An Encyclopedia of the History of Technology part 76 doc

PART FOUR: COMMUNICATION AND CALCULATION 732 Judaea dissolved in animal oil, coated on to sheet of glass, copper or pewter. He made a sandwich of engraving, sensitized plate, and a sheet of glass, which he exposed to the sun for two to four hours, which hardened the exposed varnish. Then, in a darkroom, he immersed the plate in an acid bath to dissolve the varnish protected by the lines of the engraving; the remaining hardened varnish formed the image. He called this process, as well as the images he made in a camera obscura, heliography. The earliest known such image is a view of neighbouring rooftops made by exposing a pewter plate in a camera obscura for eight hours: because of this extremely lengthy exposure of the first true photograph, the sun can be seen lighting both sides of the rooftops. Niepce soon changed his material to silver-plated copper, and gave the plates extra sensitivity by iodine fuming. He also tried glass plates, viewing them as transparencies, so it is surprising that he did not realize he could use these as negatives to make multiple prints—the basis of most modern photography. This invention was not made until 1835, by Henry Fox Talbot in England. In a camera obscura, he exposed a sheet of paper which had been sensitized with silver chloride. The first such negative he made was of a window in his home, Lacock Abbey in Wiltshire. Unlike the plates of Niepce, Fox Talbot’s process required an exposure of only thirty minutes. Sir John Herschel, who named the invention ‘photography’ and also coined the terms ‘negative’ and ‘positive’, suggested removing the unexposed silver chloride to fix the image permanently, using hyposulphite of soda. With its name shortened to hypo, this is still the standard fixing solution. In 1840, Talbot discovered (as had Daguerre two years before) that an exposure of only a few minutes could provide a latent image, which could be developed by chemical means afterwards. Fox Talbot used gallic acid as a developer, and after drying the paper negative, made it transparent by a wax coating. Then he contact printed it on to another sheet of silver-chloride paper to make a positive; he called this process calotypy. The first person to make a commercial success of photography was Louis- Jacques-Mande Daguerre in France in 1839. He based his invention on Niepce’s process, but brought out the latent image with mercury vapour and fixed it permanently with a hot solution of table salt. The resulting image was a positive which could be viewed only by reflection at certain angles, but the quality of the images was superb and many have lasted to the present time. As an artist-showman, Daguerre had created his Diorama in 1822 in Paris, with 14× 22m (46×72ft) painted canvases; therefore, he was well placed to exploit his invention commercially. However, subjects for portraiture found it torture to sit under a baking sun for 10 to 20 minutes. Soon, the 6 1/2 by 8 1/2 inch (16.5× 21.5cm) plate was reduced to quarter-size, bringing exposure time down to a few minutes. Then, by the use of large aperture achromatic lenses, and by enhancing the mercury vapour with bromine and chlorine, exposure INFORMATION 733 time was reduced to thirty seconds, and portraits for everyone became a reality. The craze for daguerreotypes, as they were called, spread rapidly from Europe to the United States, and dominated the profession for decades. A Scottish painter, David Octavius Hill, and a chemist-photographer, Robert Adamson, made 1500 superb pictures between 1843 and 1848 using Talbot’s calotype paper-negative process. In 1848, Niepce de Saint-Victor developed a system using a glass plate coated with a solution of iodized albumen, and sensitized with silver nitrate. Then L.D.Blanquart-Evrard coated paper with albumen to make positives, eliminating much of the paper’s inherent roughness. Blanquart-Evrard established the first mass-production photographic printing plant in Lille, France. He employed forty girls, each of whom performed one specialized operation. In 1851 he published the first album of original photographs, and the following year the first book illustrated with them. Frederick Scott Archer, a British sculptor and photographer, invented the wet collodion process in 1851, displacing the calotype and daguerreotype as the most popular photographic medium until the dry-plate process was introduced by R.L.Maddox in the 1870s. Scott Archer made collodion by dissolving guncotton, ether and alcohol, blending it with a solution of silver and iron iodides. This was applied to a glass plate, which was then immersed in a silver nitrate solution and exposed wet in the camera; the plate had to be developed while the collodion remained moist, giving the photographer only ten minutes after the exposure to develop the plate. This was physical development: silver was deposited to make the latent image visible, and then it was fixed in sodium cyanide. The great advantages of the wet collodion process were that exposure required only two to three seconds, and its tonal range was greater than that of other existing processes. However, a photographer in the field had to carry more than 50kg of equipment with him, including cameras, distilled water, chemicals, plates, trays, and even a darkroom. Nevertheless, the process provided the first portable photographic