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, through this channel, at the trigger end, and
a trigger made of heavy iron wire, bent to the shape shown in Fig. 51,
was hinged to the gun by a bolt which passed clear through the stock and
through both eyes of the trigger. By using two nuts on the bolt, and
tightening one against the other, they were prevented from working loose
and coming off. When we wanted to fire the gun the bowstring was drawn
back, and held by slipping it into the notch, and a nail was laid in the
channel with its head against the bowstring. Then, on pulling the
trigger, the bowstring was lifted out of the notch, and sent the nail
off sailing. The long-grooved barrel insured a very good aim.

MEGAPHONE.

[Illustration: Fig. 54. The Megaphone.]

[Illustration: Fig. 55. Layout of the Megaphone.]

[Illustration: Fig. 56. Brass Fastener.]

[Illustration: Fig. 57. The Mouthpiece.]

Another device we made in preparation for the expedition was a
megaphone. A sheet of light cardboard 30 inches square was procured. At
the center of one edge a pin was stuck into the cardboard, then a piece
of stout thread was looped over the pin and the two ends were knotted
together just 5 inches from the pin. Another knot was also made 29
inches from the pin. Now, with a pencil hooked into the loop, and
resting first against the inner knot and then against the outer one, two
arcs were drawn on the paper, one of 5-inch radius and the other of
29-inch radius. A line was now drawn from the pin to the point where the
longer arc met the right hand edge of the paper, and a dotted line was
drawn from the pin to a point 1-1/2 inches from the edge at the other
end of the arc. From a point 1 inch to the left of the pin we then drew
a line to the left end of the arc. With a scissors we cut the cardboard
along the arcs and straight lines, all but the dotted line, leaving a
piece of the shape shown in Fig. 55. This pie