Heads may be made to nod, faces to laugh; eyes may be made to roll, teeth to gnash; crocodiles may be made to swallow tigers; combats may be represented; but one of the most instructive uses of the slides is to make them illustrative of astronomy, and to show the rotation of the seasons, the cause of eclipses, the mountains in the moon, spots on the sun, and the various motions of the planetary bodies, and their satellites.
THE PHANTASMAGORIA.
Between the phantasmagoria and the magic lantern there is this difference: in common magic lanterns the figures are painted on transparent glass, consequently the image on the screen is a circle of light having figures upon it; but in the phantasmagoria all the glass is made opaque, except the figures, which, being painted in transparent colours, the light shines through them, and no light can come upon the screen except that which passes through the figure, as is [here] represented.
There is no sheet to receive the picture, but the representation is thrown on a thin screen of silk or muslin placed between the spectators and the lantern. The images are made to appear approaching and receding by removing it further from the screen, or bringing it nearer to it. This is a great advantage over the ordinary arrangements of the magic lantern, and by it the most astonishing effects are often produced.
DISSOLVING VIEWS.
The dissolving views, by which one landscape or scene appears to pass into the other while the scene is changing, are produced by using two magic lanterns placed side by side, and that can be a little inclined towards each other when necessary, so as to mix together the rays of light proceeding from the lenses of each, which produces that confusion of images, in which one view melts as it were into the other, which gradually becomes clear and distinct; the principle being the gradual extinction of one picture, and the production of another.