NATURAL DAGUERREOTYPING.

From Chambers's Edinburgh Journal.

THE British journals have as yet taken no notice, that we are aware of, of some very curious discoveries respecting light lately made by Dr. Moser of Königsberg. By accident, in a great measure, we have obtained some information on the subject, which we shall now lay before our readers, confident that it will be read with considerable interest even by those but slightly acquainted with science.

duced by being again breathed upon or subjected to other vapor, and this over and over again, as often as may be desired.

An account of Dr. Müser's discovery was given a few months ago in the Paris Academy of Sciences, and had the effect of calling from M. Breguet, the celebrated watchmaker of that city, a remark highly favorable to the presumption that it is true. M. Breguet stated that he had frequently observed, upon the polished inner surface of the gold cases of his flat watches, the name of his house plainly and legibly marked, the impression having been received from the engraved letters of the covering of the works, which did not touch the case.*

Möser infers from his observations that there is LATENT LIGHT-a bold idea, which, if it becomes an established truth in science, must immortalize his name. He conceives that light enters into and resides in bodies, or is, as it were, absorbed in them. and may yet, after remaining in them many years, be capable of exhibiting its action. He calls this light proper to bodies, and shows reasons for distinguishing it from both phosphorescence and the light of those rays of which the retina is not sensible. He says it is in all its effects the same as ordinary light. In two plates exposed to each other, that the one may catch an image from the other, nearness is necessary, because otherwise the rays would diverge, and produce a confused image. How strange to think of a divergence of rays from a substance placed in what our senses would call absolute darkness; for example, between the works and case of a watch!‡

Dr. Moser observes, that if a flat seal or piece of black horn, having figures engraved upon it, be placed below a smooth and polished silver plate, and allowed to remain there for ten minutes, the silver will become charged with a faint picture of the figures engraved upon the seal or piece of horn, which will be rendered visible by the plate being exposed to the vapor of water, or any other fluid, or even by being breathed upon, and will become permanent if the vapor of mercury is used. This surprising result will at once lead the mind to the photographic process, in which, by the action of a strong light, either original or reflected, the images of objects become impressed upon a surface of paper previously washed in a solution of nitrate of silver, or a metallic plate prepared with iodine. But a remarkable difference exists; the silver plate in Dr. Mōser's experiment is presented in the dark, and there receives the impression of the object, without, as we would suppose, the agency of light. The experiment has even been made in a dark room at midnight with perfect success. It is also remarable, that any polished surface These phenomena are not curious only for will do as well as a silver plate-glass, for in- their reference to the novel idea of latent light, stance, or the smooth leather-cover of a book. but as an addition to the wonders of that perIt appears that, to produce the effect, the object haps most wonderful of all modern inventions, must not be far distant from the smooth surface; the photographic and Daguerreotype processes. the nearer it is, the better is the impression pro- What we have hitherto seen of this process is duced. When the vapor of mercury is used, a the production of an image under the influence permanent image is produced, by an union of of a powerful light: the experiments of Möser the mercury with the silver; when other vapors give an image by the agency of a degree of are used, the image quickly vanishes. But per-light below the power of our senses to apprehaps the most surprising thing of all is, that after the image has vanished, it can be repro

In a letter written by him to Sir David Brewster-which we have seen-he states that he has found the following invariably to succeed. He places a small camera obscura, furnished with a lens of very small aperture" under the moon in any of her stages, and makes her image fall upon a plate of iodised silver, which has been previously exposed to certain vapors noted below. The moon having passed over the plate, he subjects the plate to the vapor of mercury, and obtains a very clear representation of her path.-It may here be remarked, that there is no necessity for supposing Möser's experiments to be fallacious because an attempt to repeat them may fail. While it is proper, of course, to be guarded against both voluntary and involuntary deception, there can be no doubt that nice experiments of this nature often fail, or all but fail, at first, with others than the discoverers, and yet are found to be true phenomena after all. Such was the case with Mr. Fox Talbot's experiments in photography, which some of the most ingenious practical men of science in the country vainly, for some time, attempted to imitate.

hend; and which we, therefore, for want of a
better term, call latent light. This is a remark-
able extension, indeed, of what we not long ago
knew of the powers of light: we now know that
it will act as a medium through which the image
of one object may be impressed on another, the
impression possessing durability in proportion
to the conditions of the impressed surface; and,
more than this, capable of being reproduced after
it has vanished, and that several times over, Nor
*Athenæum Report, September 10, 1842.
† Letter of Dr. Möser, MS.

