Suddenly there flashed over me the recollection of the marvellous invention that Kennedy had made for the Government just before his disappearance, as well as the memory of the experience I had had once with the intrepid Burnside.

Woodward’s face showed a ray of interest and hope in the overwhelming gloom that had settled on us all.

“You and Jameson go to Fort Dale, quick,” directed Arnold eagerly.  “I’m not fit.  Get Burnside.  Have him bring the torpedo in the air-boat.”

We needed no further urging.  It was a slender chance.  But I reflected that the submarine could not run through the bay totally submerged.  It must have its periscope in view.  We hurried away, leaving Arnold, who slowly mounted the hill again.

How we did it, I don’t know, but we managed to get to the Fort in record time.  There near the aeroplane hangar, sure enough, was Burnside with some other men adjusting the first real wireless Kennedy torpedo, the last word in scientific warfare, making an aerial torpedo-boat.

We ran up to the hangar calling to Burnside excitedly.  It was only a moment later, that he began to issue orders in his sharp staccato.  His men swarmed forward and took the torpedo from the spot where they had been examining it, adjusting it now beneath the hydroaeroplane.

“Jameson, you come with me,” he asked.  “You went before.”

We rose quickly from the surface and planed along out over the harbor.  Far off we could see the ripple from the periscope of the submarine that was bearing Del Mar away.  Would Kennedy’s invention for which Del Mar had dared so much in the first place prove his final undoing?  We sped ahead.

Down below in the submersible Del Mar was giving hasty orders to his men, to dip down as soon as all the shipping and the sand bars were cleared.

I strained my eyes through the glasses reporting feverishly to Burnside what I saw so that he could steer his course.

“There it is,” I urged.  “Keep on—­just to the left.”

“I see it,” returned Burnside a moment later catching with his naked eye the thin line of foam on the water left by the periscope.  “Would you mind getting that torpedo ready?” he continued.  “I’ll tell you just what to do.  They’ll try to duck as soon as they see us, but it won’t be any use.  They can’t get totally submerged fast enough.”

Following Burnside’s directions I adjusted the firing apparatus of the torpedo.

“Let it go!” shouted Burnside.

I did so, as he volplaned down almost to the water.  The torpedo fell, sank, bobbed up, then ran along just tinder the surface.  Already I was somewhat familiar with the wireless device that controlled it, so that while Burnside steadied the aircraft I could direct it, as he coached me.

The submarine saw it coming now.  But it was too late.  It could not turn; it could not submerge in time.

A terrific explosion followed as the torpedo came in contact with the boat, throwing a column of water high in the air.  A yawning hole was blown in the very side of the submarine.  One could see the water rush in.