system, which made possible the magnificent portraits and landscapes of such pioneering photographers as Bisson Frères (the Alps, 1860); Roger Fenton (the Crimean War, 1855); William Notman (the Canadian north, early 1860s); Nadar (portraits; first aerial photographs, 1862); Julia Margaret Cameron (portraits, 1860s to 1870s); and Mathew Brady (American Civil War, 1860s). Microphotography The processes of Daguerre and Scott Archer exhibited very high resolution, that is, the ability to capture fine detail. In 1839, J.B.Dancer, an optical instrument maker from Liverpool and Manchester, made the first PART FOUR: COMMUNICATION AND CALCULATION 734 microphotograph. (Microphotography is the copying of objects on a very reduced scale, in contrast to photomicrography, which is the recording of the enlarged image of an object under a microscope.) He made his microphotographs in a daguerreotype camera fitted with a 1 1/2-inch (3.8cm) microscope lens, and attained the remarkable reduction of 160:1 (linear). Dancer’s invention gave birth to the document recording segment of the photographic industry, now called microrecording or micrographics. Early uses were more trivial. By 1859, a fashion began which featured 1/16 to 1/8-inch (1.5–3mm) microphotographs incorporated into jewellery and domestic items. The tiny transparencies were glued in contract with a jewel lens called a Stanhope. It is said that certain immodest subjects exhibited in this way brought the art of photography into disrepute. Sir David Brewster was the first to suggest using microphotographs to communicate dispatches in wartime. However, this was not done until 1870–1, when Dagron, who had established a studio in Paris for the manufacture of miniature photographic novelties, found his business ruined by the Franco- Prussian War. With Paris itself under siege, carrier pigeons sent out in balloons provided the only means of communication over enemy lines. However, a pigeon could only carry a tiny piece of paper. Dagron escaped to Tours in a balloon with his equipment and an assistant. There he devised a system in which all private and public letters were printed on large sheets of paper, each of which could hold 300,000 characters—the equivalent of about 100 typewritten pages today. These sheets were photographically reduced on to thin collodion films, each 50×70mm (2×2 3/4in); twenty of these could be rolled into a quill. Flown by pigeon to Paris, they were projected on to a large screen and transcribed by a small army of copyists. A remarkable 100,000 dispatches were sent in this way, forty copies of each being made to ensure that at least one got through. After the war the process languished until an inexpensive material became available early in the twentieth century, the 35mm motion-picture film. Special cameras and emulsions were developed for this purpose, and microfilms of everything from rare books to fragile newspapers and bank cheques are now archived on this strong, long-lived medium with great savings in storage and postage. The idea of the pigeon post was revived in the US during the Second World War: starting in 1942, V-mail service, as it came to be known, was provided between servicemen and their families. Letters written on special blanks were photographed on to 16mm microfilm, which was sent overseas by airmail; the received images were enlarged on to rolls of photographic paper, cut into individual letters, and folded for mailing to recipients. Photographic emulsions had been supported by metal plates, then by paper and glass; these materials were in single-sheet form and each had to be handled individually. In 1889, George Eastman, frustrated with the difficulties of the photographer’s lot, invented roll film, and with it simple cameras preloaded INFORMATION 735 with 100 exposures. Amateurs would take ‘snapshots’ and send camera and film to Eastman’s company where they would be developed and printed— ‘You push the button and we do the rest’. With Eastman, and his company Kodak, photography became an industry with a mass market. Stereoscopy No matter how realistic early photographic images seemed, they lacked two essentials of nature: colour and depth. The illusion of depth was made possible with the invention of the stereoscope by Sir Charles Wheatstone in 1838. He created a device to present a pair of perspective drawings, one as seen by the left eye alone and the other by the right eye. However, this created little interest until photography made the recording of stereoscopic views quick and easy; Fox Talbot made calotypes of still-life for some of the first stereoscopes. In 1849, Sir David Brewster invented a stereoscope with two magnifying lenses 7cm (2.75in) apart, corresponding to the distance between the two eyes. Not finding an English optician to manufacture and market the device, he took it to Jules Duboscq in Paris. At the Great Exhibition of 1851, the Duboscq and Soleil stereoscope was exhibited using a collection of daguerreotype stereo images to great acclaim. However, daguerreotypes were not the best medium for stereoscopy because their shiny surfaces could only be viewed at certain angles. Brewster also invented a stereoscopic camera in 1849, but it was not manufactured until 1853; until then, it was necessary to use two cameras side by side, or one camera which could be moved sideways. The stereoscope enjoyed great success; by 1860, hundreds