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photographic slides at their best, magic lantern lenses
needed improvement. Spherical aberration, which
blurred the edges of the projected image—more evident
with the fi ne detail of a photograph than with earlier
painted scenes—could be reduced when the Petzval
lens, designed for cameras in 1841, was adopted for
slide projection. Chromatic aberration, causing color
fringing—which became more apparent with mono-
chrome photographic images—was corrected with the
introduction of achromatic lenses.
In Britain in particular, from the 1850s, many magic
lanterns had wooden bodies, usually with a sheet metal
lining to protect the wood from the internal fl ame, with
a metal dome top and cowl. These wood-bodied projec-
tors, being cooler externally, were safer to operate. The
external metal parts were usually made from brass and
lacquered, the device taking on a prestigious appearance,
conferring status to the user.
From mid-century, professional users of the lantern—
lecturers and showmen—started to employ limelight as
an illuminant. Hydrogen and oxygen gases from leather
bags (later, metal cylinders), were mixed in the limelight
burner to produce a strong fl ame. This fl ame played on
a small cylinder of quicklime, which glowed white hot.
Much brighter than an oil lamp, limelight could produce
very large screen images.
Other illuminants introduced included, from the
1850s, the electric arc lamp—though providing the
necessary current was diffi cult and limited its use—and
from the 1890s, acetylene.
One important magic lantern, the Sciopticon, de-
veloped in the United States in 1869, had a larger
condenser than usual to avoid cropping the corners
of a projected image and an improved lamphouse for
cooler running.
From the 1830s, it became the practise for advanced
presentations to use two magic lanterns mounted side-
by-side, with a manually-operated rocking double-shut-
ter arrangement in front of the lenses. Each shutter had
a serrated edge, and as the shutter unit was operated
the image from one projector gradually faded out as
the image from its twin projector faded in, producing
a dissolve effect. These pairs were diffi cult for one
operator to manage, and in the late 1850s the vertical
double or biunial lantern was introduced and eventually
became popular. With one lantern above the other, ma-
nipulation of the slides was easier. From the 1870s the
triple lantern (some versions known as triunials) started
to appear from English, German, and later American
manufacturers. Some biunial and triunial lanterns had
slots in which glass fi lters could be placed, useful for
giving instant color tints to photographic slides.
A different method of construction became popular in
the United States. The base of the lantern comprised two
parallel metal rods, on which the components—refl ec-
tor, illuminant, condenser unit, slide stage and focusing
lens—were mounted. Each component could slide to
and fro, enabling very easy adjustment of their relative
positions. Vertically stacked double and triple versions
were also manufactured. In America slide projectors—
especially biunials—became known as stereopticons,
even though the image was not stereoscopic. (Today, the
term can lead to confusion as it is also used to mean a
hand-held or cabinet 3-D viewing device).
Most early slides were set in wooden frames, but from
the 1870s mechanical slide holders made the changing
of unframed glass slides easier.
Special lanterns for the projection of opaque pictures
and objects, including (from the 1840s) photographic
images, were known as episcopes, megascopes, or wun-
derkameras. Epidiascopes could also show transparent
slides.
The fi rst color photographs, made using the additive
process by James Clerk Maxwell in Britain in 1861,
were projected by means of superimposed slides from
three magic lanterns, each with a color fi lter: red, green,
and blue.
From the late eighteenth century, lanterns for domes-
tic use were made in Germany, which continued to be a
major producer throughout the nineteenth century, dur-
ing which production became widespread in England,
France, and the United States. Most lanterns for use
in the home had simple pressed steel bodies, and used
paraffi n (kerosene) lamps. The fi nish was sometimes
bare metal in the early days, and later a black ‘lacquer’
(paint), or a chemically-produced blue metallic effect.
From the 1840s to the 1920s, the miniature magic lan-
tern was a popular children’s toy. Slides were mostly
painted or lithographed, but some later German and
English toy lanterns showed photographic slides made
in small sizes.
Photographic societies frequently projected slide im-
ages made by their members, and this use of the lantern
for amateur photography extended its sphere of operation.
A specialist use was the projection of microphotographs,
by means of a high-power magnifying attachment. Some
lantern users, especially those with church and scientifi c
connections, were uncomfortable with the term ‘magic,’
referring instead to the ‘optical lantern.’
Photographic motion pictures came to the lantern
screen from 1895–96, and would eventually become a
special branch of optical projection. Many early fi lm
machines could also show conventional lantern slides,
usually by the operator simply pushing the lamphouse
from the cinematograph mechanism to the slide stage.
During the twentieth century, the magic lantern
evolved into the 35mm slide projector.
Stephen HerbertSee also: Lantern Slides.