Lantern slides were often used in nineteenth century Astronomy
courses. The slide projectors
often used oxy-hydrogen or oxy-acetylene light sources, sometimes directing
the flame toward a block of calcium chloride to produce a lime light.
Most of the slides had circular images 3" in diameter, held with a wire snap ring in a mahogany slider 4" by 7". Early images were entirely hand-painted, but later images probably used a photograph as the basis for the painting. All of the slides on this page are from the collection
of early physics teaching apparatus at Bowdoin College.
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