(Fig. 4)
The Parts in Detail for Making the Tripods... (Fig. 5, Fig. 6)
The tripod head is formed of a wood disk, 5 in. in diameter, with a hole in the center, and three small blocks of wood, 1 in. square and 2 in. long, nailed to the under side, as shown in Fig. 5. The tripod legs are made of light strips of wood, 3/8 in. thick, 1 in. wide and 5 ft. long. Two of these strips, nailed securely together to within 20 in. of the top, constitute one leg. The upper unnailed ends are spread to slip over the blocks on the tripod top. These ends are bored to loosely fit over the headless nails driven part way into the block ends. One tripod leg is shown in Fig. 6.
...and the Shutter for Flashing the Light,... (Fig. 7, Fig. 8)
The screen, or shutter, is mounted on a separate tripod and is shown in Fig. 7. Cut out two slats, 3/8 in. thick, 2-1/2 in. wide and 6 in. long, from hard wood, and taper both edges of these slats down to 3/16 in. Small nails are driven into the ends of the slats and the heads are filed off so that the projecting ends will form trunnions for the slats to turn on. Make a frame of wood pieces, 3/4 in. thick and 2-1/2 in. wide, the opening in the frame being 6 in. square. Before nailing the frame together bore holes in the side uprights for the trunnions of the slats to turn in. These holes are 1-3/4 in. apart. The frame is then nailed together and also nailed to the tripod top. The shutter is operated with a key very similar to a telegraph key. The construction of this key is shown in Fig. 7. A part of a spool is fastened to a stick that is pivoted on the opposite side of the frame. The key is connected to the slats in the frame with a bar and rod, to which a coil spring is attached, as shown in Fig. 8. Figure 9 shows the positions of the tripods when the instrument is set to flash the sunlight through the shutter. The regular telegraph code is used in flashing the light.
...and Diagram Showing the Location of the Tripods to Direct the Light through the Shutter (Fig. 9)