Towler, John. The Silver Sunbeam. Joseph H. Ladd, New York: 1864. Electronic edition prepared from facsimile edition of Morgan and Morgan, Inc., Hastings-on-Hudson, New York. Second printing, Feb. 1974. ISBN 871000-005-9

Chapter I.
HISTORY OF PHOTOGRAPHY.

EVERY step, whether thoughtlessly or discreetly taken, is the commencement of a new era in a man's life. As in a game of chance-where either red or black must occur at the cessation of motion in the finger of the dial-plate-the probability that red will prevail over the black the next time, because black has occurred for twenty times in succession, is not valid; it is equally probable that black will be the successful color; so, in the game of life, each successive move is a new beginning; and, as a single twirl of the roulette may be the bane or the boon of the career of an individual, so the slightest event, the most insignificant indeed, may turn out to be the center of incalculable results. New developments in the science of nature are not limited to their own immediate sphere; they act and react upon the past and the future, by illustrating phenomena that before were dark and not understood, or by eliciting truths which hitherto were utterly unknown. Thus it is that the invention of a machine, the improvement of a part of a machine, or the discovery of some new chemical ingredient, may be the date of the commencement of a new history. The verification of this idea is pertinently made manifest in the change from the simple double convex lens to the achromatic combination by Dolland;¹ in the change from the signal telegraph on the mountains to the electric telegraph in the closet; in the improved application of steam by Watt; in the development of a picture on the iodized plates of silver by the vapor of mercury; and in the discovery of the hyposulphite of soda, cyanide of potassium, pyrogallic acid, and the protosalts of iron. For from the moment that chromatic and spherical aberration could be reduced, the telescope and the microscope became altogether new instruments in the hands of the natural philosopher, by which many crude notions were quickly laid aside as false, and many new truths as quickly denuded of their cloudy habiliments. Astronomy, one of the oldest of sciences-one whose history can be traced back to the time of the Chaldeans entered, at the time of the introduction of the achromatic refracting telescope, upon an epoch as distinct in its history as the transition from the system of Hipparchus to that of Copernicus. At the same time, too, Physiology received a new impetus, by the deductions drawn with the aid of the compound achromatic microscope, so that Biology, since then, is gradually becoming more and more of a science. By means of the former improved instrument, our eyes are permitted to revel amid the enchanting scenes of the starry firmament, by the latter to scrutinize the realms of minute organisms of the earth, and by both to become acquainted with the secrets of creation. For the investigator of nature in the great and the minute, this is a new era in the history of the world as it exists and acts. In like manner the age of steam and the telegraph commenced a new history in the social existence and actions of men. The mild tenets of the Gospel, which would seem to have no connection whatever with the subject, have been more powerfully, more efficaciously implanted in foreign soils, by the accessory instrumentality of these agents, than by any preceding direct operations of the missionary organization; the superiority of the race of men that have invented and that ´yield such mighty instruments for weal and for woe, is so distinctly marked, that admiration and awe have engendered, in the minds of the ignorant and less enlightened, respect for the creeds of religion and morality of their superiors. Coexistent with the steam-engine and the electric telegraph, and equally important as these in its influence on the ways and means of life, is the art of sun-drawing. It is one of the great wonders of the phenomena of created matter, so far eclipsing the seven vaunted wonders of the world, that these recede into dark nooks, like the wired dolls of an automata puppet-show. This art, and the science that explains the different effects produced in its manipulations, form the subject of the present volume. The art and the science are of modern origin and of recent date.

