At last we found one that seemed
properly suited to the requirements. It was called a "king post truss,"
and was very similar to the king rod bridge. While the design of the
bridge was simple, yet it required some ingenuity to put it together. In
setting up the other bridge the scow had been anchored in the center of
the stream and used as a working platform, from which it had been an easy
matter to put the various parts together. In this case our scow was
obviously of no use, so we laid a couple of long logs across the chasm,
and a few slats were nailed across them to provide a temporary bridge or
working platform. The platform sagged considerably at the center, because
the span was fully eighteen feet; but the logs were large, and we knew
they were strong enough to support our weight. However, as an extra
precaution, we tied the ends to stakes driven in the ground, so that they
could not possibly slip off the banks.
[Illustration: Fig. 101. The King Post Frame.]
[Illustration: Fig. 102. The King Posts Set in Position.]
[Illustration: Fig. 103. The Permanent Cross Beam Made Fast.]
First we set about constructing the king posts, which were made as shown
in Fig. 101. Two stout posts 7 feet long were connected at the top by a
tie stick, which spaced them 4 feet apart.
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