Early Telescopes—The Lick Telescope—The Grande Lunette—The Stereo-Binocular Field Glass—The Microscope—The Spectroscope—Polarization of Light—Kaleidoscope—Stereoscope—Range Finder—Kinetoscope and Moving Pictures.
“And God said, Let there be light: and there was light. And God saw the light that it was good; and God divided the light from the darkness.” Thus early in the account of the creation is evidenced man’s appreciation of the value of vision. Of all the senses which place man in intelligent relation to his environment none is so important as sight. More than all the others does it establish our relation to the material world. When the babe is born, and its little emancipated soul is brought in contact with the world, its wondering gaze sees the panorama of visible things touching its eyes, and it stretches forth its tiny arms in the vain effort to pluck the stars, apparently within its reach. Distance and time add their values to light and vision, and as his life expands to greater fullness, the perspective of his existence creeps into his consciousness, and he finds himself farther away, but still peering beyond into the infinity of distance, searching for the visible evidence of knowledge. From the earliest times man learned to spurn the groveling things of earth, and to delight his soul with the marvelous infinity of the sky and its heavenly bodies. Nunc ad astra was his ambitious cry, and in no field has his quest for knowledge been more skillfully directed, faithfully maintained, or richly rewarded than in the study of astronomy. Many important discoveries in this field have been made in the Nineteenth Century, among which may be named the discovery of the planet Neptune by Adams, Leverrier and Galle in 1846; the satellites of Neptune in 1846, and those of Saturn in 1848 by Mr. Lassell; the two satellites of Mars by Prof. Asaph Hall in 1877; and the discovery of the so-called canals of Mars by Schiaparelli in 1877. But the purpose of this work is to deal with material inventions rather than scientific discoveries, and the leading invention in optics is the telescope.
Who invented the telescope is a question that cannot now be answered. For many years Galileo was credited in popular estimation with having made this invention in 1609. But it is now known that, while he built telescopes, and discovered the mountains of the moon, the spots on the sun’s disk, the crescent phases of Venus, the four satellites of Jupiter, the rings of Saturn, and made the first important astronomical observations, the invention of the telescope, as an instrument, could not be rightly claimed for him. Borelli credits it to Jansen & Lippersheim, spectacle makers, of Middelburg, Holland, about 1590; Descartes credits it to James Metius; Humboldt says Hans Lippershey (or Laprey), a native of Wesel and a spectacle maker of Middelburg in 1608, naming also Jacob Adriansz, sometimes called Metius and also Zacharias Jansen.
The great impetus given to the study of astronomy by Galileo, in 1609, was followed up by Huygens in 1655 with his improvement, by Gregory’s reflecting telescope of 1663, and Newton’s in 1668. In 1733 Chester More Hall invented the achromatic object glass of crown and flint glass. In 1758 John Dolland reinvented and introduced the same in the manufacture of telescopes. In 1779 Herschel built his reflecting telescope, and in March, 1781, he discovered the planet Uranus. In 1789 he built his great reflector. It was while the latter telescope was exploring the heavens that the Nineteenth Century began, and in the early part of this century Herschel laid before the Royal Society a catalogue of many thousand nebulæ and clusters of stars. Among the great telescopes of the Nineteenth Century may be mentioned that made in London in 1802 for the observatory of Madrid, which cost £11,000; the great reflecting telescope of the Earl of Rosse, erected at Parsonstown, in Ireland, in 1842-45. This was 6 feet diameter, 54 feet focal length, and cost over £20,000; the magnificent equatorial telescopes set up at the National Observatories at Greenwich and Paris in 1860; Foucault’s reflecting telescope at Paris, 1862, whose mirror was 311⁄2 inches diameter, and focal length 173⁄4 feet; Mr. R. S. Newall’s telescope, set up at Gateshead by Cookes, of York, in 1870; object glass, 25 inches, tube, 30 feet; Mr. A. Ainslie Common’s reflecting telescope, Ealing, Middlesex, 1879, mirror, 371⁄2 inches diameter, tube, 20 feet; the telescope at the United States Observatory, at Washington, 1873, object glass, 26 inches, tube, 33 feet long; and the large refracting telescope by Howard Grubb, at Dublin, for Vienna, 1881.
In more recent times the great refracting telescope by Alvan Clark & Sons, for the Lick Observatory on Mount Hamilton, California, in 1888, attracted attention as superior to anything in existence up to that time. This is shown in Fig. 194. The supporting column and base are of iron, weighing twenty-five tons. This rests on a masonry foundation, which forms the tomb of James Lick, its founder. The tube is 52 feet long, 4 feet diameter in the middle, tapering to a little over 3 feet at the ends. The object glass is 36 inches in diameter, and weighs, with its cell, 530 lbs. The steel dome is 75 feet 4 inches in diameter, and the weight of its moving parts is 100 tons. This instrument was perfectly equipped with all gauges, scales, photographic and spectroscope accessories, and fulfilled the condition imposed in the trust deed of James Lick, of being “superior to and more powerful than any telescope made.” It is a giant among instruments of precision, and its ponderous aspect still asserts the dignity of its purpose, and impresses even the frivolous visitor with a silent and thoughtful respect.
It is not to be understood, however, that the great Lick telescope still maintains its supremacy. The Yerkes telescope, which was exhibited at the World’s Fair Exposition in 1893, at Chicago, had an object glass of 3.28 feet in diameter and a focal distance of 65 feet, and it moved around a central axis in a vast cupola or dome 78 feet in diameter. The Grand Equatorial of Gruenewald, at the recent Berlin Exposition, was even still larger, since its object glass was 3 feet 7 inches, or nearly 2 inches larger than the Yerkes.