Sun-drawing, Heliography, and Photography are synonymous expressions for the same phenomenon, although etymologically the two latter are somewhat different-heliography signifying sun-writing, whilst the word photography signifies light-writing. Not one of these expressions is strictly correct, because actinic impressions can be obtained from rays emanating from the moon, from artificial light, or the electric spark. Actinic drawing would probably be the best name, although as regards the representation of facts by words, it is immaterial for the masses of mankind whether these words have an intrinsic or root-meaning or not. The phenomena comprehended under any one of the above synonymous expressions, depend immediately upon what is termed light as the force or cause, and upon the property, which only certain substances apparently possess, of being affected according to the intensity of the light employed. The principal of these substances are the salts of silver, the salts of iron, bichromate of potassa, and certain resins, as the oil of lavender and asphaltum. That light acts upon organized substances is a phenomenon which must have been observed by the first occupants of earth; they could not fail to remark the brilliant hues on the side of an apple that received the direct rays of the sun, and to contrast these resplendent mixtures of red, crimson, green, purple, yellow, orange, and other colors, on the one side, with the white, or greenish white, on the side exposed simply to the diffused light of day. The variegated foliage of a tropical clime, as contrasted with the continual merging into green, according to the increase in latitude, gives evidence of the influence of actinic action; and this change of green into white in the leaves and stalks of similar plants, when supplied with heat and air, and not with light, is a still stronger proof of heliographic influence. But this species of influence is not limited to the vegetable part of the earth; it is perceived, in all its beauties, in the blooming cheeks of a maiden from Kaiserstuhl in the Black Forest, or from the pasturing declivities of the Tyrolese Alps; and its deficiency is quite as apparent in the pale, white, and lifeless facial integuments of the unfortunate denizens of crowded cities, as in the blanched stalks of celery in a dunghill, or the sickly white filiform shoots of potatoes in a dark cellar. These phenomena are full of wonder, no less so than any of the operations of sun-drawing on paper or collodion, and quite as inexplicable; but they have long failed to excite astonishment, from the frequency and commonness of their occurrence.

The first remark in reference to the cause of the change of color in silver salts is due to the distinguished Swedish chemist, Scheele.² He regarded the blackening effect of chloride of silver, when exposed to the rays of the sun, as caused by a species of reduction of the salt to the metallic state and the accompanying formation of hydrochloric acid. He undertook a course of experiments, to ascertain whether all the colors of the spectrum had an equal influence in coloring or blackening this salt, and arrived at the conclusion that the maximum chemical or decomposing action of the spectrum was in the neighborhood of the violet part, and that it gradually diminished toward the red, where it was scarcely perceptible. The researches of Scheele in this track terminated here; and no application of the property of blackening of the chloride of silver to photogenic purposes was made until after the lapse of several years.

In 1801 Rittert³ not only corroborated the experiments of Scheele, but demonstrated that chloride of silver was blackened to some distance external to the spectrum, on the violet side. The scientific investigators of the time repeated the experiments without any further developments.

Dr. Wollaston⁴ published a report of experiments which he made with gum-guaicum, when acted upon by the different colored rays of the spectrum. The violet rays t[illegible]d I paper, stained yellow by a solution of this gum in a[illegible]ol, to green, which was soon changed back to yellow by the red rays; he discovered afterward, however, that the heat of the red rays was sufficient of itself to reproduce the yellow color of the tincture of the gum.

The same results were obtained by Bérard. He experimented with half the spectrum at a time, which was condensed by a lens to a focus, and made to impinge at this point upon chloride of silver. The half next the violet, or more refrangible rays, were very efficacious in discoloring this salt of silver; whilst the other half, or red side, and least refrangible rays, although far more luminous, produced no blackening effect. The experiments of Seebeck seem to show that light transmitted through colored glass produced the same general effect as the different colored rays of the spectrum. He furthermore ascertained that a piece of paper dipped in a rather concentrated and neutral solution of chloride of gold, in the dark, was not reduced, as long as it was kept in the dark; whereas if it had previously been exposed to the direct rays of the sun, it gradually turned purple in the dark chamber. Sir Humphry Davy observed that the oxide of lead, in a moist condition, is acted upon very differently by the red and the violet rays of the spectrum; by the latter, the puce-colored oxide is turned black-by the former, red. He ascertained, too, that hydrogen and chlorine, when exposed to the rays of the sun, frequently enter into combination so vividly as to produce an explosion in the formation of hydrochloric acid; but the two gases may be kept in contact, in the dark, without undergoing much change. A solution of chlorine in water remains unchanged, as long as it is kept out of the light; but is soon converted into hydrochloric acid, by decomposing the water, when exposed to the sun. A similar case of decomposition is effected by light, when carbonic oxide and chlorine are exposed to light; they then enter into combination chemically, condensing into a substance denominated phosgene gas.

The preceding remarks comprehend the sum and substance of the knowledge of the chemical effects of light previous to its application to the taking of impressions of pictures by the salts of silver or otherwise. It is true that a certain Hoffmeister published some vague remarks about the sun being an engraver, several years previous to Daguerre's publication; but they were the mere remarks of one who probably thought the thing possible without possessing the most distant idea of the mode of its effectuation. And in the report which Arago made to the Chamber of Deputies in reference to Daguerre's discovery, this distinguished philosopher mentions the name of Charles as having been in possession of a process for communicating pictures, by the aid of the sun, to prepared surfaces. No publication has been discovered to corroborate this assertion, and the details of the operation have never been disclosed.

