f the inclined frames, as we had done over the
mill-race, it was suspended from the spars by means of wires. The
crossing ends of the spars were nailed together and their lower ends
were firmly planted about four feet apart in the banks of the brook. A
stick nailed to the apex of each pair of spars served temporarily to
brace them apart. The center cross beam of the bridge was now suspended
from the spars by means of heavy galvanized iron wire (No. 14, I should
say). The beam was hung high enough to allow for stretch of the wire,
making the roadway incline upward from both sides to the center. Aside
from carrying the floor of the bridge, this beam was used to brace the
inclined spars when the temporary crosspiece was removed. The ends of
the beam projected about thirty inches beyond the bridge at each side,
and they supported braces which extended diagonally upward to the
crossing ends of the spars. When this was done the temporary crosspiece
above referred to was removed. As the span between the center cross beam
and the banks was a little too long to provide a steady floor, a couple
of intermediate cross beams were suspended from the inclined spars. The
floor beams were then laid in place and covered with a flooring of
slabs.

STIFFENING THE BRIDGE.

The bridge was a pretty good one, except for a slight unsteadiness
between the center and either end. When Uncle Ed saw it he showed us at
once where the trouble lay. Our intermediate cross beams were hung from
the center of the spars, and consequently made them bend, because the
strain came across their length, while at the center of the bridge there
was no chance for the spars to bend, because the strain was exerted
along their length, that is, it tended merely to push the ends of the
spars deeper into the banks. To remedy the trouble he proposed propping
up the center of each spar with a brace running from the center
crosspiece. The dotted lines in Fig. 100 show how these braces were
applied. They made the floor perfectly solid throughout, and gave the
bridge a much better appearance. Uncle Ed told us that the structure
might be called a "king rod truss," except that in place of rods we had
used wires.

[Illustration: The King Rod Bridge.]

[Illustration: The Bridge over Cedar Brook Gorge.]

THE KING POST BRIDGE.

The other bridge on the Schreiner property was built in the following
summer, just before we started on our second expedition to Willow Clump
Isl