area+photography

— aerial photography

— air photography

— analytical photography

— area photography

— daylight photography

— high-altitude photography

— high-speed photography

— infrared photography

— intelligence photography

— Interferometer photography

— low-altitude photography

— lunar photography

— medium-altitude photography

— metric photography

— night photography

— oblique aerial photography

— photography of instruments

— radarscope photography

— reconnaissance photography

— rocket-borne photography

— satellite photography

— schlieren photography

— stroboscopic photography

— technical photography

— ultrahigh-speed motion-picture photography

— ultraviolet photography

— vertical photography

— vertical-oblique aerial photography

— very-high-speed motion-picture photography

— air cartographic photography

— air photography

— area air photography

— bombardment photography

— camouflage detection photography

— close-look photography

— color air photography

— continuous strip photography

— day air photography

— dim-light photography

— EO intelligence photography

— fan-type air photography

— forward oblique air photography

— high-altitude route vertical photography

— intelligence holographic photography

— intelligence photography

— IR photography

— laser holographic air photography

— mapping photography

— multispectral photography

— night air photography

— oblique aerial photography

— overhead intelligence photography

— panoramic air photography

— radar photography

— reconnaissance photography

— slant-range photography

— space intelligence photography

— stereo radar photography

— strip air photography

— surveillance photography

— surveillance space photography

— terrain mapping air photography

— vertical photography

See also: INDEX BY SUBJECT AREA

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Abney, William de Wiveleslie

