Fig. 315. K Frame (make one).
We built the complete set of frames before attempting to erect the bridge. Then we began by building the towers. Two A frames were set on end and spaced 4 feet apart at the top and 5 feet apart at the bottom, measuring not from the inner but from the outer edges of the frames. In this position they were connected by short spars, notched in place.
Fig. 316. L Frame (make two). The notches for these connecting spars will be seen in Fig. 305 on the main or vertical timbers of frame A, just below the upper and middle cross sticks and above the lower cross sticks. The upper connecting spars were wedged tightly under the cross sticks, and served as an additional support for them. Diagonal braces were nailed from one frame to the other, as illustrated in Fig. 318. The towers were built
Fig. 317. Notching the Sticks Together. on opposite banks, at the mouth of the lagoon, and when completed we lowered them carefully down the banks into the water. According to directions they were to be set just 30 feet apart, measuring from the center of one tower to the center of the other. The water was quite shallow where the towers rested, but the bottom was pretty firm. Holes were dug in the bottom for the legs of the tower to set into, and then large stones were piled around each leg to provide a firm foundation for the towers.
Setting Up the Frames.
