"I've been under greater pressure than that," Danny chirped.

"When you were shot?" Bink asked. "All guns, big and little, are under pressure when they are shot."

"I'll put your throat under pressure when we get away from here!" Bink threatened.

"This is a twelve-inch rifle, loaded with one hundred and thirty pounds of powder and a projectile of the same weight as the first."

The party had moved to a new point, and Captain Heath was again talking. Other guns were fired, after the discharge of this one; the last shot being sent from a twelve-inch rifle with a charge of four hundred and seventy-five pounds of Dupont brown prismatic powder and a projectile weighing one thousand pounds.

The roar, the jar, and the vibration were like that of a miniature earthquake. Captain Heath's calm voice was heard again, after a short silence.

"The velocity was two thousand and eighty-eight feet per second, and the pressure four thousand pounds. This pressure is ten thousand pounds too high. The powder is too quick, and will be condemned."

After this there was an examination of the guns and carriages, with a lecture by Lieutenant Bell; an examination of the gun-lift battery and the hydraulic lifts, and the wonderful Buffington-Crozier disappearing-carriages, and a look over the site of the new artillery post to be known as Fort Hancock. Then luncheon was served.

In spite of the many interesting things which he had seen and to which he had listened, Merriwell could not get his thoughts away from Barney Mulloy. He had already obtained consent for the party to be taken on the launch to Sea Cove and Glen Springs at once, after luncheon. Thinking of these things and with his head full of the plans for discovering the secret of the happenings at Glen Springs, he walked round the works again, viewing the emplacements and the big guns, but with his thoughts far enough away from the things on which his eyes rested.

Suddenly he was attracted by a cry. It seemed to come from the air, and it made him think of the apparition and the ghostly footsteps. But when he glanced up he saw Danny Griswold's head protruding from the muzzle of a large coast-defense cannon. Merriwell was astonished, though such a piece of recklessness was just like Danny. It was not that Frank feared any peril to Danny from the gun, but the officers and gunners would be indignant, no doubt, if they caught the little joker playing hide-and-seek in that way with one of their pets.