The idea of latent light corresponds with an opinion of Newton, that light entered the surface There are other phenomena tending to the same of charcoal, and never was brought out again. conclusion, as that nitrous acid gas. in a glass tube, on being exposed to heat, changes from a transpatient under inflammation, everted from a cup with rent yellow to an opaque red. The blood of a paflower relieved upon the dark ground of the clot. a green flower, presents vermilion images of the And, to preclude all doubt as to the character of these images, we are assured by a medical friend that he has produced them by green coloring on the outside of a glass cup.

ing longer than usual, in consequence of the retina being longer impressed. In some cases, he had been enabled to tear off the mask, and fill up these blank faces with individual likenesses." These remarks of the British philosophers have since been found to coincide with views entertained by Dr. Möser, and which he has expressed in a paper published at Berlin. That the impressions on the retina are photographic processes, is, we should say, by no

is even this all. The Daguerreotype process, | objects flitted before his eyes. He could not till a very recent period, did, like Dr. Müser's distinguish the whitest face in the company experiments, require what may be called a con- from the darkest. Here was a picture continusiderable time to produce its effects; that is to say, it required a few seconds at least, and only still objects could be taken with accuracy. But last year, by the application of electricity, M. Daguerre made his plates so sensitive, that less than a second became necessary to produce the image. Indeed, so small a space of time was required, that no mechanical arrangement could be contrived to submit the plate instantaneously enough; the consequence of which was, that one part was overdone before the rest was sub-means unlikely. Many phenomena, long before mitted, and it was found necessary to take means to dull or lessen the sensitiveness of the plates.* Possibly, the application of electricity would make a much less space of time necessary for even latent light to produce images. The Daguerreotype process is evidently only in its infancy. Within the last few months, Sir John Herschel has been experimenting with paper surfaces prepared in two different ways, by one of which he produces impressions which may be brought up from faintness to distinctness by repeated washings, while by the other he creates positive pictures, which fade in a few hours, leaving the paper capable of receiving other impressions.t

the world, perfectly harmonise with such an idea. The sixth of a moment, is, we believe, the space of time which these impressions remain in an ordinary state of health; hence, we may remind unscientific readers, such phenomena as that of a lighted stick making a fiery arc when waved quickly to and fro. The eye, then, may be said to be, in its ordinary state, a plate or speculum prepared to receive, and retain for that definite portion of time, any image thrown upon it. Amongst relative phenomena, the mind very quickly lights upon a well-known one recorded by Dr. Darwin: "I covered a paper about four inches square with yellow, and with a pen filled with a blue color, wrote upon In a conversation on Dr. Möser's experiments, the middle of it the word BANKS in capitals; which took place at the meeting of the British and sitting with my back to the sun, fixed my Association at Manchester, Sir John Herschel eyes for a minute exactly upon the centre of the called particular attention to the reproduceabili- letter N in the word. After shutting my eyes, ty of the pictures, and confirmed the fact by and shading them somewhat with my hand, the drawing from his pocket one of his own pictures, word was distinctly seen in the spectrum in yelwhich he said was then invisible, but might be low colors on a blue ground; and then, on openmade visible by being placed over the vapor of ing my eyes. on a yellowish wall at twenty feet muriatic gas. After a time, he said the image distance, the magnified name of BANKS apwould again vanish, but a reapplication of the peared on the wall written in golden character s." gas would bring it again into sight. He ex- Dr. Abercromby records a similar instance: "A plained that the paper had been washed in a friend of mine had been, one day, looking incertain vegetable solution, which made it sus- tensely at a small print of the Virgin and Child, ceptible of such pictures. He also adverted to and had sat bending over it for some time. On the remarkable fact, that the muriatic gas is per- raising his head, he was startled by perceiving fectly colorless. He then added, "Might not at the further end of the apartment a female the retina itself be affected in a somewhat simi- figure of the size of life, with a child in her arms. lar manner? The impressions made upon it The first feeling of surprise having subsided, he were gone in a moment. Might not those im- instantly traced the source of the illusion, and pressions on the retina be produced by a sort of remarked that the figure corresponded exactly photographic apparatus? The number of ques- with that which he had contemplated in the tions arising on this topic," he said, "were like-print, being what painters call a kit-cat figure, ly to render it a most electrifying topic among in which the lower parts of the body are not rephilosophers." Sir David Brewster considered presented. The illusion continued distinct for the remark of Sir John Herschel, as "having an important bearing on the philosophy of the senses, The moment it was mentioned in the hearing of any one acquainted with the physiological action of the retina, he would see a crowd of facts referable to it. He should mention one fact which appeared to be explained by it. After being present at a few of the meetings of the Association, where there had been so many white faces, a mass of white faces had at length become impressed on his retina. Each face had three black spots on it, two for the eyes and one for the mouth. For two days, these