Acres, Birt

Anschütz, Ottomar

Archer, Frederick Scott

Baekeland, Leo Hendrik

Barnack, Oskar

Bayard, Hippolyte

Bennett, Charles Harper

Blanquart-Evrard, Louis-Désiré

Blumlein, Alan Dower

Brewster, Sir David

Carbutt, John

Carlson, Chester Floyd

Chevalier, Charles-Louis

Chrétien, Henri Jacques

Claudet, Antoine François Jean

Cros, Charles

Cros, Hortensius Emile Charles

Dagron, Prudent René-Patrice

Daguerre, Louis Jacques Mandé

Dallmeyer, John Henry

Dallmeyer, Thomas Rudolphus

Dallos, Joseph

Dancer, John Benjamin

De Forest, Lee

Demenÿ, Georges

Dickson, William Kennedy Laurie

Ding Huan

Ducos du Hauron, Arthur-Louis

Eastman, George

Edison, Thomas Alva

England, William

Fizeau, Armand Hippolyte Louis

Franklin, Benjamin

Gabor, Dennis

Galilei, Galileo

Gascoigne, William

Godowsky, Leopold Jr

Guinand, Pierre Louis

Hero of Alexandria

Herschel, John Frederick William

Hunt, Robert

Hurter, Ferdinand

Ives, Frederic Eugene

Jenkins, Charles Francis

Joly, John

Klic, Karol

Land, Edwin Herbert

Lauste, Eugène Augustin

Leeuwenhoek, Antoni van

Le Gray, Gustave

Lippershey, Hans

Lippman, Gabriel

Lumière, Auguste

Lumière, Charles Antoine

Maddox, Richard Leach

Maiman, Theodore Harold

Marey, Etienne-Jules

Marton, Ladislaus

Mees, Charles Edward Kenneth

Monckhoven, Désiré Charles Emanuel van

Muybridge, Eadweard

Neri, Antonio Ludovico

Niepce, Joseph Nicéphore

Niepce de St Victor, Claude Félix Abel

Paul, Robert William

Petzval, Josef Max

Poitevin, Alphonse Louise

Ponton, Mungo

Pouncy, John

Pretsch, Paul

Ravenscroft, George

Reichenbach, Georg Friedrich von

Röntgen, Wilhelm Conrad

Ross, Andrew

Schawlow, Arthur Leonard

Snellen, Hermann

Steinheil, Carl August von

Sutton, Thomas

Swan, Sir Joseph Wilson

Talbot, William Henry Fox

Taylor, William

Torricelli, Evangelista

Tournachon, Gaspard Félix

Voigtländer, Peter Wilhelm Friedrich

Waterhouse, Major-General James

Watkins, Alfred

Woodbury, Walter Bentley

Wratten, Frederick Charles Luther

Zeiss, Carl

See also: _about

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Aerospace

Agricultural and food technology

Architecture and building

Automotive engineering

Broadcasting

Canals

Chemical technology

Civil engineering

Domestic appliances and interiors

Electricity

Electronics and information technology

Horology

Land transport

Mechanical, pneumatic and hydraulic engineering

Medical technology

Metallurgy

Mining and extraction technology

Paper and printing

Photography, film and optics

Ports and shipping

Public utilities

Railways and locomotives

Recording

Steam and internal combustion engines

Synthetic materials

Telecommunications

Textiles

Weapons and armour

SUBJECT AREA: Photography, film and optics

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Auguste and his brother Louis Lumière (b. 5 October 1864 Besançon, France; d. 6 June 1948 Bandol, France) developed the photographic plate-making business founded by their father, Charles Antoine Lumière, at Lyons, extending production to roll-film manufacture in 1887. In the summer of 1894 their father brought to the factory a piece of Edison kinetoscope film, and said that they should produce films for the French owners of the new moving-picture machine. To do this, of course, a camera was needed; Louis was chiefly responsible for the design, which used an intermittent claw for driving the film, inspired by a sewing-machine mechanism. The machine was patented on 13 February 1895, and it was shown on 22 March 1895 at the Société d'Encouragement pour l'In-dustrie Nationale in Paris, with a projected film showing workers leaving the Lyons factory. Further demonstrations followed at the Sorbonne, and in Lyons during the Congrès des Sociétés de Photographie in June 1895. The Lumières filmed the delegates returning from an excursion, and showed the film to the Congrès the next day. To bring the Cinématographe, as it was called, to the public, the basement of the Grand Café in the Boulevard des Capuchines in Paris was rented, and on Saturday 28 December 1895 the first regular presentations of projected pictures to a paying public took place. The half-hour shows were an immediate success, and in a few months Lumière Cinématographes were seen throughout the world.

The other principal area of achievement by the Lumière brothers was colour photography. They took up Lippman's method of interference colour photography, developing special grainless emulsions, and early in 1893 demonstrated their results by lighting them with an arc lamp and projecting them on to a screen. In 1895 they patented a method of subtractive colour photography involving printing the colour separations on bichromated gelatine glue sheets, which were then dyed and assembled in register, on paper for prints or bound between glass for transparencies. Their most successful colour process was based upon the colour-mosaic principle. In 1904 they described a process in which microscopic grains of potato starch, dyed red, green and blue, were scattered on a freshly varnished glass plate. When dried the mosaic was coated with varnish and then with a panchromatic emulsion. The plate was exposed with the mosaic towards the lens, and after reversal processing a colour transparency was produced. The process was launched commercially in 1907 under the name Autochrome; it was the first fully practical single-plate colour process to reach the public, remaining on the market until the 1930s, when it was followed by a film version using the same principle.

Auguste and Louis received the Progress Medal of the Royal Photographic Society in 1909 for their work in colour photography. Auguste was also much involved in biological science and, having founded the Clinique Auguste Lumière, spent many of his later years working in the physiological laboratory.