Even these great instruments have now been excelled in the Grande Lunette, of the Paris Exposition, in 1900. When it is remembered that an increase in the diameter of any circular body causes, for every additional inch, a vastly disproportionate increase in the cross-sectional area and weight, it will readily be seen how handicapped the instrument maker is in any increase in the power of such a telescope. An increased diameter of a few inches in the glass lens means an enormous increase in the cross section, its weight and the difficulties attending its successful casting free from imperfections, and the perfect grinding and polishing of the lens. An increased length of the tubular case of the telescope is liable to involve, from the great weight, a slight bending or springing out of axial alignment when supported near the middle for equatorial adjustment, and a few feet increase in the diameter of the massive and movable steel dome add greatly to the weight and incidental difficulties of constructing and delicately adjusting it. The great Lunette, see Fig. 195, changes entirely the method of manipulating the telescope, and also, in a measure, its principle of action, so as to avoid some of these difficulties. Its tube, instead of being pointed upwardly through the slot of a movable dome, and made adjustable with the dome, is laid down horizontally on a stationary base of supporting pillars, and an adjustable reflecting mirror and regulating mechanism, called a “siderostat,” is arranged at one end, to catch the view of the star, or moon, and reflect it into the great tube, and through its lenses on to the screen at the other end. The tube is 197 feet long, and the object glass or lens is a fraction over 4 feet in diameter. There are two of these, which together cost $120,000. The siderostat is supported on a large cast iron frame, and is provided with clockwork and devices for causing the mirror to follow the movement of the celestial object which is being viewed. The entire weight of the siderostat and base is 99,000 pounds, the movable part weighs 33,000 pounds, and the mirror and its cell weigh 14,740. The mirror itself is of glass, weighs 7,920 pounds, is 6.56 feet in diameter, and 10.63 inches thick. To facilitate the free and sensitive adjustment of this great mirror its base floats in a reservoir of mercury. The entire cost of the instrument is said to be over 2,000,000 francs. With the wonderful strides of improvement in all fields of invention, it is not unreasonable to suppose that the revelations in astronomy may keep pace with those of mundane interest, and that great discoveries may be made in the near future. The average individual does not bother himself much about the calculation of eclipses, or the laws which govern the movements of an erratic comet. He is, however, intensely personal and neighborly, and what he wants to know is, Is Mars inhabited? and if so, are its denizens men, and may we communicate with them? The wonderful regularity of the so-called canals, of apparently intelligent design, already discovered on the surface of Mars, has stimulated this neighborly curiosity into an expectant interest, and who knows what marvelous introductions the modern telescope may bring about?
Many minor improvements have been made in recent years in the form of the telescope known as field and opera glasses. Probably the most important of these is the Stereo-Binocular, invented by Prof. Abbe, of Germany, and patented by him in that country in 1893, and also in the United States, June 22, 1897, No. 584,976. This gives a much increased field, and also an increased stereoscopic effect, or conception of relative distance, by having the object glasses wider apart than the eyes of the observer. The field is also flatter, the instrument rendered very much smaller and more compact, and no change of focus is required for changing from near-by to remote objects. The rays of light, see Fig. 196, enter the object glasses, strike a double reflecting prism, and are first thrown away from the observer, and then striking another double reflecting prism, arranged after Porro’s method, are returned to the observer in line with the eye-piece.
The Microscope.—Just as the telescope reveals the infinity of the great world above and around us, so does the microscope reveal the infinity of the little world around, about, and within us. Its origin, like the telescope, is hidden in the dim distance of the past, but it is believed to antedate the telescope. Probably the dewdrop on a leaf constituted the first microscope. The magnifying power of glass balls was known to the Chinese, Japanese, Assyrians and Egyptians, and a lens made of rock crystal was found among the ruins of Ninevah. The microscope is either single or compound. In the single the object is viewed directly. In the compound two or more lenses are so arranged that the image formed by one is magnified by the others, and viewed as if it were the object itself. The single microscope cannot be claimed by any inventor. The double or compound microscope was invented by Farncelli in 1624, and it was in that century that the first important applications were made for scientific investigation. Most of the investigations were made, however, by the single microscope, and the names of Borelli, Malpighi, Lieberkuhn, Hooke, Leeuwenhoek, Swammerden, Lyonnet, Hewson and Ellis were conspicuous as the fathers of microscopy. For more than two hundred and fifty years the microscope has lent its magnifying aid to the eye, and step by step it has been gradually improved. Joseph J. Lister’s aplanatic foci and compound objective, in 1829, was a notable improvement in the first part of the century, and this has been followed up by contributions from various inventors, until the modern compound microscope, Fig. 197, is a triumph of the optician’s art, and an instrument of wonderful accuracy and power. Its greatest work belongs to the Nineteenth Century.
Multiplying the dimensions of the smallest cells to more than a thousand times their size, it has brought into range of vision an unseen world, developed new sciences, and added immensely to the stores of human knowledge. To the biologist and botanist it has yielded its revelations in cell structure and growth; to the physician its diagnosis in urinary and blood examinations; in histology and morbid secretions it is invaluable; in geology its contribution to the knowledge of the physical history of the world is of equal importance; while in the study of bacteriology and disease germs it has so revolutionized our conception of the laws of health and sanitation, and the conditions of life and death, and is so intimately related to our well being, as to mark probably the greatest era of progress and useful extension of knowledge the world has ever known. In the useful arts, also, it figures in almost every department; the jeweler, the engraver, the miner, the agriculturalist, the chemical manufacturer, and the food inspector, all make use of its magnifying powers.
To the microscope the art of photography has lent its valuable aid, so that all the revelations of the microscope are susceptible of preservation in permanent records, as photomicrographs. A curious, but very practical, use of the microscope was made in the establishment of the pigeon-post during the siege of Paris in 1870-71. Shut in from the outside world, the resourceful Frenchmen photographed the news of the day to such microscopic dimensions that a single pigeon could carry 50,000 messages, which weighed less than a gramme. These messages were placed on delicate films, rolled up, and packed in quills. The pigeons were sent out in balloons, and flying back to Paris from the outer world, carried these messages back and forth, and the messages, when reaching their destination, were enlarged to legible dimensions and interpreted by the microscope. It is said that two and a half million messages were in this way transmitted.
The Spectroscope.—To the popular comprehension, the best definition of any scientific instrument is to tell what it does. Few things, however, so tax the credulity of the uninformed as a description of the functions and possibilities of the spectroscope. To state that it tells what kind of materials there are in the sun and stars, millions of miles away, seems like an unwarranted attack upon one’s imagination, and yet this is one of the things that the spectroscope does. A few commonplace observations will help to explain its action. Every schoolboy has seen the play of colors through a triangular prism of glass, as seen in Fig. 198, and the older generation remembers the old-fashioned candelabras, which, with their brilliant pendants of cut glass cast beautiful colored patches on the wall, and whose dancing beauties delighted the souls of many a boy and girl of fifty years ago. This spread of color is called the spectrum, and it is with the spectrum that the spectroscope has to deal. The white light of the sun is composed of the seven colors: red, orange, yellow, green, blue, indigo, and violet. When a sunbeam falls upon a triangular prism of glass the beam is bent from its course at an angle, and the different colors of its light are deflected at different angles or degrees, and consequently, instead of appearing as white light, the beam is spread out into a divergent wedge shape, that separates the colors and produces what is called the spectrum. This discovery was made by Sir Isaac Newton, in 1675.
