31 de Janeiro
ABSTRACTS OF THE PAPERS,
PRINTED IN THE PHILOSOPHICAL TRANSACTIONS
ROYAL SOCIETY OF LONDON
1837 to 1843
Pag. 120, 121
PROCEEDINGS OF THE ROYAL SOCIETY
A paper was read, entitled, « Some account of the Art of Photogenic Drawing, or the Process by wich Natural Objects may be made to delineate themselves without the aid of the Artist’s Pencil ». By H. F. Talbot, Esq., F.R.S.
In this communication the author states, that during the last four or five years he has invented and brought to a considerable degree of perfection, a process for copying the forms of natural objects by means of solar light, wich is received upon paper previously prepared in a particular manner. He observes, that a prior attempt of this kind is recorded in the Journal of the Royal Institution for 1802; by which it appears that the idea was originally suggested by Mr. Wedgwood, and afterwards experimented on by Sir Humphry Davy. These philosophers found, that their principle, though theoretically true, yet failed in practice, on account of certain difficulties; the two principal of which were: first, that the paper could not be rendered sufficiently sensible to receive any impression whatever from the feeble light of a camera obscura; and secondly, that the pictures which were formed by the solar rays could not be preserved, owing to their still continuing to be acted upon by the light.
The author states that his experiments were begun without his being aware of this prior attempt; and that in the course of them he discovered methods of overcoming the two difficulties above related. With respect to the latter; he says, that he has found it possible by a subsequent process, so to fix the images or shadows formed by the solar rays, that they become insensible to light, and consequently admit of being preserved during any lengt of time: as an example of which, he mentions, that he has exposed some of his pictures to the sunshine for the space of an hour, without injury.
With respect to the other point, he states that he has succeeded in discovering a method of preparing the paper which renders it much more sensitive to light than any which had been used previously; and by means of which he finds, that there is no difficulty in fixing the pictures given by the camera obscura and by the solar microscope.
He states that in the summer of 1835 he made a great number of portraits of a house in the country of ancient architecture, several of which were this evening exhibited to the Society.
After some speculations on the possibility of discovering a yet more sensitive paper, the author mentions, that the kind employed by him may be rendered so much so, as to become vivibly affected by the full light of the sun, in the space of half a second.
The rest of this paper contains an account of various other ways in which this method may be employed in practice, according to the kind of object which it is required to copy: also, a brief mention of the great variety of effects resulting from comparatievely small differences in the mode of preparation of the paper: and, of certain anomalies which occur in the process, the cause of which has no hitherto been rendered distinctly manifest.
In conclusion, the author designates this as “a new process, which he offers to the lovers of science and natura.”