Fig. 2.
Fig. 3.
Now for the construction. Get some thin board—deal is very good for the purpose; it is to be a quarter of an inch thick—cut two pieces out of it for the top and bottom, the shape shown in [Fig. 1].
Fig. 4.
The dimensions of these pieces are as follows. The sides B and E four and a half inches long; the side A five and a quarter inches long; the other two sides are each to be three and three-quarter inches long. The angles where A joins B and E are each to be a right angle; so is the angle where C joins D. The two other angles are to be a hundred and thirty-five degrees each, as marked in [Fig. 1]. The sides of the box are to be eight inches long each, and are a little less in width than the edges of the top and bottom that correspond, so that when put together the outside of the box is flush with the top and bottom. The joints are to be glued together, and can be strengthened with pins driven in like small nails. The side E is not to be covered in all the way up, but only about two inches and a half from the bottom; but this depends upon the height that the nozzle of the lantern comes up this side when placed against it. [Fig. 2] shows the opening left. When the glue is quite dry unscrew the brass focussing-tube from the lantern and place the box with the side C resting against the nozzle of the lantern, and mark round the nozzle on the side. Find the centre of this circle, and through it draw a line right across the side C, parallel to the top and bottom, and continue this line across the side B in the same way, as seen in [Fig. 3]. Find the centre of these two lines, and with these two centres mark a circle on each of these two sides, the one in the side B to be of a size to fit the brass focussing-tube, and the one in the side C to be about three inches in diameter, or large enough to allow the nozzle of the lantern to fit into it as far as it will go without coming between the picture and the lens, as seen in [Fig. 4].
Fig. 5.
The remaining part to be made is the shutter to carry the photographs. This must be exactly the same size as the opening left in the side E, and is to be made out of the same quarter inch board. Let it be quite square at the sides and corners. The opening in the side E is to be equal in length to twice the distance of the centres of the holes in the sides B and C from the top edge of the sides where they join the top board. On each side of the shutter, in each corner, fasten a clip, as in [Fig. 5]. These clips can be made out of card or thin metal, cut in the shape shown, and fastened to the shutter with small screws or short pins. Mark the middle of the top and bottom edges of the shutter and place it in its place in the side E, and mark on the side the points where these marks come to. Take the shutter out again and bore a hole in the bottom edge of it about half an inch deep, and large enough for a stout pin to go into. In the lower part of the side E, and in the edge that the shutter will rest on, drive a stout pin in middle so as to form a pivot for the shutter, leaving out about a quarter of an inch, and cut off the head. Replace the shutter, fitting the pin into the hole bored for it, and drive a pin through the top board right into it, so as to form a second pivot. The shutter will revolve round these two pivots and expose the sides alternately to the lens. Fix two clips to the edge of the top board to keep the shutter in place while shut. Cover the whole of the box with unglazed black paper.