In 1802 Dr. Wollaston, in repeating Newton’s experiments, admitted the beam of light through a very narrow slit, instead of a round hole, and noticed that the spectrum, as spread out in its colors, was not a continuous shading from one color into another, but he found black lines crossing the spectrum. These black lines were, in 1814, carefully mapped by a German optician, named Fraunhofer, and were found by him to be 576 in number. The next step toward the spectroscope was made by Simms, an optician, in 1830, who placed a lens in front of the prism so that the slit was in the focus of the lens, and the light passing through the slit first passed through the lens, and then through the prism. This lens was called the “Collimating” lens. With these preliminary steps of development, Prof. Kirchhoff began in 1859 his great work of mapping the solar spectrum, and he, in connection with Prof. Bunsen, found several thousand of the dark lines in the spectrum, and laid the foundation of spectrum-analysis, or the determination of the nature of substances from the spectra cast by them when in an incandescent state.
The form of Kirchhoff’s spectroscope is given in Fig. 199. The slit forming slide is seen on the far end of the tube A, and is shown in enlarged detached view on the right. The collimating lens is contained in the tube A. The beam of light entering the slit at the far end of the tube A, passes through the lens in that tube, and then passes successively through the four triangular prisms on the table, and is successively bent by these and thrown in the form of a spectrum into the telescopic tube B, and is seen by the eye at the remote end of said tube B. The greater the number of prisms the wider is the dispersion of the rays and the longer is the spectrum, and the more easily studied are the peculiar lines which Wollaston and Fraunhofer found crossing it. It was the presence of these black lines on the spectrum which led to the development of the spectroscope and established its significance and value. The work which the spectroscope does is simply to form an extended spectrum, but this spectrum varies with the different kinds of light admitted through the slit, the different kinds of light showing different arrangement of colored bands and dark lines, and such a definite relation between the light of various incandescing elementary bodies and their spectra has been found to exist, that the casting of a definite spectrum from the sun or stars indicates with certainty the presence in the sun or stars of the incandescing element which produces that spectrum. This application of the spectroscope is called spectrum-analysis, and by rendering any substance incandescent in the flame of a Bunsen burner, and directing the light of its incandescence through the spectroscope, its spectrum gives the basis of intelligent chemical identification. So delicate is its test that it has been calculated by Profs. Kirchhoff and Bunsen that the eighteen-millionth part of a grain of sodium may be detected.
The useful applications of the spectroscope are found principally in astronomy and the chemical laboratory, but some industrial applications have also been made of it in metallurgical operations, as, for instance, in determining the progress of the Bessemer process of making steel, and also for testing alloys. Many hitherto unknown metals have also been discovered through the agency of the spectroscope, among which may be named caesium, rubidium, thallium, and indium.
The field of optics is so large that many interesting branches can receive only a casual mention. The polarization of light, first noticed by Bartholinus in 1669, and by Huygens in 1678, in experiments in double refraction with crystals of Iceland spar, were followed in the Nineteenth Century by the discoveries of Malus, Arago, Fresnel, Brewster, and Biot. Malus, in 1808, discovered polarization by reflection from polished surfaces; Arago, in 1811, discovered colored polarization; Nicol, in 1828, invented the prism named after him. The Kaleidoscope was invented by Sir David Brewster in 1814, and British patent No. 4,136 granted him July 10, 1817, for the same. The reflecting stereoscope was invented by Wheatstone in 1838, and the lenticular form, as now generally used, was invented by Sir David Brewster in the year 1849.
Among the more recent inventions of importance in optics may be mentioned the Fiske range finder (Patent No. 418,510, December 31, 1889), for enabling a gunner to direct his cannon upon the target when its distance is unknown, or even when obscured by fog or smoke. The Beehler solarometer (Patent No. 533,340, January 29, 1895), is also an important scientific invention, which has for its object to determine the position, or the compass error, of a ship at sea when the horizon is obscured. There is also in late years a great variety of entertaining and instructive apparatus in photography, and improvements in the stereopticon and magic lantern.
The most interesting of the latter is the Kinetoscope, for producing the so-called moving pictures, in which the magic lantern and modern results in the photographic art, have wrought wonders on the screen. The old-fashioned magic lantern projections were interesting and instructive object lessons, but modern invention has endowed the pictures with all the atmosphere and naturalness of real living scenes, in which the figures move and act, and the scenes change just as they do in real life.
The foundation principle upon which these moving pictures exist is that of persistence of vision. If a succession of views of the same object in motion is made, with the moving object in each consecutive figure changed just a little, and progressively so in a constantly advancing attitude in a definite movement, and those different positions are rapidly presented in sequence to the eye in detached views, the figures appear to constantly move through the changing position. The theory of the duration of visible impressions was taught by Leonardo da Vinci in the fifteenth century, and practical advantage has been taken of the same in a variety of old-fashioned toys, known as the phenakistoscope, thaumatrope, zoetrope, stroboscope, rotascope, etc.
The phenakistoscope was invented by Dr. Roget, and improved by Plateau in 1829, and also by Faraday. A circular disk, bearing a circular series of figures is mounted on a handle to revolve. The figures following each other show consecutively a gradual progression, or change in position. The disk has radial slits around its periphery, and is held with its figured face before a looking glass. When the reflection is viewed in the looking glass through the slits, the figures rapidly passing in succession before the slits appear to have the movements of life. The thaumatrope, which originated with Sir John Herschel, consists of a thin disc, bearing on opposite sides two associated objects, such as a bird and a cage, or a horse and a man. This, when rotated about its diameter, to bring alternately the bird and cage into view, appears to bring the bird into the cage, or to put the rider on the horse’s back, as the case may be. The zoetrope, described in the Philosophical Magazine, January, 1834, employs the general principle of the phenakistoscope, except that, instead of a disc before a looking glass, an upright rotating drum or cylinder is employed, and has its figures on the inside, and is viewed, when rotating, through a succession of vertical slits in the drum.
