The Scientific American Boy; Or, The Camp at Willow Clump Island

out roads to the different important points. Our main highway ran from Point Lookout to Tiger's Tail. This ro

Bri

2. Frames for

The Spar

one frame was made 6 feet wide and the other 5 feet wide. The side and cross spars were mortised together and secured by lashing a rope around them. To make the frames more rigid we braced them with diagonal braces nailed on. When completed we set the frames up on opposite sides of the stream and with ropes carefully lowered their upper ends until they interlocked, the s

ope R

The Swi

d to a tree at each side about fifteen feet from the ground. A pulley block with a wheel or sheave 4 inches in diameter was mounted

ing 2-inch sheaves, and they, together with the large pulley or "traveling block," as we called it, cost us about $2.50. Two light ropes were fastened to the large traveling block, each rope long enough to reach across the stream. The ropes extended to opposite anchorages, where each was passed over a branch of the tree and belayed on a cleat within easy reach. A fellow could dra

The Rop

sion B

rrel-stave

cured from Lumberville half a dozen old barrels and used the staves as a flooring for the bridge. The staves were linked together

ground. A pair of parallel ropes were extended across the stream about three feet above the flooring, with which they were connected at intervals of five feet. The bridge w

on Br

t a pontoon bridge. We were fortunate in securing six good cider barrels at

nd they were placed on edge to prevent sagging. Of course we had no anchors for securing the barrels, but used instead large stones weighing about 100 pounds each, around which the anchor lines were fastened. We found it rather difficult to sink these improvised anchors at just the right places, for we were working at the very mouth of the mill-race, and were in constant danger of having our scow sucked down into the swirling channel. Once we were actuall

ng Rod

tumbling down a gorge in the hills and spread out into the Schreiners' ice pond. Thence it pursued its course very quietly through the low and somewhat swampy ground in the Schreiners' back yard. Over this brook Reddy was ver

m were so low that, instead of resting the floor of the bridge on top of the inclined frames, a

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 d

ing the

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

ng Rod

over Cedar

g Post

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 l

ig. 101. Two stout posts 7 feet long were connected at the top by a tie stick

ce was also nailed across the lower ends of the king posts. The frame thus formed was set up at the center of the span and temporarily held by nailing the lower tie piece to the wor

knife, we managed to make fairly good joints. A couple of long wire nails in each spar made the structure perfectly secure. The king posts were now sawed off just above the temporary tie piece, and the permanent cross beam was fastened to thes

t the shore ends. The floor beams were quite heavy and needed no support between the king posts and shore. A rustic floor was made of small logs sawed in two at Mr. Schreiner's sawmill. Light p