The first recorded attempts by Wedgwood⁵ and Davy,⁶ to take pictures by the rays of the sun on a prepared silver surface, were published in the year 1802. The receptacle of the picture was either paper or leather, or some other convenient material, stretched upon a frame, and sponged over with a solution of nitrate of silver; over this prepared surface a painting on glass was placed in direct contact and exposed to the rays of the sun. It is evident that the picture thus obtained would be inverted as to light and shade. The difficulty, which at this time could not be overcome, was the fixing of the picture; and the process was abandoned on this account. No chemical substance was known whose peculiar properties were of such a nature as to dissolve the unaltered salt of silver and leave the portions on which the image was projected untouched or uninjured. These experiments of Wedgwood were actually made several years previous to the publication in 1802; because at that date lie had been dead for seven years. The surface prepared with nitrate of silver was not sensitive enough to receive an impression in the camera obscura, although Sir Humphry Davy succeeded in getting a very faint image in the solar microscope, where the picture was very much condensed in size or situated very near the focus of parallel rays. From that date to the year 1814 not only no other publication appeared, but there are no accounts of any one having prosecuted the study of sun-drawing. At this time a new laborer entered the field of investigation and directed all his mental energies to the discovery of means of making sun-pictures. From the work of Daguerre, which was published several years later, it appears that Niepce⁷ was the fast who obtained a permanent sun-picture; to him we are indebted for the, first idea of a fixing material; it was he who first employed silver and the vapor of iodine. The process of Niepce had been so far perfected as to admit the use of the camera, which, by reason of the want of sensitiveness in the materials used; had remained a useless optical arrangement. Niepce, in his experiments, discarded the use of the silver salts, and substituted in their place a resinous substance denominated the 11 Bitumen of Judea." He named his process "Heliography," or " Sun-drawing." His pictures were produced by coating a metal plate with the resinous substance above alluded to, and then exposing this plate, under a picture on glass, or in the camera, for several hours in front of the object to be copied. By this exposure to light the parts of the bitumen which had been acted upon by the rays underwent a change according to the actinic intensity, whereby they became insoluble in certain essential oils. By treatment afterward with these essences, as, for instance, the oil of lavender, the picture was developed, the shadows being formed by the brilliant surface of the metal exposed, by the solvent action of the essential oil in those parts of the resin on which the rays of light had not impinged; whilst the lights were represented by the thin film of bitumen which had become altered and insoluble in the oleaginous substance employed in fixing. Some of the specimens produced by this method at this period exist still in the British Museum; some of them are in the form of etchings, having been acted upon probably by the galvanic current. It is evident that Niepce was acquainted with a method of fixing his sun-drawings; but his successes were limited to productions which now would be regarded very trivial and unsatisfactory. After ten years' labor in the prosecution of his favorite investigation, by some accidental disclosure, Niepce became acquainted with Daguerre,⁸ who had been experimenting independently in the same path. Daguerre's experiments with chemical processes and the camera date from the year 1824; and in 1829 these two great originators of sun-drawings entered into partnership for mutually investigating this enchanting art. In 1827 Niepce had presented an article to the Loyal Society of London on this subject; but as yet Daguerre had not arrived at any successful results, nor had be published any thing in reference to them. The process of Daguerre aimed to perform the same operation by the same method, that is, by light; the materials for the sensitive surface, for developing and fixing alone, being different. Iii this process are found the use of the camera, iodide of silver on a metal plate, mercury as a developer, and hyposulphite of soda as a fixing agent; in that of Niepce, bitumen on a metal plate, iodine as a developer, and oil of lavender in place of the hyposulphite of soda. The use of the latter substance was probably suggested to Daguerre by the publication of a paper, by Sir John Herschel, on the solubility in this menstruum of the insoluble salts of silver. The image formed on the iodized surface was quite latent until brought out by the vapor of mercury. It seems wonderful how Daguerre should hit upon the idea of using this vapor, or that a latent image was on the surface. Knowing the latter and the possibility of such a development, the chemist has only to persevere in a systematic exploration among the infinite number of chemical substances, in order finally to meet with success; but Daguerre could not à priori be furnished with such positive knowledge; hence our admiration at his success, at the hardihood and perseverance of his character in search of this success, can not be otherwise than boundless. Niepce, too, is entitled to an equal share of honor; for without Niepce, in all probability, sun-drawing would still be a latent property of nature; as also, without Daguerre, the discoveries of Niepce would not stand out in that bold relief in which they are now exhibited.