of thousands of stereographs of subjects from all over the world were available. Oliver Wendell Holmes was an enthusiastic user, and designed a hand-held stereoscope which became standard. Interest in stereoscopic photography has waxed and waned ever since, but the need to use special cameras, viewers and projectors has kept it from becoming as popular as conventional photography for all but the dedicated amateur. Colour photography The mixing of a few primary-colour pigments to make the vast array of colours we see was known to painters for centuries, but colour photography had to wait until James Clerk Maxwell in 1855 showed that there were also light primaries. In 1861 he projected an image of a multi-coloured ribbon using three superimposed colour images. In 1868, Louis Ducos du Hauron in Paris suggested techniques for making colour photographs on paper, and these became the basis for all colour photography for the next 60 years. In 1911–12, PART FOUR: COMMUNICATION AND CALCULATION 736 Fischer proposed an integral tripack, superimposing three emulsion layers, and in 1919, Christenssen suggested dying the layers to separate the colours optically, but the technology available at that time was not up to the task. In the early 1930s two young American musicians, Leopold Mannes and Leopold Godowsky, invented the first practical process based on the integral tripack; they sold it to the Eastman Kodak Company, which placed it on the market under the trade name Kodachrome in 1935. It was first used as 16mm motion picture film, then extended to 8mm, and only later made in 35mm for colour transparencies. Agfacolor, a process based on additive colour combination rather than the subtractive process of Kodachrome, was marketed for 16mm motion pictures by Agfa in Germany in 1936. The professional motion picture industry used Technicolor, a complex, multi-emulsion system using dichroic mirrors, which had originally been developed as a two-colour system in 1918. The first three-colour Technicolor production was Disney’s animated cartoon ‘Flowers and Trees’ (1932); it was not until 1942 that Technicolor introduced a monopack process, reducing the number of negatives from three to one. Electrophotography The photographic process had always involved the use of chemicals, which usually had to be in solution or vapour form; other imaging processes such as television, which were based on electronics, could not provide a fixed image. In 1938 an American patent attorney named Chester Carlson made a crude electrophotograph on his kitchen table. He named his process xerography, because it used a dry powder which clung to those parts of a semiconductive plate which had been electrified. He had great difficulty in trying to bring the invention to market; twenty companies refused to consider it, and he turned to the Battelle Development Corporation for help. In 1947 they finally sold the rights to a small photographic materials company, the Haloid Corporation. After about ten years of development, the first automatic system for making dry images on ordinary paper was marketed, the Xerox 914; the company became the Xerox Corporation, and today rivals Kodak, its Rochester, New York, neighbour which had turned down Carlson, in the multinational industry of image technology. Instant photography The next breakthrough in photography appeared just after the Second World War. Edwin Land, already well known for his invention of Polaroid in the 1930s (the first economical material for polarizing light), put the world’s first instant camera on the market late in 1948. The Polaroid 95 produced sepia- INFORMATION 737 toned prints directly, a finished print being delivered from the camera in just one minute. Then, in 1962, Polaroid brought out Polacolor, which made instant photography in colour a reality. Thus, in little more than a century, the art and science of the image had so progressed that what originally required an artist-scientist with a portable chemical laboratory, could now be accomplished by a child with a hand-held, self-contained box capable of capturing the fleeting moment and producing a permanent record on the spot. Lasers and Holography Light is only a tiny portion—less than 1 per cent—of an electromagnetic spectrum which ranges over more than twenty orders of magnitude, from waves many kilometres long to those of atomic dimensions. Components analogous to optical lenses, mirrors, diffraction gratings, prisms, filters and sensitive materials have been constructed to control and record these waves. Holography is a type of ‘lensless’ photography invented by Denis Gabor in the UK in 1948. It is a process based upon the phenomenon of light interference, allowing both the amplitude and the phase of the propagating waves to be recorded (hence the name holography: ‘recording of the whole’). By this means, true three-dimensional images can be shown; it is possible for an observer literally to walk around the image, seeing it as it would be in reality. Holography remained an interesting, but impractical invention until powerful sources of monochromatic, coherent (meaning that the waves are all in step) radiation were developed. Einstein had postulated the possibility of stimulated emission of radiation in 1917, but it was not until the 1950s that this idea was embodied in a practical device. Fabrikant in the USSR filed for a patent in 1951, but failed