136 HISTORICAL NOTE. 



CHAPTER XL 



ON THE PROCESS OF DAGUERREOTYPE, AND ITS APPLICATION TO TAKING PORTRAITS 



FROM THE LIFE. 



Historical Note. This chapter contains the first published description of the process 

 of taking Daguerreotype portraits. Of late, both in America and in Europe, this art 

 has been much cultivated and improved ; it now forms a branch of industrial occupa- 

 tion. That it was possible by photogenic processes, such as the Daguerreotype, to ob- 

 tain likenesses from the life, was first announced by the author of this volume in a note 

 to the editors of the Philosophical Magazine, dated March 31st, 1840, as may be seen 

 in that Journal, June, 1840, page 535. The first Daguerreotype portraits to which al- 

 lusion is made in the following chapter (523) were produced in 1839, almost immedi- 

 ately after M. DAGUERRE'S discovery was known in America. 



It may farther be remarked, that of those spectral images which have excited so much 

 attention of late in Europe, under the name of MOSER'S images, an account is here 

 given, and given in connexion with the explanation of the Daguerreotype (527-544). 

 A successful attempt was made in Germany, in 1842, to appropriate the discovery of 

 these singular phenomena by the natural philosopher whose name now stands in con- 

 nexion with them. 



Of these two incidents in the science of photography, some account may be seen in 

 the Edinburgh Review for January, 1843. In that work, the discovery of the art of 

 taking Daguerreotype portraits, and the first observations on spectral images, are attribu- 

 ted to their true source, the author of this book.* 



* " He was the first, we believe, who, under the brilliant summer sun of New- York, took portraits with the Daguerreotype. 

 This branch of photography seems not to have been regarded as a possible application of DAGUERRE'S invention, and no notice 

 is taken of it in the reports made to the legislative bodies of France. We have been told that DAGOERRE had not, at that period, 

 taken any portraits ; and when we consider the period of time, twenty or twenty-five minutes, which was then deemed ne- 

 cessary to get a Daguerreotype landscape, we do not wonder at the observation of a French author, who describes the taking 

 of portraits as toujours un terrain un peu fabuleux pour le Daguerreotype. DAGDERRE, however, and his countryman, M. CLAUDET, 

 have nobly earned the reputation of having perfected this branch of the art. 



" It has been long known that if we write upon a piece of glass with a pencil of soapstone or agalmatolite, the written let- 

 ters, though wholly invisible, may be read by simply breathing upon the glass ; and this even though the surface has been 

 well cleaned after the letters had been written. Dr. DRAPER observed that if a piece of metal, a shilling, for example, or even 

 a wafer, is laid upon a cool surface of glass or polished metal, and the glass or metal breathed upon, then, if the shilling is 

 tossed from the surface, and the vapour dried up spontaneously, a spectral image of the shilling will be seen by breathing 

 again upon the surface, the vapour depositing itself in a different manner upon the part previously protected by the shilling. 

 More recently, Professor DRAPER has shown that this spectral image could be revived during a period of several months of 

 the cold weather in the winter of 1840-41 ; but he has stated that he cannot find the reason of this result, though he regards 

 it as analogous to the deposition of mercurial vapour in the Daguerreotype. We have often repeated this interesting exper- 

 iment by keeping the protecting body, the shilling or wafer, at a distance from the glass or metallic surface, or by putting it 

 under a watch-glass ; and we found that the result was always the same (even after cleaning the surface with soft leather), 

 so that change of temperature, or any pressure upon the glass surface, were excluded as causes of the phenomena." (Ex- 

 tract from the Edinburgh Review for January, 1843, p. 339.) 