The earliest patents found in this art are the British patent to Shaw, No. 1,260, May 22, 1860; United States patents, Sellers, No. 31,357, February 5, 1861, and Lincoln, No. 64,117, April 23, 1867. In Brown’s patent, No. 93,594, August 10, 1869, the magic lantern was applied to the moving pictures, and Muybridge’s photos of trotting horses in 1872, followed by instantaneous photography, which enabled a great number of views to be taken of moving objects in rapid succession, laid the foundation for the modern art.
SHOOTING GLASS BALLS.
FIRING DISAPPEARING GUN.
FIG. 200.
SHOOTING GLASS BALLS.
FIRING DISAPPEARING GUN.
FIG. 200.
In Fig. 200 is shown a succession of instantaneous photographs of a sportsman shooting a glass ball, and the firing of a disappearing gun. A multiplicity of views extending through all the phases of these movements, when successively presented in order, before a magic lantern projecting apparatus, gives to the eye the striking semblance of real movements. In practice these views are taken by special cameras, and are printed on long transparent ribbons that contain many hundreds, and even thousands of the views. Edison’s Kinetoscope is covered by patent No. 493,426, March 14, 1893, and his instrument known as the Vitascope, is one of those used for projecting the views upon a screen. In Fig. 201 a similar instrument, called the Biograph, is shown, in which the seeming approach of the locomotive makes those who witness it shudder with the apparent danger.
To secure the best results, the ribbon with its views should remain with a figure the longest possible time between the light and the lens, and the shifting to the next view should be as nearly instantaneous as possible. This problem has been admirably solved by C. F. Jenkins, who, in 1894, devised means for accomplishing it, and was one of the first, if not the first, to successfully project the views on a large screen adapted to public exhibitions. His apparatus is shown in Fig. 202. An electric motor, seen on the left, drives, through a belt and pulley, a countershaft, and also through a worm gear turns another shaft parallel to the countershaft, and bearing a sprocket pulley, whose teeth penetrate little marginal holes in the ribbon of views, and, drawing it down from the reel above, deliver it to the receiving reel on the right. On the end of the countershaft, just in front of the sprocket wheel, is a revolving crank pin or spool, which intermittently beats down the ribbon of views, causing the latter to advance through the vertical guides in front of the lens by a succession of jerks. This holds each view for a maximum period before the lens, and then suddenly jerks the ribbon to bring the next view into position. In the Kinetoscope the animated pictures not only present the movements of life, but, by a combination with the phonograph, the audible speech, or music fitting the occasion, is also presented at the same time, making a marvelous simulation of real life to both the eye and the ear.
Among the latest promises of the inventor is the “Distance Seer,” or telectroscope, which, it is said, enables one to see at any distance over electric wires, just as one may telegraph or telephone over them. The surprises of the Nineteenth Century have been so many and so astounding, and the principles of this invention are so far correct, that it would be dogmatic to say that this hope may not be realized.
To the sum total of human knowledge no department of science has contributed more than that of optics. With the telescope man has climbed into the limitless space of the heavens, and ascertained the infinite vastness of the universe. The flaming sun which warms and vitalizes the world, is found more than ninety millions of miles away. The nearest fixed stars visible to the naked eye are more than 200,000 times the distance of the sun, and their light, traveling at the rate of 190,000 miles a second, requires more than three years to reach us. Although so far away, their size, distance, and constitution have been ascertained, and their movements are scheduled with such accuracy that the going and coming thereof are brought to the exactness of a railroad time table. The astronomer predicts an eclipse, and on the minute the spheres swing into line, verifying, beyond all doubt, the correctness of the laws predicated for their movements. The wonders of the telescope, the microscope, and the spectroscope are, however, but suggestions of what we may still expect, for science abundantly teaches that the eye may yet see what to the eye is now invisible, and that light exists in what may now seem darkness.
No man may say with certainty what thought was uppermost in Goethe’s mind when, grappling in the final struggle with the King of Terrors, he exclaimed ““Mehr licht!”” It may be that it was but the wish to dispel the gathering gloom of his dimming senses, or perchance the unfolding of an illuminated vision of a brighter threshold, but certain it is that no words so voice the aspirations of an enlightened humanity as that one cry of “More light!”
Experiments of Wedgewood and Davy—Niépce’s Heliography—Daguerre and the Daguerreotype—Fox Talbot Makes First Proofs from Negatives—Sir John Herschel Introduces Glass Plates—The Collodion Process—Silver and Carbon Prints—Ambrotypes—Emulsions—Dry Plates—The Kodak Camera—The Platinotype—Photography in Colors—Panorama Cameras—Photo-Engraving and Photo-Lithography—Half Tone Engraving.
““Art’s proudest triumph is to imitate nature.””
When nature paints she does so with the brush of beauty, dipped in the pigment of truth. The tender affection of a ray of light touches the heart of a rose, brings a blush to its cheek, and life, becoming the bride of chemical affinity, blooms into surpassing beauty and loveliness. Photography is closely allied to nature’s painting, for just as light brings into existence nature’s living beauties, so does light fix, preserve, and perpetuate these beauties by the same subtile and mysterious agency of a quickened chemical affinity. Photography is both an art and a science, and as such is both beautiful and true. It is an art intimately associated with the tenderest affections of the human heart in keeping alive its precious memories. By it the youthful sweetheart of long ago, the loving face of the departed mother, and the cherished form of the dead child are brought back to us in familiar presence, while our great men have become the every-day friends and ideals of the common people. What an enrichment and satisfaction it would have added to our lives if the art had been coeval with history, and all the world’s exalted scenes and faces had come to us through the camera with the knowledge of absolute truth and fidelity. But not only in portraiture is photography a great art, for it catches the stately pose of the mountain, the grandeur of the sea, the beauty of the forest, or the majesty of Niagara Falls, and brings them all home to us, even to the vision of the bed-ridden invalid. The camera alike records the secrets of the starry heavens and the bacteria of the microscopic world. Hanging on the tail of a kite it photographs the face of mother earth, and, acting quicker than the lightning, it catches and defines the path of that erratic flash. It plays the part of a private detective, and its testimony in court is never doubted. The architect, engineer, and illustrator find it in constant requisition. By the aid of the Roentgen Rays, it locates a bullet in a wounded soldier, and takes a picture of one’s spinal column. In fact, it sees and records things both visible and invisible, acts with the rapidity of thought, and is never mistaken.
