A magic lantern show. The lanterns used differ little from Kircher's in the 17th century, consisting of box with lamp placed at focus of concave mirror. Reflected light falls on condensing lens which concentrates it on a slide. Here two lanterns are being used to give dissolving views. The apparatus is mounted on a wheeled trolley, so that the operator behind the screen can alter the size of the image seen by the audience. From A Ganot Natural Philosophy, London, 1887.