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SUBJECT AREA: Photography, film and optics

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The son of a tax collector, Ducos du Hauron began researches into colour photography soon after the publication of Clerk Maxwell's experiment in 1861. In a communication sent in 1862 for presentation at the Académie des Sciences, but which was never read, he outlined a number of methods for photography of colours. Subsequently, in his book Les Couleurs en photographie, published in 1869, he outlined most of the principles of additive and subtractive colour photography that were later actually used. He covered additive processes, developed from Clerk Maxwell's demonstrations, and subtractive processes which could yield prints. At the time, the photographic materials available prevented the processes from being employed effectively. The design of his Chromoscope, in which transparent reflectors could be used to superimpose three additive images, was sound, however, and formed the basis of a number of later devices. He also proposed an additive system based on the use of a screen of fine red, yellow and blue lines, through which the photograph was taken and viewed. The lines blended additively when seen from a certain distance. Many years later, in 1907, Ducos du Hauron was to use this principle in an early commercial screen-plate process, Omnicolore. With his brother Alcide, he published a further work in 1878, Photographie des Couleurs, which described some more-practical subtractive processes. A few prints made at this time still survive and they are remarkably good for the period. In a French patent of 1895 he described yet another method for colour photography. His "polyfolium chromodialytique" involved a multiple-layer package of separate red-, green-and blue-sensitive materials and filters, which with a single exposure would analyse the scene in terms of the three primary colours. The individual layers would be separated for subsequent processing and printing. In a refined form, this is the principle behind modern colour films. In 1891 he patented and demonstrated the anaglyph method of stereoscopy, using superimposed red and green left and right eye images viewed through green and red filters. Ducos du Hauron's remarkable achievement was to propose theories of virtually all the basic methods of colour photography at a time when photographic materials were not adequate for the purpose of proving them correct. For his work on colour photography he was awarded the Progress Medal of the Royal Photographic Society in 1900, but despite his major contributions to colour photography he remained in poverty for much of his later life.

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SUBJECT AREA: Photography, film and optics

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The young Eastman was a clerk-bookkeeper in the Rochester Savings Bank when in 1877 he took up photography. Taking lessons in the wet-plate process, he became an enthusiastic amateur photographer. However, the cumbersome equipment and noxious chemicals used in the process proved an obstacle, as he said, "It seemed to be that one ought to be able to carry less than a pack-horse load." Then he came across an account of the new gelatine dry-plate process in the British Journal of Photography of March 1878. He experimented in coating glass plates with the new emulsions, and was soon so successful that he decided to go into commercial manufacture. He devised a machine to simplify the coating of the plates, and travelled to England in July 1879 to patent it. In April 1880 he prepared to begin manufacture in a rented building in Rochester, and contacted the leading American photographic supply house, E. \& H.T.Anthony, offering them an option as agents. A local whip manufacturer, Henry A.Strong, invested $1,000 in the enterprise and the Eastman Dry Plate Company was formed on 1 January 1881. Still working at the Savings Bank, he ran the business in his spare time, and demand grew for the quality product he was producing. The fledgling company survived a near disaster in 1882 when the quality of the emulsions dropped alarmingly. Eastman later discovered this was due to impurities in the gelatine used, and this led him to test all raw materials rigorously for quality. In 1884 the company became a corporation, the Eastman Dry Plate \& Film Company, and a new product was announced. Mindful of his desire to simplify photography, Eastman, with a camera maker, William H.Walker, designed a roll-holder in which the heavy glass plates were replaced by a roll of emulsion-coated paper. The holders were made in sizes suitable for most plate cameras. Eastman designed and patented a coating machine for the large-scale production of the paper film, bringing costs down dramatically, the roll-holders were acclaimed by photographers worldwide, and prizes and medals were awarded, but Eastman was still not satisfied. The next step was to incorporate the roll-holder in a smaller, hand-held camera. His first successful design was launched in June 1888: the Kodak camera. A small box camera, it held enough paper film for 100 circular exposures, and was bought ready-loaded. After the film had been exposed, the camera was returned to Eastman's factory, where the film was removed, processed and printed, and the camera reloaded. This developing and printing service was the most revolutionary part of his invention, since at that time photographers were expected to process their own photographs, which required access to a darkroom and appropriate chemicals. The Kodak camera put photography into the hands of the countless thousands who wanted photographs without complications. Eastman's marketing slogan neatly summed up the advantage: "You Press the Button, We Do the Rest." The Kodak camera was the last product in the design of which Eastman was personally involved. His company was growing rapidly, and he recruited the most talented scientists and technicians available. New products emerged regularly—notably the first commercially produced celluloid roll film for the Kodak cameras in July 1889; this material made possible the introduction of cinematography a few years later. Eastman's philosophy of simplifying photography and reducing its costs continued to influence products: for example, the introduction of the one dollar, or five shilling, Brownie camera in 1900, which put photography in the hands of almost everyone. Over the years the Eastman Kodak Company, as it now was, grew into a giant multinational corporation with manufacturing and marketing organizations throughout the world. Eastman continued to guide the company; he pursued an enlightened policy of employee welfare and profit sharing decades before this was common in industry. He made massive donations to many concerns, notably the Massachusetts Institute of Technology, and supported schemes for the education of black people, dental welfare, calendar reform, music and many other causes, he withdrew from the day-to-day control of the company in 1925, and at last had time for recreation. On 14 March 1932, suffering from a painful terminal cancer and after tidying up his affairs, he shot himself through the heart, leaving a note: "To my friends: My work is done. Why wait?" Although Eastman's technical innovations were made mostly at the beginning of his career, the organization which he founded and guided in its formative years was responsible for many of the major advances in photography over the years.

