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.