As the explosion would be under the bow, it was deemed best to get as far away as possible.

So all went to the stern.

Frank waited for a moment when the boat was steady in its rocking. Then he pressed the electric key.

There was a sudden shock, a muffled roar, and the Dolphin heaved and pitched violently.

Then a great column of water shot up abaft her bows, and she was perceptibly lifted and hurled back.

“Hurrah!” cried Frank, with the wildest of joy. “She is off the reef!”

The others gave a great cheer. It was too good to believe.

But it was the truth, just the same. The Dolphin was off the reef.

Frank sprang into the pilot-house and pressed the motive lever. She backed away, and answered her helm readily.

For a moment the spirits of the voyagers were indeed high.