“Then for goodness sake give it a wide berth,” cried Jimsy; “if we keep on cruising about for a while we’ll be bound to land somewhere.  Anyhow we’ve got lots of gasoline, that’s one comfort.”

It was, indeed.  In the steady hum of their powerful motor the young aviators found consolation in that lonely ride through the billowing fog-banks.  At all events, there was no sign of a falter or skip there.

“If only we could get some wind,” sighed Jess.

“Might as well wish for the moon,” said Jimsy; “the air is as still as it used to be at noon out on the desert.”

“What a contrast between the Big Alkali and this!” cried Jess, half hysterically.  The strain of the white drifting fog was beginning to tell upon her.

Jimsy looked at her sharply.

“Look here, Sis,” he began and was going on when a sharp cry from Peggy arrested him.  At the same instant the Golden Butterfly swerved sharply, swinging over on her beam-ends almost.

Right in front of them, for one dreadful instant, there loomed the outlines of another aeroplane.  The next instant it was gone.  But the picture of the deadly peril, its outlines exaggerated by the mist, was photographed in the minds of every one of them.

“We must land somewhere, soon,” said Peggy, in rather a faint voice; “I don’t think I could stand many shocks like that.  Another inch, and——.”

She did not complete the sentence.  Her two listeners did not require her to.  It did not take a vivid imagination to have pictured the result of that “other inch.”

CHAPTER XXIII.

OUT OF THE CLOUDS.

Ten minutes or so later, a puff of wind blew the folds of fog apart for a brief instant.  Beneath them Peggy could see a sandy beach and some scrubby-looking brush.  Like a flash she took advantage of the momentarily revealed opportunity.  The Golden Butterfly, under her guidance, sank swiftly, grounding a few seconds later into a bed of soft sand.  It was like lighting on a pillow of down, so gently had the glide to earth been made.

Shutting off the engine, Peggy took hold of Jimsy’s outstretched arm and, followed by Jess, she jumped lightly out upon the sand.  The roar of the surf, as the big swells rolled upon the beach was in their ears.  A wholesome, stinging tang of salt in their nostrils.

“I wonder where on earth we’ve landed,” said Jimsy, looking about him; “perhaps this is some enchanted land and we are to face new perils—­dragons or something.”

“Well, gallant knight,” laughed Jess, in the highest spirits to be back on the firm ground again—­even if it was only shifting sand—­“we trust to you.”

“And by my troth,” exclaimed the mercurial Jimsy, “ye shall not be disappointed in me fair damsels.  Hullo! an adventure already.  Hark!”

Through the smother a dull sound was borne to their ears.  A sound that came in muffled but rhythmic thumps.  At intervals it paused, but then was resumed again.