“Well, at any rate, if the Sea Eagle never does anything more,” remarked Dr. Perkins, “she has accomplished a great deal.”

“I should think so,” exclaimed Frank, who had slipped into dry clothes as soon as the Sea Eagle took the air once more; “it isn’t every craft that finds her baptism in life-saving at sea.”

As long as they could see the Ultonia the big liner continued to blow her whistle, and doubtless the eyes of all her passengers remained fixed attentively on the wonderful sky ship as she waxed smaller and smaller against the blue. That afternoon the voyagers found themselves off Cape Ann. High above the cape they flew, cutting off a good chunk of distance in this way. The folks in West Gloucester stared in wonderment as the huge air ship soared by high above the town, and when a short time later the aviators passed above the white-winged fishing fleet, every tin pan and fog horn in the flotilla of small craft sounded an enthusiastic “God speed” to the air travelers.

Far behind the main body of the fisher craft lagged a small sloop, and as the Sea Eagle came closer to her the boys noticed that her flag was flying from the peak “union down,” a sign of distress the world over. The big hydro-aëroplane was flying low at the time, and it was easy to see, without the aid of glasses, that several men were running about the sloop’s decks and shouting something up at the air voyagers.

“Shall we go down and see what the trouble is?” asked Frank, as he and Harry saw the signs of distress.

“Yes,” decided the doctor, “no craft, either of the air or of the sea, can disregard such a signal of disaster. It will be odd if, for the second time on the very first day of our cruise, we are able to render aid to somebody who needs it badly.”

The boys thought so, too, and as they dropped seaward the minds of all three occupants of the Sea Eagle were busy with speculations concerning what could be the cause of the sloop’s distress. Dr. Perkins caused his craft to alight gently on the sea a short distance from the sloop, and then headed her over the waves toward the distressed vessel. As they drew closer they could see a grizzled-looking fellow, in rough fisher’s garb, leaning over the side.

“Come quick!” he shouted, “there’s been bad work going on aboard!”

CHAPTER XVIII.—AN ERRAND OF MERCY.

“What’s up?” cried Frank.