The young inventor returned on the run to the electric cannon. There was a whirr of machinery, and the Advance moved forward. She increased her speed, and the two watchers in the stern loked anxiously out of the windows to see what their rivals would do.
For a moment no movement was noticeable on the part of the Wonder. Then, as those aboard her appeared to realize that the craft on which they depended to pilot them to the sunken treasure was slipping away, word was given to follow. The ship of Berg and his employers shot after the Advance.
"Here they come!" cried Captain Weston. "They're going to ram us again!"
"Then I'm going to fire on them!" declared Tom savagely.
On came the Wonder, nearer and nearer. Her speed was rapidly increasing. Suddenly she bumped the Advance, and then, as if it was an unavoidable accident, the rear submarine sheered off to one side.
"They're certainly at it again!" cried Tom, and peering from the bull's-eye he saw the Wonder shoot past mouth of the electric cannon. "Here it goes!" he added.
He shoved over the lever, making the proper connection. There was no corresponding report,
