The Evolution of Photography. Werge John

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СКАЧАТЬ by means of a camera-obscura have been found to be too faint to produce, in any moderate time, an effect upon the nitrate of silver. To copy these images was the first object of Mr. Wedgwood, in his researches on the subject, and for this purpose he first used the nitrate of silver, which was mentioned to him by a friend, as a substance very sensible to the influence of light; but all his numerous experiments as to their primary end proved unsuccessful.”

      From the foregoing extracts from the first lecture on photography that ever was delivered or published, it will be seen that those two eminent philosophers and experimentalists despaired of obtaining pictures in the camera-obscura, and of rendering the pictures obtained by superposition, or cast shadows, in any degree permanent, and that they were utterly ignorant and destitute of any fixing agents. No wonder, then, that all further attempts to pursue these experiments should, for a time, be abandoned in England. Although Thomas Wedgwood’s discoveries were not published until 1802, he obtained his first results in 1791, and does not appear to have made any appreciable advance during the remainder of his life. He was born in 1771, and died in 1805. Sir Humphry Davy was born at Penzance 1778, and died at Geneva in 1828, so that neither of them lived to see the realization of their hopes.

      From the time that Wedgwood and Davy relinquished their investigation, the subject appears to have lain dormant until 1814, when Joseph Nicéphore Niépce, of Chalons-sur-Saône, commenced a series of experiments with various resins, with the object of securing or retaining in a permanent state the pictures produced in the camera-obscura, and in 1824, L. J. M. Daguerre turned his attention to the same subject. These two investigators appear to have carried on their experiments in different ways, and in total ignorance of the existence and pursuits of the other, until the year 1826, when they accidentally became acquainted with each other and the nature of their investigations. Their introduction and reciprocal admiration did not, however, induce them to exchange their ideas, or reveal the extent of their success in the researches on which they were occupied, and which both were pursuing so secretly and guardedly. They each preserved a marked reticence on the subject for a considerable time, and it was not until a deed of partnership was executed between them that they confided their hopes and fears, their failures with this substance, and their prospects of success with that; and even after the execution of the deed of partnership they seem to have jealously withheld as much of their knowledge as they decently could under the circumstances.

      Towards the close of 1827 M. Niépce visited England, and we receive the first intimation of his success in the production of light-drawn pictures from a note addressed to Mr. Bauer, of Kew. It is rather curious and flattering to find that the earliest intimation of the Frenchman’s success is given in England. The note which M. Niépce wrote to Mr. Bauer is in French, but the following is a translation of the interesting announcement:—“Kew, 19th November, 1827. Sir,—When I left France to reside here, I was engaged in researches on the way to retain the image of objects by the action of light. I have obtained some results which make me eager to proceed.... Nicéphore Niépce.” This is the first recorded announcement of his partial success.

      In the following December he communicated with the Royal Society of London, and showed several pictures on metal plates. Most of these pictures were specimens of his successful experiments with various resins, and the subjects were rendered visible to the extent which the light had assisted in hardening portions of the resin-covered plates. Some were etchings, and had been subjected to the action of acid after the design had been impressed by the action of light. Several of these specimens, I believe, are still extant, and may be seen on application to the proper official at the British Museum. M. Niépce named these results of his researches Heliography, and Mr. Robert Hunt gives their number, and a description of each subject, in his work entitled, “Researches on Light.” M. Niépce met with some disappointment in England on account of the Royal Society refusing to receive his communication as a secret, and he returned to France rather hurriedly. In a letter dated “Chalons-sur-Saône, 1st March, 1828,” he says, “We arrived here 26th February”; and, in a letter written by Daguerre, February 3rd, 1828, we find that savant consoling his brother experimentalist for his lack of encouragement in England.

      In December, 1829, the two French investigators joined issue by executing a deed of co-partnery, in which they agreed to prosecute their researches in future in mutual confidence and for their joint advantage; but their interchange of thought and experience does not appear to have been of much value or advantage to the other; for an examination of the correspondence between MM. Niépce and Daguerre tends to show that the one somewhat annoyed the other by sticking to his resins, and the other one by recommending the use of iodine. M. Niépce somewhat ungraciously expresses regret at having wasted so much time in experimenting with iodine at M. Daguerre’s suggestion, but ultimate results fully justified Daguerre’s recommendation, and proved that he was then on the right track, while M. Niépce’s experiments with resins, asphaltum, and other substances terminated in nothing but tedious manipulations, lengthy exposures, and unsatisfactory results. To M. Niépce, most unquestionably, is due the honour of having produced the first permanent sun-pictures, for we have seen that those obtained by Wedgwood and Davy were as fleeting as a shadow, while those exhibited by M. Niépce in 1827 are still in their original condition, and, imperfect as they are, they are likely to retain their permanency for ever. Their fault lay in neither possessing beauty nor commercial applicability.

      As M. Niépce died at Chalons-sur-Saône in 1833, and does not appear to have improved his process much, if any, after entering into partnership with M. Daguerre, and as I may not have occasion to allude to him or his researches again, I think this will be the most fitting place to give a brief description of his process, and his share in the labours of bringing up the wonderful baby of science, afterwards named Photography, to a safe and ineffaceable period of its existence.

      The Heliographic process of M. Niépce consists of a solution of asphaltum, bitumen of Judea, being spread on metal or glass plates, submitted to the action of light either by superposition or in the camera, and the unaffected parts dissolved away afterwards by means of a suitable solvent. But, in case any student of photography should like to produce one of the first form of permanent sun-pictures, I shall give here the details of M. Niépce’s own modus operandi for preparing the solution of bitumen and coating the plate:—

      “I about half fill a wine-glass with this pulverised bitumen; I pour upon it, drop by drop, the essential oil of lavender until the bitumen is completely saturated. I afterwards add as much more of the essential oil as causes the whole to stand about three lines above the mixture, which is then covered and submitted to a gentle heat until the essential oil is fully impregnated with the colouring matter of the bitumen. If this varnish is not of the required consistency, it is to be allowed to evaporate slowly, without heat, in a shallow dish, care being taken to protect it from moisture, by which it is injured and at last decomposed. In winter, or in rainy weather, the precaution is doubly necessary. A tablet of plated silver, or well cleaned and warm glass, is to be highly polished, on which a thin coating of the varnish is to be applied cold, with a light roll of very soft skin; this will impart to it a fine vermilion colour, and cover it with a very thin and equal coating. The plate is then placed upon heated iron, which is wrapped round with several folds of paper, from which, by this method, all moisture had been previously expelled. When the varnish has ceased to simmer, the plate is withdrawn from the heat, and left to cool and dry in a gentle temperature, and protected from a damp atmosphere. In this part of the operation a light disc of metal, with a handle in the centre, should be held before the mouth, in order to condense the moisture of the breath.”

      In the foregoing description it will be observed how much importance M. Niépce attached to the necessity of protecting the solution and prepared plate from moisture, and that no precautions are given concerning the effect of white light. It must be remembered, however, that the material employed was very insensitive, requiring many hours of exposure either in the camera or under a print or drawing placed in contact with the prepared surface, and consequently such precaution might not have been deemed necessary. Probably M. Niépce worked in a subdued light, but there can be no doubt about the necessity of conducting both the foregoing operations in yellow light. Had M. Niépce performed his СКАЧАТЬ