The plates which Daguerre used for the reception of the heliographic image were of silver, or of copper plated with silver. The silver surface, highly polished, was subjected to the vapor of iodine in the dark-chamber; the iodide of silver thus formed being very sensitive to the actinic influence, the plate was ready for the reception of the latent image. This mode of sensitizing the surface had reduced the time of exposure from hours to minutes; and an increase of sensitiveness was attained at the suggestion of Fizeau, who recommended the use of bromine-water; and about the same time the chloride of iodine was recommended as an accelerator by Claudet; and the bromide of iodine by Gaudin. By means of these accelerators the time was again reduced from minutes to seconds. In this state of perfection we will now leave the art of heliography, or of the Daguerreotype as it is more frequently denominated, and observe only, in conclusion, that this discovery of Daguerre was reported to the world in January, 1839; but the process was not communicated until after a bill had been passed by the French government, which secured to Daguerre a pension of six thousand francs a year, and to Isidore Niepce, the son of Daguerre's partner, an annual pension for life of four thousand francs, one half of which was to revert to their widows.

That Mr. Fox Talbot was acquainted with the experiments of Niepce and Daguerre is very doubtful, because the result of these experiments was kept secret until the pensions had been granted; but Mr. Talbot states, in the communication which he made to the Royal Society on the thirty-first of January, 1839, six months before the publication of Daguerre's process, that he had been applying the property of discoloration of the silver salts by light. to useful purposes. This application consisted in preparing a sensitive paper for the copying of drawings or paintings, by direct contact. The paper was dipped, in the first place, in a solution of chloride of sodium, and afterward in one of nitrate of silver, whereby a film of chloride of silver was formed--a substance much more sensitive to light than the nitrate of silver, which had heretofore been employed for photographic purposes. The object to be copied, which had to be transparent, or partly so, was applied in direct contact with the sensitive paper, and exposed to the ray's of the sun. By this means, a copy of the object was obtained, in which the lights and shades were inverted. This was the negative, which, when fixed, was superimposed on another piece of the sensitive paper, and exposed in its turn to the rays of light, whereby a positive print was obtained of the object, in which the lights and shades were exhibited in their natural position.

The communication of Talbot is the first, which laid the foundation of multiplying copies of a picture by the combined action of light and chemical material; it gave the first idea of photographic printing.

In the year 1841 another method was devised and patented, called Talbotype or Calotype. The process consisted in preparing paper with the iodide of silver, which, when exposed to light, became the recipient of a latent image, which afterward was made to appear by the application of a developer, and was fixed with hyposulphite of soda. This method is the essential point in the present collodion process; it is, in fact, the very foundation of photography. Talbot, therefore, merits an equal position in history with Niepce and Daguerre. These three-this much to be honored trio-are the undisputed originators of that branch of natural science which hereafter will occupy a prominent part of human intelligence.

The paper, in the Calotype process, was immersed in a solution of iodide of potassium, or floated on its surface; as soon as dry, it was floated on a solution of nitrate of silver for a certain time. By this operation, a film of iodide of silver was formed by the double decomposition of the two salts in contact. The excess of iodide of potassium, or of nitrate of silver and the nitrate of potassa were afterward removed by washing in several waters. These operations had to be performed in the dark chamber, by the aid of a small candle or lamp. When the paper was required to be used, it was brushed over with a solution of one part of nitrate of silver, containing fifty grains to the ounce, two parts of glacial acetic acid, and three of a saturated solution of gallic acid; or the paper was floated on the surface of this gallo-nitrate of silver, as it is called, for a few seconds, and the excess of fluid removed by blotting-paper. By this mode of treatment, the paper was rendered very sensitive, sufficiently so to receive an impression of a living person, by means of the camera obscura. An exposure of one second, or of a fraction of a second, was found effective in producing: an impression on the Calotype paper. This impression might be totally invisible, partly visible, or distinctly visible, according to the circumstances of time, intensity of the light, and sensitiveness of the prepared paper. The latent image, or partially visible image, was then developed to any degree of depth of shades, by washing the surface of the paper with one part of a solution of nitrate of silver, of the same strength as before, and four parts of the saturated solution of gallic acid. The image gradually becomes developed by this treatment, and in a few minutes reaches its maximum degree of intensity. The fixing solutions were bromide of potassium and hyposulphite of soda. The first impression, thus obtained, was in this process, as well as in that with chloride of silver, a negative, which, by continuing the process and using this negative as an original object, either in the camera or by direct application, produced a positive, with the lights and shades in their appropriate positions.

