“The water rises fast.  It’s over our ankles,” Hugh said quietly.

The bumping of a boat was again heard outside, then a trampling of feet, and all was still again.

“They have taken to the boats.”

Not all, however, for through the door there came a shout, “Goodbye, Master Holliday,” and a loud, jeering laugh.

“Au revoir, Sir Richard Fulke,” Rupert shouted back; “and when we meet next, beware!”

“Ha, ha! it won’t be in this world;” and they heard their enemy get into the boat.

“Now, Hugh, we must set to work; we have got the boat to ourselves.”

“But what are we to do, Master Rupert?”

Rupert was silent for a minute.

“There is but one way, Hugh.  We must blow up the boat.”

“Blow up the boat!” Hugh repeated, in astonishment.

“Yes, Hugh.  At least, blow the deck up.  Give me that keg of powder.”

Hugh opened the locker.  It was, fortunately, still above water.

“Now, Hugh, put it in that high locker there, just under the deck.  Knock its head out.

“Now tie a pistol to those hooks just above, so that its muzzle points at the powder.

“Now for a piece of cord.”

“But it will blow us into smash, Master Rupert.”

“I hope not, Hugh; but we must take our chance.  I would rather that than be drowned gradually.  But look, the water is up nearly to our waists now; and the boat must be pretty nearly sinking.  I will take hold of the cord.  Then both of us throw ourselves down to the floor, and I will pull the string.  Three feet of water over us ought to save us; but mind, the instant you feel the shock, jump up and rush for the opening, for it is pretty sure to sink her.

“Now!”

The lads dived under water, and the instant afterwards there was a tremendous explosion.  The deck of the boat was blown into the air in a hundred fragments, and at the same moment the boat sank under the water.

A few seconds later Rupert and Hugh were swimming side by side.  For a while neither spoke—­they were shaken and half stunned by the shock.

“It is a thick fog, Hugh.  All the better; for if those scoundrels come back, as is likely enough, there is no chance of their finding us, for I can hardly see you, though I am touching you.  Now we must paddle about, and try to get hold of a spar or a bit of plank.”

Chapter 12:  The Sad Side Of War.

Before firing the keg of powder, Rupert and Hugh had rid themselves of their jackboots, coats, and vests, and they therefore swam easily and confidently.

“Listen, Hugh!  Here is the boat coming back again,” Rupert exclaimed.  “This thick mist is fortunate, for they can’t see twenty yards.  We can always dive when they come near.  Mind you go down without making a splash.  We are all right at present; the boat is going to our right, let us swim quietly in the other direction.”