uld be there, for I've been trying to learn what
quantity of water we have got on board. As far as I can make out, we've
not got a gallon at the most, and that won't keep our tongues moist for
more than a couple of days."

"I doubt whether the master himself is aware of this," said Tom, "for he
takes the matter very easy, and he ought to have put all hands on an
allowance before this. He must do so, or we shall be dying of thirst
before we drop anchor in Sydney harbour."

The brig was at this time under all sail, but the wind was light, and
she was making little way. Suddenly her sails gave a loud flap against
the mast.

"We are going to have another calm, I fear," said Desmond.

"I'm not quite so sure of that," said Casey. "I've been watching the
sky, and it seems to me as if a thick gloom was spreading over it. I've
observed a dark bank rising rapidly to the southward and eastward.
Look, sir, you cannot see a star in that quarter. If I was the mate,
I'd shorten sail at once."

Tom and Desmond took a survey of the horizon in the quarter to which
Casey was pointing. The bank was rising rapidly; it looked, indeed, as
if a dark curtain was being drawn over the sky.

"I'll point it out to the mate," said Tom.

On going aft, Tom found the mate seated close to the taffrail. Instead
of keeping a look-out, he was fast asleep. Tom roused him up, and
pointed out the appearance of the sky.

"I don't think it's anything," he observed, rubbing his eyes.

"It is, though," cried Tom. "Listen to that roar."

At that moment a dull rushing sound was heard, and a long streak of
white was seen extending from east to south-west across the ocean.

"Turn the hands up! shorten sail!" cried Tom.

The mate repeated the order. The midshipmen sprang to the main-topsail
halyards, Casey and Peter to the fore-topsail; but almost before a rope
could be let go, a fierce blast struck the brig. In vain the mate tried
to put the helm up. Over she heeled more and more, until the yardarms
touched the water. Tom and Desmond seized hold of Billy, who had just
before dropped off to sleep, and scrambled up to the weather bulwarks.
Casey and Peter had been doing the same. Another instant and the brig
was on her beam ends, with the water rising up to the combings of the
hatchway.

Believing that the brig was going over, the midshipmen and their
companions got on to the outside of the bulwarks, holding on to the
main-chains. As the