The difficulty in this process is the want of homogeneity, and of a sufficient transparency, in the structure of paper. The want of transparency probably was regarded the greatest drawback in the production of negatives; whilst the irregularities in the fiber of the paper could never yield a surface to compete with the brilliant and even surface of a polished piece of silver for the reception of positive pictures. To obviate these disadvantages, Sir John Herschel proposed the use of glass plates, and was the first to employ them.

In the year 1847 Niepce de St. Victor, the nephew of Daguerre's partner, to whom we are indebted for many interesting publications on the Chromotype, managed to fix a film of albumen on the glass plates. This film is intimately mixed with the iodides or bromides, and flowed upon the surface of the glass. Such albumen plates are employed by many very distinguished artists at the present day, who exhibit specimens of fine and sharp definition and softness of tone in their stereographs, that have not been surpassed by any other process; as, for instance, regard those beautiful productions of Ferrier.

The next important improvement in photography was effected in 1851; it is the foundation-stone of a new era. Legray originally suggested that collodion might be used as the receptacle of the sensitive material, in place of albumen; but we are indebted to Archer for the practical application of the solution of gun-cotton, and of the mode of employment, pretty much as it now stands. Archer substituted pyrogallic acid for the gallic acid that had been previously used in the development of the latent image. Pyrogallic acid, although still used as a developer, has been since pushed aside, in a great measure, by another substitute, the sulphate of the protoxide of iron, at the Suggestion of Talbot. It is now limited principally to the operation of intensifying.

Collodion is a solution of a substance very much resembling gun-cotton in ether and alcohol. A decided improvement, in many respects, has been made in this solution, at the suggestion of Sutton, the editor of the Photographic Notes, who recommends an excess of alcohol. When this solution is poured upon a piece of clean glass, it forms a very thin, even, and transparent film, which quickly dries, and can scarcely be distinguished from the surface of the glass beneath it. It contains the materials for sensitization. The discovery and application of this substance have given rise to what is denominated the collodion process. It is impossible to calculate the impetus given to photography by this discovery, or its value to society, in the promotion of comfort and happiness; much less can an idea be conceived of the resources to which it may give rise by its future developments.

In the year 1838 or 1839, Mr. Mungo Ponton pointed out a very important discovery in reference to bichromate of potassa, when acted upon by light, whereby this salt, the chromic acid, or (as Mr. Talbot advances) the organic matter with which the salt is in combination, becomes insoluble. The paper for experimenting on this point is uniformly coated with a mixture of bichromate of potassa, gelatine, and lampblack in cold distilled water, and allowed to dry in the dark room. When dry, it is ready to be placed beneath a negative. The time varies from four or five minutes to a quarter of an hour or upward. The impression obtained in this way is quite latent, and is made to appear by dissolving off, with hot water, those parts that have been entirely or partially excluded from the actinic influence of the light. The picture resulting from this treatment is a positive print, in black and white, of which the shades are produced by the carbon of the lampblack. This discovery gave rise to carbon-printing.

In the year 1852 a patent was taken out in England by Talbot, reserving to himself the sole use of bichromate of potassa and gelatine in the production of photo-engravings on steel. Three years after this date, that is, in 1855, Poitévin patented a process for making carbon prints by means of the same materials combined with coloring matter, as well as for obtaining a photographic image on a lithographic stone, capable of being printed from by the ordinary lithographic press. In Talbot's process the steel plates were covered with a coating of bichromate of potash and gelatine, the operation taking place in the dark chamber. A transparent positive is then placed on its surface, and the plate is then exposed to the light. The latent image is developed as before alluded to. Afterward the edges of the plate are raised with wax, or some resinous preparation, so as to form a sort of dish, into which is poured the acid or etching-fluid, which etches away the parts exposed by the removal of the soluble gelatine. The etching-fluid used by Talbot was the bichloride of platinum. Poitévin's process is in principle the same. The disadvantage in the latter process arises from the want of durability in the image, which, being formed out of organic matter lying, as it must do, between the ink and the stone, is liable to be soon abraded after a few pictures have been printed from it. These attempts have created a number of improvements, by which matrixes can now be furnished, by the aid of photography, for the engraver's press, the lithographic press, and the typographic press.