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SUBJECT AREA: Photography, film and optics

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A man of considerable intellect, Cros occupied himself with studies of topics as diverse as Sanskrit and the synthesis of precious stones. He was in particular interested in the possibility of colour photography, and deposited an account of his theories in a sealed envelope with the Académie des Sciences on 2 December 1867, with instructions that it should be opened in 1876. Learning of a forthcoming presentation on colour photography by Ducos du Hauron at the Société Française de Photographie, he arranged for the contents of his communication to be published on 25 February 1869 in Les Mondes. At the Société's meeting on 7 May 1869, Cros's letter was read and samples of colour photography from Ducos du Hauron were shown. Both had arrived at similar conclusions: that colour photography was possible with the analysis of colours using negatives exposed through red, green and blue filters, as demonstrated by Clerk Maxwell in 1861. These records could be reproduced by combining positive images produced in blue-green, magenta and yellow pigments or dyes. Cros and Ducos du Hauron had discovered the principle of subtractive colour photography, which is used in the late twentieth century. In 1878 Cros designed the Chromometre, a device for measuring colours by mixing red, green and blue light, and described the device in a paper to the Société Française de Photographie on 10 January 1879. With suitable modification, the device could be used as a viewer for colour photographs, combining red, green and blue positives. In 1880 he patented the principle of imbibition printing, in which dye taken up by a gelatine relief image could be transferred to another support. This principle, which he called hydrotypie, readily made possible the production of three-colour subtractive photographic prints.

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SUBJECT AREA: Photography, film and optics, Telecommunications

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Steinheil studied under Gauss at Göttingen and Bessel at Königsberg before jointing his parents at Munich. There he concentrated on optics before being appointed Professor of Physics and Mathematics at the University of Munich in 1832. Immediately after the announcement of the first practicable photographic processes in 1839, he began experiments on photography in association with another professor at the University, Franz von Kobell. Steinheil is reputed to have made the first daguerreotypes in Germany; he certainly constructed several cameras of original design and suggested minor improvements to the daguerreotype process. In 1849 he was employed by the Austrian Government as Head of the Department of Telegraphy in the Ministry of Commerce. Electromagnetic telegraphy was an area in which Steinheil had worked for several years previously, and he was now appointed to supervise the installation of a working telegraphic system for the Austrian monarchy. He is considered to be the founder of electromagnetic telegraphy in Austria and went on to perform a similar role in Switzerland.