The art of photography, named from the two Greek words φωτος γραφη (the writing of light), is a comparatively new one, and belongs entirely to the Nineteenth Century. It was known to the ancient alchemists that “horn silver” (fused chloride of silver) would blacken on exposure to light, but there was neither any clear understanding of the nature of this action, nor any application made of it prior to the year 1800. We now know that the art of photography is dependent upon the actinic effect of certain of the rays of the spectrum upon certain chemical salts, notably those of silver and chromic acid, in connection with organic matter. The rays which have this effect are the blue and violet rays at one end of the spectrum, and even invisible rays beyond the violet, the red and yellow rays having little or no such actinic effect.
That which made photography possible for the Nineteenth Century was the philosophical observation of Scheele, in 1777, upon the decomposing influence of light on the salts of silver, and the superior activity of the violet rays of the spectrum over the others in producing this effect. In 1801 Ritter proved the existence of such invisible rays beyond the violet end of the visible spectrum by the power they possessed of blackening chloride of silver.
Earliest Application of Principles.—The first attempt to render the blackening of silver salts by light available for artistic purposes, was made by Wedgewood and Davy in 1802. A sheet of white paper was saturated with a solution of nitrate of silver, and the shadow of the figure intended to be copied was projected upon it. Where the shadow fell the paper remained white, while the surrounding exposed parts darkened under the sun’s rays. There was, however, no means of fixing such a picture, and in time the white parts would also turn black.
Introduction of Camera.—The camera obscura, a very old invention designed for the use of artists in copying from nature, was at a very early period brought into this art, but it was found that the chemicals employed by Wedgewood and Davy were not sufficiently sensitive to be affected by its subdued light. In 1814, however, Joseph Nicéphore Niépce, of Chalôns, invented a process that utilized the camera, and which was called “Heliography,” or sun drawing. In 1827 he discarded the use of silver salts, and employed a resin known as “Bitumen of Judea” (asphaltum). A plate was coated with a solution of this resin and exposed. The light acting upon the plate rendered the resin insoluble where exposed, and left it soluble under the shadows. Hence, when treated with an oleaginous solvent the shadows dissolved out, and the lights, represented by the undissolved resin, formed a picture, which was in reality a permanent negative. The process, however, was slow, requiring some hours.
The Daguerreotype.—In 1829 Niépce and Daguerre became partners, and in 1839, after the death of the elder Niépce, the process named after Daguerre was perfected (British patent No. 8,194, of 1839). He abandoned the resin as a sensitive material, and went back to the salts of silver. He employed a polished silver surfaced plate, and exposed it to the action of the vapors of iodine, so as to form a layer of iodide of silver upon the surface, which rendered it very sensitive. By a short exposure in the camera an effect was produced, not visible to the eye, but appearing when the plate was subjected to the vapor of mercury. This process reduced the time required from hours to minutes, and as it involved the production of a latent image, which was subsequently developed by a chemical agent, it represented practically the beginning of the photographic art as practiced to-day. Daguerre sought also to permanently fix his pictures, but this was accomplished only imperfectly until 1839, when Sir John Herschel made known the properties of the hyposulphites for dissolving the salts of silver. In 1844 Hunt introduced the protosulphate of iron as a developer.
Production of Positive Proofs from Negatives.—This was first done by Mr. Fox Talbot, of England, between 1834 and 1839. In his first communication to the Royal Society, in January, 1839, it was directed that the paper should be dipped first in a solution of chloride of sodium, and then in nitrate of silver, which, by reaction, produced, on the face of the paper, chloride of silver, which was more sensitive to the light than nitrate of silver. The object to be reproduced was laid in contact with the prepared paper, and exposed to the light until a copy was produced which was a negative, having the lights and shadows reversed. A second sheet was then prepared, and the first or negative impression was laid upon it, and used as a stencil to produce a second print which, by a reversal of the lights and shadows, formed an exact reproduction of the original. In 1841, British patent No. 8,842 was obtained by Mr. Talbot, for what he called the “Calotype,” and which was afterward known as the “Talbotype.” A sheet of paper was first coated with iodide of silver, by soaking it alternately in iodide of potassium and nitrate of silver, and was then washed with a solution of gallic acid containing nitrate of silver, by which the sensitiveness to light was increased. An exposure of some seconds or minutes, according to the brightness of the light, produced an impression upon the plate, which, when treated with a fresh portion of gallic acid and nitrate of silver, developed into the image. After being fixed it formed a negative from which any number of prints might be obtained. The Talbot process represented a great advance in this art. Glass plates to retain the sensitive film were introduced by Sir John Herschel in 1839, and were a great improvement over the paper negatives, which latter, from lack of transparency and uniformity in texture, had prevented fine definition and sharpness of outline. Blue printing was also invented by Sir John Herschel in 1842, and he was the first to apply the term “negative” in photography. In 1848 M. Niépce de St. Victor, a nephew of Daguerre’s former partner, applied to the glass a film of albumen to receive the sensitive silver coating.
Collodion Process.—The most important step in the preparation of the negative was the application of collodion. This is a solution of pyroxilin in ether and alcohol, which rapidly evaporates and leaves a thin film adhering to the glass. M. Le Gray, of Paris, was the first to suggest collodion for this purpose, but Mr. Scott Archer, of London, in 1851, was the first to carry it out practically. A clean plate of glass is coated with collodion sensitized with iodides of potassium, etc., and is then immersed in a solution of nitrate of silver. Metallic silver takes the place of potassium, forming insoluble iodide of silver on the film. The plate is then exposed and the latent image developed by an aqueous solution of pyrogallic acid, or protosulphate of iron. When sufficiently developed, the plate is washed, and the image fixed by dissolving the unacted-upon iodide of silver with a solution of cyanide of potassium or hyposulphite of soda. This completed the negative or stencil from which the positives are printed by passing rays of light through it upon sensitive paper.
The Ambrotype succeeded the Daguerreotype, and was produced by making a very thin negative by under exposure on glass, using the collodion process, and, after drying, backing the glass with black asphaltum varnish or black velvet, causing the dense portions of the negative to appear white by reflected light, and the transparent portions black. Such pictures were quickly made, and were much in vogue forty years ago, but are now obsolete. A modification of the ambrotype, however, still survives in what is known as the “tin-type” or “ferro-type.” In the tin-type the collodion picture is made directly upon a very thin iron plate, covered with black enamel, which both protects the plate from the action of the chemicals in the bath, and forms the equivalent of the black background of the ambrotype.
