a bank of earth, by means of an electric primer.

"Why, Tom, that powder certainly burst the bombs all to pieces," said
Ned, picking up a shattered piece of steel.

"I know, but it isn't powerful enough for me. I'm going to send for
samples of another kind, and if I can't get what I want I'll make my
own powder. But come on now, this stuff gives me a headache. Let's take
a little flight in the Humming Bird. We'll go see Mr. Damon," and soon
the two lads were in the speedy little monoplane, skimming along like
the birds. The fresh air soon blew away their headaches, caused by the
fumes from the nitro-glycerine, which was the basis of the powder.
Dynamite will often produce a headache in those who work with it.

Two days later Tom and Ned set off for Sandy Hook.

This long, neck-like strip of land on the New Jersey coast is, as most
of you know, one of the principal defenses of our country.

Foreign vessels that steam into New York harbor first have to pass the
line of terrible guns that, back of the earth and concrete defenses,
look frowningly out to sea. It is a wonderful place.

On the Sandy Hook Bay side of the Hook there is a life-saving station.
Right across, on the sea side, are the big guns. Between are the
barracks where the soldiers live, and part of the land is given over to
a proving ground, where many of the big guns are taken to be tested.

Tom and Ned reached New York City without incident of moment, and,
after a night spent at a hotel, they went to the Battery, whence the
small government steamer leaves every day for Sandy Hook. It is a trip
of twenty-one miles, and as the bay was rather rough that day, Tom and
Ned had a taste of a real sea voyage. But they were too experienced
travelers to mind that, though some other visitors were made quite ill.

A landing was made on the bay side of the Hook, it being too rough to
permit of a dock being constructed on the ocean side.

"Now we'll see what luck we have," spoke Tom, as he and Ned, inquiring
the way to the proving grounds from a soldier on duty, started for
them. On the way they passed some of the fortifications.

"Look at that gun!" exclaimed Ned, pointing to a big cannon which
seemed to be crouched down in a sort of concrete pit. "How can they
fire that, Tom? The muzzle points directly at the stone wall. Does the
wall open when they want to fire?"

"No, the gun raises up, peeps over the wall, so speak, shoots out its
projectile, and then crou