Steinheil's son, Hugo Adolph, was educated in Munich and Augsburg but moved to Austria to be with his parents in 1850. Adolph completed his studies in Vienna and was appointed to the Telegraph Department, headed by his father, in 1851. Adolph returned to Munich in 1852, however, to concentrate on the study of optics. In 1855 the father and son established the optical workshop which was later to become the distinguished lens-manufacturing company C.A. Steinheil Söhne. At first the business confined itself almost entirely to astronomical optics, but in 1865 the two men took out a joint patent for a wide-angle photographic lens claimed to be free of distortion. The lens, called the "periscopic", was not in fact free from flare and not achromatic, although it enjoyed some reputation at the time. Much more important was the achromatic development of this lens that was introduced in 1866 and called the "Aplanet"; almost simultaneously a similar lens, the "Rapid Rentilinear", was introduced by Dallmeyer in England, and for many years lenses of this type were fitted as the standard objective on most photographic cameras. During 1866 the elder Steinheil relinquished his interest in lens manufacturing, and control of the business passed to Adolph, with administrative and financial affairs being looked after by another son, Edward. After Carl Steinheil's death Adolph continued to design and market a series of high-quality photographic lenses until his own death.

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SUBJECT AREA: Photography, film and optics

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Educated at Harrow, where he first showed an interest in science, and at Cambridge, Talbot was an outstanding scholar and a formidable mathematician. He published over fifty scientific papers and took out twelve English patents. His interests outside the field of science were also wide and included Assyriology, etymology and the classics. He was briefly a Member of Parliament, but did not pursue a parliamentary career.

Talbot's invention of photography arose out of his frustrating attempts to produce acceptable pencil sketches using popular artist's aids, the camera discura and camera lucida. From his experiments with the former he conceived the idea of placing on the screen a paper coated with silver salts so that the image would be captured chemically. During the spring of 1834 he made outline images of subjects such as leaves and flowers by placing them on sheets of sensitized paper and exposing them to sunlight. No camera was involved and the first images produced using an optical system were made with a solar microscope. It was only when he had devised a more sensitive paper that Talbot was able to make camera pictures; the earliest surviving camera negative dates from August 1835. From the beginning, Talbot noticed that the lights and shades of his images were reversed. During 1834 or 1835 he discovered that by placing this reversed image on another sheet of sensitized paper and again exposing it to sunlight, a picture was produced with lights and shades in the correct disposition. Talbot had discovered the basis of modern photography, the photographic negative, from which could be produced an unlimited number of positives. He did little further work until the announcement of Daguerre's process in 1839 prompted him to publish an account of his negative-positive process. Aware that his photogenic drawing process had many imperfections, Talbot plunged into further experiments and in September 1840, using a mixture incorporating a solution of gallic acid, discovered an invisible latent image that could be made visible by development. This improved calotype process dramatically shortened exposure times and allowed Talbot to take portraits. In 1841 he patented the process, an exercise that was later to cause controversy, and between 1844 and 1846 produced The Pencil of Nature, the world's first commercial photographically illustrated book.

Concerned that some of his photographs were prone to fading, Talbot later began experiments to combine photography with printing and engraving. Using bichromated gelatine, he devised the first practicable method of photo engraving, which was patented as Photoglyphic engraving in October 1852. He later went on to use screens of gauze, muslin and finely powdered gum to break up the image into lines and dots, thus anticipating modern photomechanical processes.

Talbot was described by contemporaries as the "Father of Photography" primarily in recognition of his discovery of the negative-positive process, but he also produced the first photomicrographs, took the first high-speed photographs with the aid of a spark from a Leyden jar, and is credited with proposing infra-red photography. He was a shy man and his misguided attempts to enforce his calotype patent made him many enemies. It was perhaps for this reason that he never received the formal recognition from the British nation that his family felt he deserved.

