“Two or more glass discs mounted in a solid wood frame. The glasses are set in recessed holes and held in place by wire retaining springs. No cover glass is provided as the glasses are seated below the surface of the frame to provide protection for the painting.

Similar to slides illustrated by Kircher in 1671.

First commercially produced by Philip Carpenter in about 1821, with the subjects printed in outline from copper plates and then hand-painted. The frames are often marked with a die-stamped impression 'Copper Plate Slider' or the words sometimes appear on a printed label.

Seldom produced after about 1850. Superseded by the Single Slide.”