Silver Printing.—A sheet of paper, previously treated with a solution of chloride of sodium and dried, is sensitized in an alkaline bath of nitrate of silver. When the paper is exposed under a negative, the light through the transparent parts of the negative reduces the silver, converting the chloride, it is supposed, into a metallic sub-chloride of silver which becomes dark or black, and constitutes the main portion of the picture. The image is then fixed by dissolving out the chloride of silver unaltered by light in a bath of hyposulphite of soda. After fixation, the image is well washed in several changes of water to eliminate all traces of the hyposulphite of soda and prevent the subsequent fading of the darkened portions of the picture and the yellowing of the whites. If the printed image is immediately fixed, it will have a red color. To avoid this it is washed first in water and then immersed in a chloride of gold toning bath and fixed.
The Platinotype Process is one in which potassium chloroplatinite and ferric oxalate are converted by light into the ferrous state, and metallic platinum is reduced when in contact with the ferrous oxalate of potash solution. The unacted upon portions are dissolved out by dilute hydrochloric acid, leaving a black permanent image. This process is characterized by simplicity, sensitiveness in action, permanence of print, and a peculiarly soft and artistic quality in the picture. British Patent No. 2,011, of 1873, to Willis, is the first disclosure of the platinotype.
Carbon Printing is a process in which lampblack or other indestructible pigment is mixed with the chemicals to render the photograph more stable against fading from the gradual decomposition of its elements. Mungo Ponton, in 1838, discovered the sensitive quality of potassium bichromate, which led up to carbon printing. Becquerel and Poitevin, in Paris, in 1855, were the first to experiment in this direction, and Fargier, Swan, and Johnson were successors who made valuable contributions.
Emulsions.—A photographic emulsion is a viscous liquid, such as collodion or a solution of gelatine, containing a sensitive silver salt with which the glass plate is at once coated, instead of coating the plate with collodion or gelatine, and then immersing it in a sensitizing bath. The desirability of emulsions was recognized as early as 1850 by Gustave Le Gray, and in 1853 by Gaudin. Collodion emulsion with bromide of silver was invented by Sayce and made known in 1864. In 1871 Maddox published his first notice of gelatine emulsion, and in 1873 the gelatine emulsions of Burgess were advertised for sale. In 1878 Mr. Charles Bennett brought out gelatino-bromide emulsion of extreme sensitiveness, by the application of heat, and from this time gelatine began to supersede all other organic media.
Dry Plates were a great improvement over the old wet process, with its tray for baths, its bottles of chemicals, and other accessories. Especially was this the case with out of door work, which heretofore had involved the carrying along of much unwieldy and inconvenient paraphernalia. With the dry plate process only the camera and the plates were needed, and this step marks the beginning of the spread of the art among amateurs, and the great snap-shot era of photography, growing into a distinct movement about the year 1888, has since spread over the entire world. The first practical dry plate process (collodion-albumen) was published in 1855 by Dr. J. M. Taupenot, a French scientist. Russell, in 1862; Sayce, in 1864; Captain Abney, for photographing the transit of Venus in 1874; Rev. Canon Beechey, of England, in 1875; Prof. John W. Draper, of the University of New York, and the Eastman Walker Company, of Rochester, were the chief promoters of dry plate photography. The practical introduction began about 1862 with the application of the alkaline developer.
The progress of the photographic art may be approximately noted as follows:
| Process. | Time Required. | Introduced. | |
|---|---|---|---|
| Heliography | 6 | hours’ exposure | 1814 |
| Daguerreotype | 30 | minutes’ exposure | 1839 |
| Calotype or Talbotype | 3 | minutes’ exposure | 1841 |
| Collodion process | 10 | seconds’ exposure | 1851 |
| Collodion emulsion (dry plate) | 15 | seconds’ exposure | 1864 |
| Gelatine emulsion (dry plate) | 1 | second exposure | 1878 |
Mechanical Development.—The photographic camera is but an adaptation of the optical principles of the old camera obscura, which has been credited to various persons, including Roger Bacon in 1297, Baptista Porta about 1569, and others. The essential elements of the camera obscura are a dark chamber, having in one end a perforation containing a lens, and opposite it on the back of the chamber a screen upon which an image of the object is projected by the lens for the purpose of enabling it to be directly traced by a pencil. The photographic camera, introduced by Daguerre in 1839, adds to the camera obscura some means for adjusting the distance between the lens and the screen on which the image falls. This was accomplished by making the dark chamber adjustable in length by forming it in two telescopic sections sliding over each other, and in later years by the well-known bellows arrangement. A luminous image of any object placed in front of the lens is thrown in an inverted position upon the screen, which is of ground glass, to permit the image to be seen in focusing. When the proper focus on this ground glass is obtained a sensitive plate is put in the plane of this screen to receive the image.
It is not possible to trace all the steps of development of the camera which have brought it to its present perfection. Most of the improvements have had relation to the lens in correcting chromatic and spherical aberration, and in shutters for regulating exposure, in stops for shutting out the oblique rays and holders for the sensitive plate.
The “Iris” shutter, so-called from its resemblance in function to the iris of the eye, consists of a series of tangentially arranged plates which open or close a central opening symmetrically from all sides.
The ordinary camera of the photographic artist is too familiar an object to require special illustration. It has been looked into by the rich and the poor, and the high and the low, all over the whole world. Between the traveling outfit, and the “look pleasant, please!” of the peripatetic artist, and the handsome studios of the cities, it is hard to find an individual in the civilized world who has not posed before its lens. Through its agency the great man of the day has found himself in evidence everywhere; the country maiden has many times experienced the delicious thrill of satisfied vanity as she posed before it, and the superstitious savage is paralyzed with fear lest the mysterious thing should steal his soul.
In 1851 the first instantaneous views were made by Mr. Cady and Mr. Beckers, of New York, and also by Mr. Talbot, who employed as a flash light a spark from a Leyden jar. In 1864 magnesium light was employed by Mr. Brothers, of Manchester, for photographic purposes, and about 1876-8 Van der Weyde made use of the electric light for the same purpose.
