in what you call 'Physics.'"

"Speak out," laughed Colonel Howell. "We've utilized all our own ideas;
that is, all but one, and I don't like that. I suppose we can dig a pit
around the pipe and smother the blaze. But that's goin' to be quite a
job, and I'm not sure it would work."

"A pit!" exclaimed Paul. "Now I've got it. They used to tell me, when you
strike a force you can't handle, try to break it up into parts."

Colonel Howell looked up quickly.

"We don't need a pit," went on Paul, "but something like a trench. Let's
dig down alongside the pipe until we're ten or fifteen feet beneath the
ground and then tap the tube and let some of the gas out where it won't
do any harm. If we can't drill a hole, we can rig up a long-handled
chisel and punch an opening. When the gas rushes out, down there in the
trench, maybe it won't catch fire for a few minutes and it's sure to shut
off a good deal of the pressure at the mouth of the tube. If it does,
maybe we can get the cap and the regulator on the top. Then we can plug
the opening below. It'll leak, of course, but the regulator'll fix things
so we can use the gas at least."

Colonel Howell thought a moment and then slapped the young man on the
back. Without a word, he hurried to the two workmen and in a few moments
Ewen and Miller had begun digging into the frozen ground. Colonel
Howell's orders were for them to make a trench about four feet wide and
extending toward the river about twenty feet. It was to be twenty feet
deep alongside the pipe and in the form of a triangle, the long side to
incline toward the river. This was to facilitate the removal of the
gravel and dirt and to afford a path to the deep side of the trench where
it touched the gas tubing.

"Five feet from the bottom," explained the enthusiastic Paul, "we'll put
a shelf across the trench and we'll work from this, so that when a hole
is made in the pipe no one will be in danger from the rush of gas."

"That's right," added Colonel Howell. "All the gas can't get out through
the new opening, but enough of it ought to escape to make it possible to
work on the top opening. But we'll hardly finish the ditch before the
boys get back?"

"Hardly," smiled the happy Paul. "They ought to be here before dark."

While Ewen and Miller were busy with picks and shovels, Colonel Howell
and Paul devoted themselves to improvising the long wooden handle for the
chisel to be used in cutting the pipe. But the workmen had