in his efforts to use caesium for optical amplification. J.Weber in the US described such possibilities in 1953, and N.G.Basov and A.M.Prokorov of the USSR made detailed proposals for a beam maser (Microwave Amplification by Stimulated Emission of Radiation) the following year. However, Charles H.Townes, a professor of physics at Columbia University, working with his graduate student James P.Gordon and postdoctoral researcher Herbert Zeiger, built the first successful maser in 1954. Townes’s group, working with Arthur L.Schawlow of Bell Telephone Laboratories, thought out a scheme for an optical maser. Gordon Gould, another Columbia graduate student, devised the term laser (Light Amplication by Stimulated Emission of Radiation); he went to work for a defence contractor, TRW, which, proposing his laser ideas to the receptive US Department of Defense’s Advanced Research project Agency, received a million dollars for its development—three times as much as they had requested. All these researchers were concentrating on gaseous systems, hoping to be the first to demonstrate a practical laser. However, it was Theodore H. PART FOUR: COMMUNICATION AND CALCULATION 738 Maiman, working with ruby masers at the Hughes Research Laboratories, who accomplished the feat. Maiman decided to try this gem material because it was rugged and did not have to be used at very low temperatures, even though Schawlow had calculated that ruby could not work. He put a tiny rod of ruby inside the spiral of a photographic flash lamp, and so achieved the first laser emission in 1960. Maiman’s submission of his results was rejected by the editor of Physical Review Letters, so that his first published report appeared in the British journal Nature. A few months later, Townes and Schawlow demonstrated their helium-neon laser, and Townes shared a Nobel prize in 1964 with Basov and Prokhorov for the maser-laser principle. Maiman, who had built the first true laser, did not share in the prize. Holography and the laser exhibit very well the dual nature of light: holography can only be understood by considering light as waves, but lasers are best conceived in terms of light as tiny energy packets—photons. Because holography is a means of recording wave phenomena, not only images made by light may be so captured, but waves from other parts of the electromagnetic spectrum—particularly microwaves; as well as those generated mechanically (by vibration) —particularly water and sound waves. In 1962 several semiconductor lasers were announced in the US, and both the technology and the application of coherent light sources has advanced rapidly ever since. Such diverse systems as the proposed US Strategic Defense Initiative (‘star wars’), thermonuclear fusion power, and telecommunications through fibre optics depend upon lasers. However, the first consumer products to employ lasers are videodisc and compact disc using digital recording techniques, the former being designed for motion-picture and television images and the latter for music (see pp. 753–6). Motion Pictures The motion picture, as we are familiar with it today, is the culmination of a number of inventions, but, even more than still photography, it depends on human physiology and psychology—for it is an optical illusion. The notion of projecting an image on to a screen in a darkened room before an audience is implied in the term ‘camera obscura’. However, up to the middle of the seventeenth century, no one seems to have thought of it in terms of theatre. In 1654, P.Kircher in Germany described a small projector for transparencies and about 1660, Christian Huygens constructed a magic lantern, but such projectors were not manufactured on a large scale until 1845, when they quickly spread throughout Europe. The magic lantern can be thought of as an inside-out camera obscura: instead of projecting a sunlit outdoor scene into a darkened room, it projects scenes drawn on glass slides and placed between a source of light and a lens on to a light-coloured surface. INFORMATION 739 Artificial illumination for the magic lantern progressed rapidly to oil lamps, and then to limelight and electric arc. Light was concentrated by putting a concave mirror behind the light source, and additional (condenser) lenses were added to collimate the light beam before it reached the slide. Several developments which foreshadowed the invention of the motion picture occurred in the nineteenth century, such as the use of multiple lanterns, which allowed one view to dissolve into another, and, between 1850 and 1890, increasingly elaborate mechanisms built into the slides themselves to provide a simulation of motion. Another development which was necessary before motion pictures could become a reality was a flexible transparent film, so that a rapid succession of images could be pulled past the light source. George Eastman’s celluloid film was placed on the market in 1889. The third essential element was an understanding of visual psychophysiology, and how it could be fooled. Of course, magicians had always depended on the dictum that ‘the quickness of the hand deceives the eye’, but it was not until 1824 that P.M.Roget made a scientific examination of what has come to be called persistence of vision: the eye is incapable of resolving motion below a threshold of about 1/20 second. In 1826, J.A.Paris, an English physician, introduced the thaumatrope, which