Athenæum Report, July 17, 1841.

† Letter of Sir John Herschel, Athenæum, August 20, 1842.

about two minutes."* In Dr. Darwin's case, there was, we believe, only the ordinary action of the eye inexhibiting the spectrum of the acci dental colors: in such instances as that recorded by Dr. Abercromby, and described by Sir David Brewster, there is probably some extraordinary phenomena, by which the impression, a simple image, is rendered permanent; we can easily conceive it to be some phenomena in organic pathology analogous to the washing of a plate with a solution.

But is it upon the retina, or the retina alone, that the impression lingers? "In regard to a ocular spectra," says Dr. Abercromby, "another

* Abercromby's Inquiries concerning the Intellectual Powers, p. 65.

he

fact of a very singular nature appears to have they are objects-things producing a clear phobeen first observed by Sir Isaac Newton; name-tographic image, so to speak, on the brain. ly, that when he produced a spectrum of the sun Men in a partially diseased or infirm condition by looking at it with the right eye, the left being lose the recollection of words, or of names, but covered, upon uncovering the left, and looking remember things and persons. They know the upon a white ground, aspectrum of the sun friend they meet, but they caanot pronounce his was seen with it also. He likewise acquired name. Dr. Abercromby tells of a gentleman the power of recalling the spectra after they had who "could not be made to understand the ceased, when he went into the dark, and directed | name of an object, if it was spoken to him, but his mind intensely, as when a man looks earn-understood it perfectly when it was written. His estly to see a thing which is difficult to be seen.' | mental faculties were so entire, that he was enBy repeating these experiments frequently, such gaged in an extensive agricultural concerns, and an effect was produced upon his eyes, that for he managed them with perfect correctness by some months after,' he says, 'the spectrum of means of a remarkable contrivance. He kept the sun begun to return, as often as I began to before him, in the room where he transacted meditate upon the phenomena, even though I business, a list of the words which were most lay in bed at midnight with my curtains drawn."" apt to occur in his intercourse with his workmen. Does not this seem to imply that, if an actual When any of them wished to communicate with impression of any kind is made, it must be upon him upon any subject, he first heard what the something beyond the retina, something com- workman had to say, but without understandmanding both the outlets where the retina areing him further than simply to catch the words. placed; upon that internal nervous substance, in He then turned to the words in the writshort, which forms the medium or organism of ten list, and whenever they met his eye, mind itself? understood them perfectly." Here, clearly, a There are certainly many psychological certain mental power was wanting. But the phenomena which seem to bear a curious ana-power of receiving a direct impression from an logy to these image-making properties of light. object remained sound, and was used. What For instance, "the distinct recollection of a fact was this but having to repeat every time those is generally in proportion to the intensity with messages between objects in the external world which it has been contemplated." Suppose and the inner powers of mind, which usually beattention to be a greater than usual develop-come unnecessary in a mature