The magic lantern is the ancestor of projection devices and particularly of the slide projector. Invented in the seventeenth century by Father Athanase Kircher in Germany and by Father De Châle in France, it allows images painted on glass plates to be projected through a lens, via the light of a candle or an oil lamp.
Initially christened the "lantern of fear" by its inventor, it was, after several successive names, renamed the "magic lantern" by the Jesuit Francesco Eschinardi because of the fascination that its images exert on the public.

Cochinchine - Cholon
Lanterne magique
Mottet 860 - @4163 #4890

Map shipped in 1906

Cochinchine - Cholon
Lanterne magique
Carte postée en 1906 Mottet 860 - @x4163 #4891

The magic lantern is made up of three elements: a light source, a painted glass plate and an objective (a converging lens). It works on the principle of the darkroom, where the light source (sun) and the projected images (landscapes) are replaced by artificial elements (lamp and painted glass plate). The light passes through the glass plate, then through the lens, to project the upside-down image (up-down) painted on the plate.

There are many variations: adding a concave mirror and other lenses to condense the light; light source of various kinds (candle, oil lamp, light bulb); Double-lens lantern allowing crossfade between two glass plates for two images. Glass plates are sometimes equipped with small mechanisms to partially animate the image.

Source : Wikipédia