

 have been made to photograph in natural colours. 



The third and last part of M. Tissandier's book treats 

 of the applications of photography. In the first chapter 

 we have a description of the various heliographic and 



