And Frank almost held his breath awaiting the verdict.

Suddenly he saw Jerry start, and screw the glasses more eagerly to his eyes, as he craned his neck to see the better.  With the increasing wind the waves had commenced to rise a little, consequently any floating object might at times be difficult to discern.

“I had a glimpse of something then, fellows!  But, after all, it might have been another bunch of old pelicans!” he exclaimed.

“Not that.  Pelicans would not be so far out.  They hug pretty close to the shore, where the water is more shallow, and the fish come in to feed.  Still, it may have been the fin of a shark cutting the water like that one—­” started Frank, when Jerry interrupted him: 

“There it is again!  As sure as you live, I believe it’s a man clinging to some sort of wreckage!  Here, take the glasses, Frank!  Right over there, dead ahead!  Now be ready!  There!  See?”

“It is a man!  Yes—­two of them!  Fellows, we are in time!” cried Frank.

“Hurrah!” the others shouted in chorus.

And the breeze, coming off shore, must have carried that volume of cheering sound to the ears of the almost despairing balloonists as they clung there to the wreck of their disabled air craft, possibly arranged to float for a time if it dropped into the sea.

“Yes.  There!  I can see one of them waving his hand!  Give the poor chaps another shout, boys!  This is great luck for us!” exclaimed Frank, and his own sturdy voice helped to swell the sound that rolled over the water.

If it was a happy moment for the rescuers, imagine the feelings of the two who clung there, expecting that every minute might see them without any support, as the waterlogged balloon sank under them!

Fast though the motor-boat was shooting through the waves, she seemed to fairly crawl, such was the impatience of the young voyagers.

So they swept alongside the floating balloonists.  When Professor Smythe discovered the identity of those who were coming to his aid his astonishment knew no bounds.  It was the most remarkable coincidence he could remember meeting with in an adventurous career extending over many years.

“Was that your camp we passed over, a little while back?” he asked, as, having been helped aboard, and some instruments being passed up by his assistant, he helped the latter to crawl over the gunwale of the motor-boat.

“Just what it was,” laughed Frank, “and you came near wrecking us, too.  The sand bag struck the tent, and carried it down in a heap.”

“Incredible!  And yet that very fact goes to prove my assertion that in war time dynamite could be easily dropped into a fortress by means of a dirigible balloon, or an aeroplane.  That was a happy thought of mine to send a message.  Only I hope none of you brave boys received any injury!” cried the professor.

“Luckily not.  But what is to be done with this wreckage?” asked Frank.