some
heavy copper wire. With the aid of the mystified Jerry he tore two
stout boards up from the floor of the tractor.

"Now we've got to work rapidly, fellows," he said, "for it will soon be
dark, and we don't want to attract attention to ourselves by making a
light.

"Here is what I am going to try to do: That wire is strung really from
mountain to mountain, running down a slight grade from where it is
fastened here to where it is tied up over there. I don't know how strong
it is, or how securely it is fastened at the other end, but I'm going to
find out.

"You've all seen those trolley-like boxes that run on wires in
department stores, with which the clerk sends your money to the
cashier's desk, and the cashier returns the change? Well, I'm going to
construct something on the same principle, only I want to make it strong
enough to carry my weight.

"If I can do that, and the wire holds, the incline is sufficient to
carry a passenger to the other mountain without any propelling power.
I'll try it first, and carry with me one end of this reel of copper
wire. If I get over all right I'll attach the wire to the little oar and
you fellows can haul it back for the next passenger, and so on until all
of us are over."

Slim looked dubious. "How thick is that wire?" he demanded anxiously.

"You know Slim's a trifle heavy," Jerry reminded the lieutenant.

"Well," said Slim in a serious tone, "I'd rather fall into the hands of
the Germans, and have some chance for my life, than spatter myself all
over the bottom of that ravine."

While this conversation was going on, Lieutenant Mackinson was boring a
hole about two inches in from each of the four comers of one of the
planks taken from the floor of the truck.

"This ought to do for a seat," he said, as he began running pieces of
the heavy copper wire, of equal length, through each of the holes.

He then laid this part of the work aside for a moment and began filing
off one end of the riveted axle that held the pulley wheel in its frame.
When he had knocked this axle out he tried one of the bolts and found
that it fitted almost exactly, and that the wheel ran freely upon it.

"Have to have that wheel off to put the thing on the telegraph wire," he
explained, as he began securely fastening the copper wires into the
bottom of the pulley frame.

Completed, the thing looked for all the world like a miniature trapeze
seat.

"Now," he said, slipping a wrench into his p