The materials needed for its construction will be some sheet Russia iron, thin mahogany or cherry boards three-eighths of an inch in thickness and six inches wide, some round-headed brass screws, small hinges, a camera-bellows, and the necessary lenses and lamp. The tools include a light pair of metal shears, a fine-tooth saw and a compass-saw, a small hammer, plane, and screw-driver, and a light cold-chisel.
To begin with, obtain a board twenty inches long, six inches wide, and three-eighths of an inch in thickness to serve as the base-board. Treat this board to several successive thin coats of shellac, and rub down the last coat with fine sand-paper to give it a smooth surface. Cut another piece six inches wide, eight and one-eighth inches long, and in it make a round hole about four and a half inches in diameter, through which the case that contains the condenser-lenses may pass and fit snugly. This board is to be placed nine inches from one end of the base-board, and fastened to it in a standing position with long, slim screws driven into the lower end through the underside of the base-board. Fig. 11 shows the arrangement of these boards, also the runners and sheet-iron hood.
From a sheet of Russia iron cut a piece nine and a half inches wide and twenty-three inches long, and have a tinsmith roll one edge over a piece of wire so as to stiffen it. With a rule and piece of chalk divide and mark off the sheet into three divisions, the end ones measuring eight and a half by nine inches and the middle one six by nine inches.
CONSTRUCTION OF THE STEREOPTICON
Fig. 11. Fig. 12. Fig. 13. Fig. 14 A. Fig. 14 B.
Lay the sheet on a board at the edge of a table so that a chalked line is directly over the sharp edge, and, holding it down firmly with one hand, bend the iron down with the other, forming a right angle. Bend the iron on the remaining line in a similar manner, and the hood is formed.
In the top of this hood, at the middle, mark off an oblong two inches wide and six inches long; then cut out the piece of iron with a cold-chisel and a hammer, laying the sheet-iron on the upturned surface of an old flat-iron. File or emery-paper the edges of the opening to render them smooth, then cut an opening in one side, three and a half inches high by four inches long, for a door.