Monarch Ethopticon magic lantern, c 1880.

This double lens magic lantern was manufactured by the Riley Brothers of Bradford, Yorkshire. It projected 3.25 inches x 3.25 inches magic lantern slides. Effectively two slide projectors on top of one another, it could be used to present sophisticated magic lantern shows. Images could be superimposed on each other, and views could be transformed from day to night by means of opening one lens and closing another.