ers. The reason for this, as Uncle Ed explained it, was because
the thickness of our sticks would vary considerably, and it was
important that many of the measurements be exact, otherwise the
frames would not fit into each other as they should. Another
thing to which he called our attention was the fact that frames
_A_, _B_, _E_, _F_, _H_, _K_ and _L_ were stiffened with cross
braces, while the rest were not. The braced frames, he wrote, were those
which would be under a compression strain, while the others would be
under tension; that is, when any weight was placed on the bridge it
would push against the ends of the braced frames, trying to crush them,
but would pull on the unbraced frames, trying to tear them apart. In
fact, the bridge would have been just as strong had we used heavy iron
wire in place of the unbraced frames, and the only reason Uncle Ed did
not recommend our doing so was because we had no simple way of
stretching the wire taut.

[Illustration: Fig. 309. E Frame (make four).]

[Illustration: Fig. 310. F Frame (make two).]

[Illustration: Fig. 311. G Frame (make two).]

[Illustration: Fig. 312. H Frame (make one).]

[Illustration: Fig. 313. I Frame (make one).]

[Illustration: Fig. 314. J Frame (make one).]

[Illustration: Fishing off the Cantilever Bridge.]

[Illustration: The Cantilever Bridge in Reddy's Back Yard.]

ERECTING THE TOWERS.

[Illustration: Fig. 315. K Frame (make one).]

[Illustration: Fig. 316. L Frame (make two).]

[Illustration: Fig. 317. Notching the Sticks Together.]

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. 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 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 th