intellect, from so ment of electric action in the brain, how strange- much coming to be fixed and understood? It ly akin seem the recent experiments of Da- was like Herschel's photographic paper, or guerre! When attention is languid, or when Möser's plates, where some common vapor was one is in a state of reverie, something is said by used. Old men generally remember recent a neighbor: you are not conscious of more than events least perfectly. This may be simply that some one has spoken; but in a few seconds, owing to the images in early life having been or perhaps minutes, by an effort, the words are impressed on what was in a more fit state to rerecalled. May not this be simply an electric ceive them, or having been better secured after evolution upon some impressible medium within, they were impressed. A silver plate bearing a before the photographic impression had faded, good photographic image, of three years' standcatching up its shrinking tints? Newton coulding, fixed with the fumes of mercury, or nitrate recall the spectra by intensely looking for them, or meditating upon them; so, by an effort of the mind, do we recall to memory a fact which we once knew, but which has been forgotten. To write down any thing we may wish to remember, or to learn it from print or writing, is ac- There are instances of temporary loss of meknowledged to be the most ready means of ac- mory in consequence of external injuries to the quiring it by heart. A comedian, accustomed nervous system, and we chance to be able to adto study his parts deliberately, and who remem-vert to a remarkable example heretofore unrebered them afterwards without effort, had on one corded. A boy of uncommon talents, who has occasion to study one very hurriedly. This part since attained high civil employment in India, immediately after disappeared from his mind. was boarded, during his attendance at the uni"When questioned respecting the mental pro- versity, in the house of a medical gentleman, cess which he employed the first time he per- who took charge of a few other youths of about formed this part, he said that he lost sight en- the same age. Towards the conclusion of a sestirely of the audience, and seemed to have noth- sion, during which he had studied very hard, and ing before him but the pages of the book from the night before he was to deliver a prize essay which he had learnt it, and that if any thing had to a particular professor, the young man was aloccurred to interrupt this illusion, he should have lowed by his protector to have a small supper stopped instantly." And Sir James Mackin- party, at which he was very merry. Next day, tosh, who could repeat whole pages of a book on after giving in the essay, he took a game at ball the Brownonian system which he had read thirty with some companions, in the course of which he years before, always acknowledged that he was fell on his rump and experienced a slight conguided by a recollection of the actual appear-cussion of the brain. Coming home, he was ance of the pages of the book itself. The signs found to talk incoherently, and he had no recolof thought, we may suppose, are more easily re-lection of either the supper party or the delivery membered than the direct thought itself, because of the prize essay. He was immediately put to † Idem. bed and bled, when he gradually, as with an ef

* Abercromby.

of silver, may be, in comparison with a piece of Herchel's paper which bore an image yesterday, and none to-day, exactly what an old man's memory of remote events is to his recollection of recent occurrences.

