If the destroyer was going to get the submarine, now was the fatal
moment!

The _Dewey_ suddenly lunged like a great tiger leaping from the limb
of a tree upon its prey. Responding to a signal from his commander,
Chief Engineer Blaine had suddenly shot into the submarine's engines
the full power of the electric storage batteries and hurled the
_Dewey_ forward with a great burst of speed. There was a slim chance
that the swift-moving German warship might be sidestepped by a quick
maneuver, and the crafty McClure was leaving no deep-sea trick unturned.

"Nice place for the Fritzes to swing overboard one of those infernal
depth bombs," muttered Bill Witt.

A depth bomb! Jack and Ted knew all about the latest device being
employed by the warring nations in their campaigns against submarines.
Gigantic grenades, they were, carrying deadly and powerful explosives
timed to go off at any desired depth. One of them dropped from the
deck of the destroyer as it passed over the spot where the _Dewey_
had submerged might blow the diminutive ship to atoms.

With reckless abandon big bluff Bill Witt began to sing:

_"It's a long way to Tipperary, It's a long way to go. It's a long
way---"_

The song was interrupted by a harsh grating sound---the crashing of
steel against steel---and then the _Dewey_ shuddered from stem to
stern as though it had run suddenly against a stone wall.