An Encyclopedia of the History of Technology part 76 doc

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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
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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
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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
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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,
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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-
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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.
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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.
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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
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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.
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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.