The roller slide, or roll film, was invented by A. J. Melhuish, in England, in 1854 (British patent No. 1,139, of 1854). The films were, however, of paper. In 1856 Norris produced sensitized dry films of collodion or gelatine (British patent No. 2,029, of 1856). In later years apparatus for utilizing the roll film has been greatly improved and extensively applied by Eastman, Walker & Co., of Rochester, N. Y.
About 1888 a new thing in the photographic world made its appearance. It was a little black leather-covered rectangular box, about six inches long, with a sort of blind eye at one end closed by a cylindrical shutter, substantially as seen in Fig. 203. This shutter was wound up by a spring operated by a pull cord. In the back of the box was a film or ribbon of sensitized paper wound upon one spool, and unwinding therefrom and winding onto another spool, and being distended as it passed so as to form a flat surface which was directly in rear of the lens. A thumb piece or key on the top, and a push button on the side, were the only suggestions of the operative mechanism within. When the button was pressed the shutter for an instant passed from in front of the lens, and as quickly covered it again, but in this brief interval an image had been flashed upon the sensitive ribbon or film, and a snap-shot picture was taken. By a simple movement of the thumb piece or key, the receiving roll was made to take up the exposed section of the sensitive film and bring another section into the range of the lens, for a repetition of the operation. This little instrument was slung in a case looking like a cartridge box, and its sensitive roll was able to receive 100 successive pictures. When the roll was exhausted, it was removed and developed in a dark room. The device was placed upon the market by the Eastman Company, and it was called the “Kodak.” The advertisement of the company, that “You press the button and we do the rest,” was soon realized to be founded in fact, and in a short while the great era of snap-shot photography had set in. To-day this form of camera is a part of the luggage of every tourist, traveler, scientist, and dilletante. In fact, it has become the familiar scientific toy of man, woman, and child, interesting, instructive, and useful to all. In Fig. 204 is shown a modern form of Kodak, which is made in various sizes and is foldable for compact and convenient portability.
A very convenient and useful development in films is to be found in the cartridge system, by which the film may be placed in and removed from the camera in broad daylight. The film has throughout its length a backing of black paper which extends far enough beyond the ends of the film to allow it to be unwound, so far, in making connection with the roll holder, without exposing the film to light, and also to allow it to be removed without exposure to light, after all the exposures have been made.
Among the many other ingenious and useful hand cameras may be mentioned the “Premo,” made by the Rochester Optical Company, and shown in Fig. 205. The “Premo” is arranged for either snap-shot or time exposure, is adapted to be either held in the hand or mounted upon a tripod, and is furnished for use either with glass plates or roll films. In Fig. 206 is shown the “Premo” for stereoscopic work, in which two pictures are taken at once, a sufficient distance from each other to produce the effect of binocular vision and give the appearance of relief when viewed through the stereoscope. Brett’s British patent No. 1,629, of 1853, appears to be the earliest description of a stereoscopic camera.
There have been 2,000 United States patents granted in photography, most of which have been taken in the past thirty years, and great efficiency and detail in both the chemical and mechanical branches of the art have been obtained.
The useful applications of the art have been numerous and varied. Portrait making is probably the largest field. This was first successfully accomplished in 1839 by Professor Morse, of telegraph fame, working with Prof. John W. Draper, of the University of New York.
Celestial Photography began with Prof. Draper’s photograph of the moon in March, 1840, and Prof. Bond, of Cambridge, Mass., in 1851. In 1872 Prof. Draper photographed the spectra of the stars, and in 1880-81 the nebulæ of Orion, and in 1887 the Photographic Congress of Astronomers of the World, organized in Paris, began the work of photographing the entire heavens. In late years notable work has been done at the Lick Observatory by Prof. Holden. In 1861 Mr. Thompson, of Weymouth, photographed the bottom of the sea, and Prof. O. N. Rood, of Troy, N. Y., the same year described his application of it to the microscope. In 1871 criminals were ordered to be photographed in England, and in America the Rogues’ Gallery became an institution in New York as early as 1857, ambrotypes being first used. In 1876 the Adams Cabinet for holding and displaying the photos was invented. To-day the New York collection amounts to nearly 30,000, while that of the National Bureau of Identification at Chicago approximates 100,000. It is a striking illustration of the law of compensation that the counterfeiter who invokes the aid of photography to copy a bank note is, by the same agency of his photo in the Rogues’ Gallery, identified and convicted.
Photography in Colors has been the goal of artists and scientists in this field for many years. Robt. Hunt, in England, in 1843, and Edmond Becquerel, in France, in 1848, made evanescent photographs in colors, but little progress was made until about the last decade of the Nineteenth Century. Franz Veress in 1890, F. E. Ives (United States patent No. 432,530, July 22, 1890), W. Kurtz (United States patent No. 498,396, May 30, 1893), Gabriel Lippmann in 1892 and 1896, Ives in 1892, M. Lumière in 1893, Dr. Joly in 1895, M. Villedien Chassagne, and Dr. Adrien, M. Dansac and M. Bennetto, all in 1897, represent active workers in this field.
Among recent developments of the camera may be mentioned the wide angle lens, which permits larger images to be made on the plate from small near-by objects, and the telephotographic camera, which gives a large image of remote objects, such as an enemy’s fort, and the panorama camera, which is designed to cover a broad field. For this purpose the lens is movably mounted for a semi-circular swing, and the image is flashed across a curved film in the case. The Eastman Panoram-Kodak, seen in Fig. 207, is an external illustration of this type, and in Fig. 207A is shown a sectional view of another make of panorama camera which clearly shows the internal construction.
As allied branches of the photographic art, photo-engraving, photo-lithographing, and half-tone engraving are important developments of the Nineteenth Century.
Photo-engraving is a process by means of which photographs may be used in forming plates from which prints in ink can be taken. The process depends upon the property possessed by bichromate of potassium, and other chemicals, of rendering insoluble under the action of light, gelatine or some similar substance. A picture is thus produced on a metal plate, and the blank spaces are etched out by acid, leaving the lines in relief as printing surfaces. When the operation is reversed, and only the darks are etched in intaglio, to be filled with ink, as in copper-plate engraving, it is called photo-gravure. Mungo Ponton, in 1839, discovered the sensitive quality of a sheet of paper treated with bichromate of potash. In 1840 Becquerel discovered that the sizing had an important function, and Fox Talbot, in 1853, discovered and utilized the insolubility of gelatine exposed to light in presence of bichromate of potash. In 1854 Paul Pretsch observed that the exposed parts of the gelatine did not swell in water. One of the first suggestions of photo-engraving appears in the British patent No. 13,736, of 1851, of James Palmer. In recent times great perfection in details has been obtained by Mr. Moss, of the Photo-Engraving Company, and others. The Albert-type and Woodbury-type are early modifications of this art.