fort, came to a faint recollection of these inci- new course of instruction. Suddenly, he recovdents, but remembered nothing which took place ers all that was lost, but has forgot every new after the fall; and the few hours which elapsed idea acquired since his recovery. In some cases, between that event and the bleeding continued the two conditions have alternated oftener than ever after to be a complete blank in his memory. once. Dr. Beattie mentions a clergyman who, There are remarkable instances of a revival on recovering from an apoplectic attack, was of old and forgotten impressions in a state of dis- found to have lost the recollection of exactly four ease, particularly with regard to languages. years; cvery thing that occurred before that pe"A man, mentioned by Mr. Abernethy, had been riod he remembered perfectly. He gradually born in France, but had spent the greater part of recovered the lost knowledge, partly by a sponhis life in England, and for many years had en-taneous revival of his memory, and partly by tirely lost the habit of speaking French. But reading histories of the period. How like is all when under the care of Mr. Abernethy, on ac- this to what has been stated about Möser's vancount of the effects of an injury of the head, he ishing but revivable pictures! always spoke French. A similar case occurred Many of the recorded phenomena of dreaming in St. Thomas's Hospital, of a man who was in also seem to bear a strong relation to the Moser a state of stupor in consequence of an injury of process. The metaphysicians make out a class the head. On his partial recovery, he spoke a of dreams as consisting of the revival of ideas language which nobody in the hospital under- which had passed out of the mind, or appeared stood, but which was soon ascertained to be to have been forgotten. For example, a gentleWelsh. It was then discovered that he had been man, about to be cast in a law-suit for want of a thirty years absent from Wales, and, before the particular document which has been lost, dreams accident, had entirely forgotten his native lan- a dream in which his deceased father or some guage. On his perfect recovery, he completely other person appears, and informs him of the forgot his Welsh again, and recovered the Eng-place in which it is deposited. The theory relish language. ** A case has been related to specting such cases is that the fact was once me of a boy, who, at the age of four, received a known, but became forgotten, and the informafracture of the skull, for which he underwent the tion given in the dream was only a resurrection operation of trepan. He was at the time in a of this deceased piece of knowledge. And that state of perfect stupor, and, after his recovery, we are capable of thus utterly forgetting a piece retained no recollection either of the accident or of knowledge which we once possessed, is provthe operation. At the age of fifteen, during the ed by our frequently being reminded ef sayings delirium of a fever, he gave his mother an ac- of our own by other parties to whom we had count of the operation, and the persons who spoken them, but of which we have no recollecwere present at it, with a correct description of tion. The revival of these lost ideas may be their dress, and other minute particulars. He only a physical process in the brain, of the same had never been observed to allude to it before, nature with the vaporing of an occult photoand no means were known by which he could graphic picture. Dr. Watts by anticipation gives have acquired the circumstances which he men- a sort of countenance to such a supposition, when tioned. An eminent medical friend informs me, he conjectures "that those very fibres, pores, or that, during fever, without any delirium, he on traces of the brain, which assist at the first idea or one occasion repeated long passages from Ho- perception of any object, are the same which assist mer, which he could not do when in health; and also at the recollection of it." Even the language another friend has mentioned to me, that, in a of the metaphysicians, vague as it generally is, similar situation, there were represented on his seems strangely in harmony with that of our mind, in a most vivid manner, the circumstances new science. They describe conception and imof a journey in the Highlands, which he had per-agination as two different degrees of activity of formed long before, including many minute par- the intellectual powers in reviving past impres ticulars which he had entirely forgotten. ** sions. Dr. Brown, the last and best of this seAn ignorant servant girl, mentioned by Cole-ries of philosophers, taught that "there is a law ridge, during the delirium of a fever, repeated of the mind over which volition has no control, passages from theological works in Latin, Greek, or a tendency, which is constantly operating inand Rabbinical Hebrew, which, being taken voluntarily, to renovate prior feelings. This he down and traced to the works from which they called Simple Suggestion. When two or more were derived, were found to be repeated with objects, or two or more thoughts, primary or reperfect accuracy. It turned out that she had novated, are present to the mind, feelings of rebeen servant to a clergyman, a man of much lation arise in it independently of the will, and learning and peculiar habits, who was in the from a law or tendency of the mind itself. This practice of walking backwards and forwards he called Relative Suggestion. Lastly, there is along a passage in his house which led to the in the mind a susceptibility of, or tendency to, kitchen, and there reading aloud his favorite au- another distinct class of feelings, called Emothors."* Of this class of phenomena many oth- tions, as Grief, Joy, Pleasure, Pain, Cheerfuler examples might be adduced. There is an-ness, Wonder, Fear, Remorse, &c. These feelother class, which have obtained the general name of double consciousness. A person becomes ill, and at his recovery is found to have forgot all previously attained knowledge. He begins, like a child, with the alphabet, and goes through a

Abercromby.

ings are also involuntary. They arise unbidden in the mind, when certain objects are seen, or certain feelings of relation perceived." This is an abstract of the principal parts of Dr. Brown's doctrine, which was given out thirty years ago.

We find it in the Edinburgh Magazine, 1820.