ossible.

The submarine was held fast in the grip of the long, sinuous, snake-like
fingers of the terrible sea grass. Weak as one strand was, the thousands
combined served to fasten the ship as securely as wire cables would have
done. The weeds had entangled themselves all around the craft and
refused to let go.

"Well," remarked Mr. Henderson when all efforts had failed. "We must
think of a new plan."

He spoke cheerfully, for he did not want the boys and other members of
the crew to know how worried he was. This was a danger he had never
counted on when he planned to go to the south pole.

"There is no great hurry," Mr. Henderson went on in a few minutes. "We
can stay here for several days if need be, and by that time a storm may
tear the grass loose."

"If we had our old hay sythes here," spoke Bill, "me an' Tom could put
on divin' suits an' go out an' cut the sea weed."

"I'm afraid that wouldn't work," answered Mr. Henderson. "I'll think up
some plan, soon."

He started toward the engine room to look over the machinery. He was met
by Washington, who seemed much alarmed.

"What's the matter?" asked the inventor.

"De air tank hab busted an' all de air is escapin' out!" cried the
colored man. "We'll all smothercate!"

CHAPTER XII

FIRE ON BOARD

The professor jumped past Washington and hurried into the room where the
tanks were kept, carrying the reserve supply of air for breathing when
the ship was under water. A loud hissing told that the leak was a large
one.

"Quick! Bring me some tools and a steel plug," shouted the captain.

Mark hurried in with the things the professor wanted. But before the
plug could be put in the hole the air stopped hissing.

"The leak is fixed!" cried Jack.

"No," said the professor in a strange voice.

"But the air no longer rushes out."

"For a good reason, there is no longer any air to rush out. It is all
gone!"

"Do you mean to say that all the reserve stock has been lost?" exclaimed
Andy.

"I fear so. The leak must have been a bad one. The air was stored in
tanks under pressure, and, as you know, we released it as we needed it.
Now it is all gone."

"All? Then we shall smother," said Jack, and his voice trembled.

"Not at once," went on Mr. Henderson in a calm voice. "There is enough
air in the entire ship, including that which has leaked from the tanks
to last us five hours. After that----" he paused and looked at his
watch.

"Well?" asked