In photo-lithography the photograph is transferred to the stone, and the latter then used to print from, as in lithography. The operation consists: 1, in making the photographic negative; 2, printing with it upon transfer paper coated with gelatine and bichromate of potash: 3, the transfer paper is then given a coat of insoluble fatty transfer ink from an inking stone; 4, all ink on surfaces not reached by the light being on a soluble surface is washed off, leaving the insoluble lines acted upon by light forming the picture; 5, the washed transfer sheet is then applied to the stone, and the remaining inked lines of the design are transferred to the stone; 6, the stone with transferred lines will now receive ink from the ink rolls on these lines, and repels ink from all other surfaces, which latter are made repellent by being kept constantly wet, as in ordinary lithography. The first attempts in this art were by Dixon, of Jersey City, and Lewis, of Dublin, in 1841, who used resins. Joseph Dixon, in 1854, was the first to use organic matter and bichromate of potash upon stone to produce a photo-lithograph. In 1859 J. W. Osborne patented in Australia, and in 1861 in the United States, a transfer process which gave such great impetus to the art that he may be considered its founder and chief promotor. His United States patents are No. 32,668, June 25, 1861, and No. 33,172, August 27, 1861.
For photo-lithography only line drawing, type print, or script, without any smooth shading, can be employed. The most extensive application of photo-lithography is in the reproduction of the Patent Office drawings, which amount to about 60,000 sheets weekly. The contracting firm, which is probably the largest in the world, also prints each week by photo-lithography 7,000 copies of the Patent Office Gazette, of about 165 pages each, including both drawings and claims, and also reproduces specifications without errors or proof reading, thus saving about 200 per cent. in cost over type setting. This art is also largely employed for printing maps, and the reproduction of the pages of books by this process has flooded the stores and news stands with cheap literature.
Half-tone engraving enables a photograph to be reproduced on a printing press, and for faithfulness in reproduction and low cost has revolutionized the art of illustrating, as nearly all books, magazines, and newspapers are now illustrated by this process. Before its introduction it was not possible to reproduce cheaply in printers’ ink shaded pictures like photographs, brush drawings, paintings, etc. Half-tone engraving renders it possible to thus print on a press, with printers’ ink, reproductions of photographs or any shaded picture, in which the soft shadows fade away in depth to white by an imperceptible tenuity. It does so by breaking up the soft shadows into minute stipples which form inkable printing faces in relief, by the interposition of a fine reticulated screen between the camera lens and the sensitive plate. This forms a sort of stencil negative through which the copper plate is etched, which latter is thus converted into a relief plate whose raised surfaces left by the etching may receive ink and print like an ordinary relief plate. By making the screen lines very fine (80 to 250 meshes to the inch), the visible effect of the shading is so far preserved that the photograph may be reproduced in printers’ ink with but little depreciation. At first, bolting cloth was used for the screen, but at present two glass plates, with closely ruled lines, laid crosswise upon each other, form the screen. A characteristic distinction of half-tone work is the regularly stippled surface, formed by the stenciling out of a portion of the picture by the screen, which may be easily seen with any magnifying glass. It is called half-tone process because half of the tones or shadows are preserved, the other half being stenciled out. The use of gauze screens was first described by Fox Talbot in British patent No. 565, October 29, 1852.
In the making of a half-tone negative, the photograph, painting, or wash drawing which is to be reproduced, is set up in front of the camera, which is arranged on an inclined runway, as seen in Fig. 208, and an exposure is made on a plate prepared by the wet collodion process (see page 304). The shadows of the picture are broken up into stipples or dots by the interposition of a cross-lined screen arranged in the plate holder between the lens and the sensitive plate, so that the picture taken is “half-toned” or stippled. Fig. 209 illustrates the relation of the parts, in which the picture to be copied is seen on the right, the camera lens in the middle, and the cross-lined screen on the left in front of the sensitive plate.
The image on the plate is then developed and fixed, and in order to secure a printed image exactly like the copy as to right and left position it is necessary to reverse the negative. This is done by cutting the film square, as seen in Fig. 210, and then peeling it off the glass, as seen at Fig. 211, and transferring it to another glass plate in reversed relation. The copper printing plate is produced as follows: The plate is first polished, as seen at the top of Fig. 213, and is then sensitized with a solution of organic matter and an alkaline bichromate. The face of the reversed negative is laid flat against and in direct contact with the face of the sensitized copper plate, and tightly held thereto by the screw clamps of the half tone printing frame. The printing on the sensitized copper face through the stippled or half-tone negative is then effected either by daylight or by the electric light. The application of the electric light for this purpose is shown in Fig. 212. The copper plate is then taken out and subjected to the three lower operations seen in Fig. 213. It is first developed under a stream of water from a faucet, seen on the left, and is then taken in a pair of pliers and held over a gas stove, as seen at the bottom, to “burn-in” the image, and then placed in a tray containing an etching bath of chloride of iron seen on the right, by which the copper is eaten away around the little stipples, and the latter, representing the half tones of the original picture, are left raised, or in relief, to form the inkable surfaces of the printing plate. So fine are these stipples, however, that the picture is to the eye perfectly reproduced. The several views illustrating this process are made in this way, the lines of the reticulated screen being 175 to the inch. The plate is next subjected to the mechanical operation of “routing out” or cutting away the undesirable portions by a routing machine, seen in Fig. 214. It then receives further mechanical treatment to correct imperfections and finish its edges, and is finally mounted upon a block ready for the printer.
The most striking application made of photography in recent years is in the production of so-called moving pictures, in which a series of photographic figures thrown upon the screen have all the motion of animated scenes which have been caught and imprisoned by the swiftly acting and never failing memory of the camera, to be again turned loose in active play through the Kinetoscope or Biograph. Perhaps the most valuable contribution to science at the end of the century made by this art is in surgery, for photographing through opaque bodies by the aid of the Roentgen rays, but for the latter subjects treatment in separate chapters must be reserved.