“Look out, you’ll overbalance!” called Tom.

But the good advice came too late.

Without the slightest warning to give them a chance to save him, Dick Donovan’s body pitched over the side of the craft and fell like a stone downward through space.

For an instant the shock of the occurrence held them all spellbound. Then they woke into action with a series of shouts and cries that made inextricable confusion.

“Send us down! Send us down!” cried Mr. Chadwick.

“I daren’t,” declared Jack, “those creatures would certainly ram us.”

“Quick! Help him!” cried Tom, who had been leaning over watching the spot where Dick had vanished. It was not far from the place where the two monsters of the sea were battling, some two hundred feet beneath the flying ship.

Jack’s face was pale, but his manner was determined as he shut off the engine and ordered Tom to get out the grapnel rope. This was a rope some five hundred feet in length, of light but exceedingly strong fiber. At its end was a grapnel, a sort of four-forked anchor. The idea of it was to anchor the Wondership in case of a high wind or other emergency.

Tom produced the rope and Jack flung off his garments down to his underclothes. While he did this Tom had, in obedience to his chum’s orders, made the rope fast to an interior stanchion of the ship.

“See if you can spot him,” Jack said to Tom when the rope had been made fast.