Crossbow.

Reddy had a shotgun which he wanted to bring along, but my father, and
Dutchy's as well, wouldn't let us go camping if there was to be any
gunpowder along, so we had to leave it behind. Of course we didn't miss it
at all when we got to the island, because there was so much else to do;
but we all agreed with Dutchy, that "it wouldn't be no sort of a
scientific expedition without takin' a gun along." As a substitute I
suggested a bow and arrow. They all laughed at such a "kiddish" idea; all
but Bill, I mean.

"It ain't such a bad notion," said he, "only a crossbow would be better.
I've seen them made out of umbrella ribs so they'd shoot like greased
lightning." Of course we had to have one of these wonderful weapons. Down
in the ash heap we found two broken umbrellas with 27-inch ribs. Bill
selected ten good ribs, from which he wrenched off the spreaders with a
pair of pliers. The ribs were then bound together by winding stout twine
around them. The winding was very evenly and closely done, so that the
cord completely covered the ribs, making a solid rod of spring steel. But
before winding we had laid in between the ribs a piece of heavy twine, to
which the bowstrings could be tied after the bow was all wound. The stock
of our crossbow was cut out of a board of soft wood 1 inch thick to as
near the shape of a gun as we could get it. A hole was drilled through the
muzzle end to receive the bow, and then the bowstring was tied fast. Along
the upper edge of the barrel a V-shaped channel was cut. The channel was
not very deep, only enough to receive a tenpenny nail with the head
projecting half-way above the sides. A notch was cut across the barrel,