The Kaleidoscope.

Scientific American 40, 26.6.1847

This optical toy is formed by two plane mirrors, or slips of glass from 6 to 10 inches in length and from an inch to an inch and a half in breadth at one end, and a little narrower at the other, joined together along the edge lengthways and inclined to each other at an angle. The edges of the mirrors are kept in contact by a slip of black silk glued along the back of the plates, which must be coated with black varnish to prevent reflection. The glasses being adjusted at the prooer angle are placed within a tin tube, where they are kept in their proper position by pieces of cork or wood wedged in between them and the tube. One end of the tube has a small circular aperture in its centre to which the eye is applied. in the other end two plane glasses are fixed parallel to each other perpendicular to the axis of the tube, about an eighth of an inch apart. Between these glasses, which form a cell, the objects which produce the images are placed. These are generally fragments of colored glass, beads, &c., of such a size as easily move when the tube is turned round. On applying the eye to the aperture of the tube, the objhects within the cell at the other end are multiplied by repeated reflexion from the two mirrors and a succession of beautiful symmetrical images are presented to the vision. Every motion of the tube presents a succession of pleasing combinations.

This instrument was invented by Sir David Brewster, and it is said that 200,00 of them were sold in London and Paris in three months after it was made public.