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SUBJECT AREA: Photography, film and optics

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Ives trained as a printer in Ithaca, New York, and became official photographer at Cornell University at the age of 18. His research into photomechanical processes led in 1886 to methods of making halftone reproduction of photographs using crossline screens. In 1881 he was the first to make a three-colour print from relief halftone blocks. He made significant contributions to the early development of colour photography, and from 1888 he published and marketed a number of systems for the production of additive colour photographs. He designed a beam-splitting camera in which a single lens exposed three negatives through red, green and blue filters. Black and white transparencies from these negatives were viewed in a device fitted with internal reflectors and filters, which combined the three colour separations into one full-colour image. This device was marketed in 1895 under the name Kromskop; sets of Kromograms were available commercially, and special cameras, or adaptors for conventional cameras, were available for photographers who wished to take their own colour pictures. A Lantern Kromskop was available for the projection of Kromskop pictures. Ives's system enjoyed a few years of commercial success before simpler methods of making colour photographs rendered it obsolete. Ives continued research into colour photography; his later achievements included the design, in 1915, of the Hicro process, in which a simple camera produced sets of separation negatives that could be printed as dyed transparencies in complementary colours and assembled in register on paper to produce colour prints. Later, in 1932, he introduced Polychrome, a simpler, two-colour process in which a bipack of two thin negative plates or films could be exposed in conventional cameras. Ives's interest extended into other fields, notably stereoscopy. He developed a successful parallax stereogram process in 1903, in which a three-dimensional image could be seen directly, without the use of viewing devices. In his lifetime he received many honours, and was a recipient of the Royal Photographic Society's Progress Medal in 1903 for his work in colour photography.

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SUBJECT AREA: Photography, film and optics

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In 1841, while studying at Cambridge, Sutton became interested in photography and tried out the current processes, daguerreotype, calotype and cyanotype among them. He subsequently settled in Jersey, where he continued his photographic studies. In 1855 he opened a photographic printing works in Jersey, in partnership with L.-D. Blanquart- Evrard, exploiting the latter's process for producing developed positive prints. He started and edited one of the first photographic periodicals, Photographic Notes, in 1856; until its cessation in 1867, his journal presented a fresher view of the world of photography than that given by its London-based rivals. He also drew up the first dictionary of photography in 1858.

In 1859 Sutton designed and patented a wideangle lens in which the space between two meniscus lenses, forming parts of a sphere and sealed in a metal rim, was filled with water; the lens so formed could cover an angle of up to 120 degrees at an aperture of f12. Sutton's design was inspired by observing the images produced by the water-filled sphere of a "snowstorm" souvenir brought home from Paris! Sutton commissioned the London camera-maker Frederick Cox to make the Panoramic camera, demonstrating the first model in January 1860; it took panoramic pictures on curved glass plates 152×381 mm in size. Cox later advertised other models in a total of four sizes. In January 1861 Sutton handed over manufacture to Andrew Ross's son Thomas Ross, who produced much-improved lenses and also cameras in three sizes. Sutton then developed the first single-lens reflex camera design, patenting it on 20 August 1961: a pivoted mirror, placed at 45 degrees inside the camera, reflected the image from the lens onto a ground glass-screen set in the top of the camera for framing and focusing. When ready, the mirror was swung up out of the way to allow light to reach the plate at the back of the camera. The design was manufactured for a few years by Thomas Ross and J.H. Dallmeyer.

In 1861 James Clerk Maxwell asked Sutton to prepare a series of photographs for use in his lecture "On the theory of three primary colours", to be presented at the Royal Institution in London on 17 May 1861. Maxwell required three photographs to be taken through red, green and blue filters, which were to be printed as lantern slides and projected in superimposition through three projectors. If his theory was correct, a colour reproduction of the original subject would be produced. Sutton used liquid filters: ammoniacal copper sulphate for blue, copper chloride for the green and iron sulphocyanide for the red. A fourth exposure was made through lemon-yellow glass, but was not used in the final demonstration. A tartan ribbon in a bow was used as the subject; the wet-collodion process in current use required six seconds for the blue exposure, about twice what would have been needed without the filter. After twelve minutes no trace of image was produced through the green filter, which had to be diluted to a pale green: a twelve-minute exposure then produced a serviceable negative. Eight minutes was enough to record an image through the red filter, although since the process was sensitive only to blue light, nothing at all should have been recorded. In 1961, R.M.Evans of the Kodak Research Laboratory showed that the red liquid transmitted ultraviolet radiation, and by an extraordinary coincidence many natural red dye-stuffs reflect ultraviolet. Thus the red separation was made on the basis of non-visible radiation rather than red, but the net result was correct and the projected images did give an identifiable reproduction of the original. Sutton's photographs enabled Maxwell to establish the validity of his theory and to provide the basis upon which all subsequent methods of colour photography have been founded.