Messrs. Cutting and Bradford took a patent out, in this country, for a process in which the image is formed directly of greasy ink used in lithography.

The next important step in photo-lithography is that in which the picture is first formed by bichromate of potash and gelatine on lithographic transfer-paper, that is, paper coated with a layer of albumen. A negative is placed in direct contact with paper so prepared, from which an image is obtained, that is, after certain other operations, transferred directly, in lithographic ink, to the stone. This process was patented in 1859, at Melbourne, in Australia, by Mr. Osborne, for which he was awarded by the government of the colony of Victoria the sum of one thousand pounds. This process promises to be the basis of the most successful operations in photo-lithography.

Asser, of Amsterdam, invented or used the transfer process at the same time that Osborne was using it in Australia.

Colonel Sir Henry James makes use of zinc, upon which he transfers the image formed in ink; the image having been produced on engraver's tracing-paper by the means adopted by Talbot, Poitévin, and Osborne.

In the year 1859 another process for photo-lithographic purposes was patented in Vienna, in Austria, in which asphaltum is again brought into the field. The developer is oil of turpentine and water. The latent image is produced in a film consisting of a solution of asphaltum in chloroform, by means of a collodion negative exposed for a number of hours. As soon as the soluble asphaltum has been removed, the remaining insoluble parts which form the shades of the image are coated with a layer of ink by the printer; the image is then gummed in, and slightly etched; after which it is ready for the press.

Poitévin has just published a new method of direct carbon-printing on paper. It depends upon the insolubility communicated to certain organic matters, such as gum, albumen, gelatine, etc., by the per-salts of iron, and on a new fact observed by him, namely, that this matter, coagulated and rendered insoluble in cold and even in hot water, becomes soluble under the influence of light, and in contact with tartaric acid, which, by the reduction of the iron salt, restores to the organic matter its natural solubility. The paper for carbon-printing is floated in a bath of gelatine dissolved in water and colored with a sufficient quantity of lampblack, or other coloring matter, and maintained at a lukewarm temperature. The paper becomes thus uniformly covered with the colored gelatine.

The sensitizing part is performed in the dark room by plunging each sheet into a solution of sesquichloride of iron and tartaric acid in water. By this immersion the gelatine becomes quite insoluble even in boiling water. The sheets are taken out and dried. The prints are obtained by placing transparent positives in direct contact with the paper in the printing-frame Two or three minutes' exposure to the rays of the sun will be found sufficient to render those parts through which the light has passed soluble in boiling water, which is the developer and fixing agent at the same time. A little acid water is used toward the end of the washing, in order to remove all traces of the ferruginous compound.

Poitévin has other methods of producing direct carbon-prints, which, together with this and others preceding, will be fully discussed in their proper place.

Niepce de St. Victor has long been experimenting in his favorite study of the chromotype. He has succeeded in producing photogenic impressions endowed with certain colors of the original. Yellow is found very difficult to transfer to the heliochromic plate at the same time with other colors. Red, green, and blue, it appears, could be formerly reproduced satisfactorily. In the fifth memoir of Niepce on this subject, the author states that he can now reproduce yellow along with other colors in a definite manner. The trouble with these heliochromic specimens is still their want of permanence. At the very most, the colors can not be preserved longer than two or three days. The problem to be settled is the means and mode of fixation.

Notes

¹ Dolland, J., was born in London, in the year 1706, and died in 1762.

² Scheele, Charles William, was born on the nineteenth of December, 1742, at Stralsund, Sweden. He died on the twenty-first of May, 1786, at Koeping, on Lake Moeler.

³ Bitter, John William, was born at Samitz, in Silesia, in 1 776, and died in 1810.

⁴ Wollaston William Hyde M.D., was born on the sixth of August, 1766, at East-Dereham, and died December twenty-second, 18´).8, in London.

⁵ Wedgwood, Josiah, was born at Newcastle-under-Lyne, in 1730, and died in the year 1795.

⁶ Sir Humphry Davy was born at Penzance, in 1778, and died at Geneva, in 1828.

⁷ Niepce, Joseph-Nicéphore, was born at Chalon-sur-Saône, and died in 1833.

⁸ Daguerre, L.J.M., was born at Cormeilles, in 1787, and died in 1851.