had different images on each side of a disc; when spun, it gave the illusion of superimposition of the images. In 1833 a Belgian, Plateaux, constructed what he called the phenakistoscope (Figure 15.4); and an Austrian, Simon von Stampfer, independently invented a similar device called a stroboscope. A cardboard disc had a series of drawings around its periphery, each depicting a successive stage of an object in motion. The rotating images were viewed in a mirror through slots cut in the periphery, and gave the illusion of a moving image. A similar instrument which was based on putting the pictures inside a cylinder, the zoetrope (‘wheel of life’), was described by Horner in 1834, but did not come into widespread use until Desvignes popularized it in 1860. In 1877, Emile Reynaud patented his praxinoscope, whose images could be projected on to a screen; Reynaud also devised a system using paper strips to extend the number of drawings beyond the dozen possible around the periphery of a wheel or cylinder. The use of photographs instead of drawings, and even the provision of sequential stereo views was accomplished by William Thomas Shaw in 1861, using a viewing device which had a rotating shutter to keep the eye from seeing the transitions from image to image. The photographic recording and display of objects in motion was accomplished first by Edweard Muybridge, an English photographer who had emigrated to America. In 1872 he was hired by the ex-governor of California, Leland Stanford, to settle a bet that Stanford’s trotting horse Occident had all four feet off the ground at once when in a gallop. However, the wet-plate process was too slow to give incontrovertible proof, and it was not until 1878 that Muybridge was able to put together a system which settled the bet (in PART FOUR: COMMUNICATION AND CALCULATION 740 Stanford’s favour). Muybridge used twelve cameras with drop shutters, and specially treated wet plates permitting exposures of only 1/2000 second. In 1881, Muybridge met Etienne Jules Marey, a physiologist, and the painter Meissonier in France, where he showed some of his sequential photographic slides in motion by fastening them to a large disc; another counter-rotating disc with slots and an arc light, condenser and lens served to throw the images briefly on a screen. Muybridge claimed that he had first used this device, which he named a zoopraxiscope, in 1879 at Stanford’s house. This was the first motion picture projector. On his return to America in 1883, with encouragement from the painter Thomas Eakins, he greatly improved his recording technique at the University of Pennsylvania. He used batteries of twelve cameras with special high-speed lenses and shutters (which he patented as the electro expositor); after Figure 15.4: A disc for the 1833 phenakistoscope; two different, complete picture cycles are incorporated. INFORMATION 741 this, he designed a portable version. However, instead of pursuing the invention of what was destined to become a vast industry, his interest stayed with the recording and analysis of animal and human locomotion. The next important steps were made by Marey, who was interested in studying birds in flight. In 1882 he designed a portable multi-exposure camera in the form of a gun, with which he was able to take twelve exposures in a second, each of 1/720 second duration (Figure 15.5); a later device took ten exposures of 1/5000 second each. Taking this photographic gun to Naples, he ‘shot’ seagulls against the sky; the result was a series of silhouettes from which he modelled life-size images in wax which he viewed in a large zoetrope. In 1888 he used a roll of sensitive paper and built what could be considered the first motion picture camera, but this was limited to about forty exposures. Many other inventors were at work on motion picture devices before 1890, such as Donisthorpe (1876), Friese-Greene and his associates (1884 on) and Le Prince (1888). In 1892, William Dickson, a Scotsman working with Edison, built a camera which could take 46 pictures a second on Eastman celluloid film, and a corresponding viewing device, the kinetoscope. Edison credited the zoetrope and zoopraxiscope with giving him the idea, but claimed that the kinetoscope made significant improvements: pictures were taken from a single viewpoint; they were taken more rapidly, and the inter-image interval was reduced to below 1/7 second to give smooth motion; and (most important from the practical standpoint) celluloid film provided an image carrier of indefinite length. (Early kinetoscope films were in the form of an endless loop about 20m long (66ft), which was moved continuously past a viewing lens, transitions between images being hidden by a revolving shutter.) Edison Figure 15.5: Marey’s 1882 photographic revolver. . However, instead of pursuing the invention of what was destined to become a vast industry, his interest stayed with the recording and analysis of animal and human locomotion. The next important steps. musicians, Leopold Mannes and Leopold Godowsky, invented the first practical process based on the integral tripack; they sold it to the Eastman Kodak Company, which placed it on the market under the. strips to extend the number of drawings beyond the dozen possible around the periphery of a wheel or cylinder. The use of photographs instead of drawings, and even the provision of sequential stereo