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SUBJECT AREA: Photography, film and optics

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Abney began his career as an officer in the Army and was an instructor in chemistry in the Royal Engineers at Chatham, where he made substantial use of photography as a working tool. He retired from the Army in 1877 and joined the Science and Art Department at South Kensington. It was at Abney's suggestion that a collection of photographic equipment and processes was established in the South Kensington Museum (later to become the Science Museum Photography Collection).

Abney undertook significant researches into the nature of gelatine silver halide emulsions at a time when they were being widely adopted by photographers. Perhaps his most important practical innovations were the introduction of hydroquinone as a developing agent in 1880 and silver gelatine citrochloride emulsions for printing-out paper (POP) in 1882. However, Abney was at the forefront of many aspects of photographic research during a period of great innovation and change in photography. He devised new techniques of photomechanical printing and conducted significant researches in the fields of photochemistry and spectral analysis. Abney published throughout his career for both the specialist scientist and the more general photographic practitioner.

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SUBJECT AREA: Photography, film and optics

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Apprenticed to a silversmith in London, Archer's interest in coin design and sculpture led to his taking up photography in 1847. Archer began experiments to improve Talbot's calotype process and by 1848 he was investigating the properties of a newly discovered material, collodion, a solution of gun-cotton in ether. In 1851 Archer published details of a process using collodion on glass plates as a carrier for silver salts. The process combined the virtues of both the calotype and the daguerreotype processes, then widely practised, and soon displaced them from favour. Collodion plates were only sensitive when moist and it was therefore essential to use them immediately after they had been prepared. Popularly known as "wet plate" photography, it became the dominant photographic process for thirty years.

Archer introduced other minor photographic innovations and in 1855 patented a collodion stripping film. He had not patented the wet-plate process, however, and made no financial gain from his photographic work. He died in poverty in 1857, a matter of some embarrassment to his contemporaries. A subscription fund was raised, to which the Government was subsequently persuaded to add an annual pension.

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SUBJECT AREA: Photography, film and optics

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The only son of Sir William Herschel, the famous astronomer, John graduated from Cambridge in 1813 and went on to become a distinguished astronomer, mathematician and chemist. He left England in November 1833 to set up an observatory near Cape Town, South Africa, where he embarked on a study of the heavens in the southern hemisphere. He returned to England in the spring of 1838, and between 1850 and 1855 Herschel served as Master of the Royal Mint. He made several notable contributions to photography, perhaps the most important being his discovery in 1819 that hyposulphites (thiosulphates) would dissolve silver salts. He brought this property to the attention of W.H.F. Talbot, who in 1839 was using a common salt solution as a fixing agent for his early photographs. After trials, Talbot adopted "hypo", which was a far more effective fixative. It was soon adopted by other photographers and eventually became the standard photographic fixative, as it still is in the 1990s. After hearing of the first photographic process in January 1839, Herschel devised his own process within a week. In September 1839 he made the first photograph on glass. He is credited with introducing the words "positive", "negative" and "snapshot" to photography, and in 1842 he invented the cyanotype or "blueprint" process. This process was later to be widely adopted by engineers and architects for the reproduction of plans and technical drawings, a practice abandoned only in the late twentieth century.

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