A red glare suddenly enveloped the dirigible, showing her every outline.
“It’s a distress signal!” was the elder lad’s excited shout. “Something has happened.”
“I’ll tell the boys in the auto to answer it,” suggested Harry.
He sent out a sputtering wireless, which was soon answered by a blue glare from the auto. An answering illumination from the dirigible went up.
“They’ve seen our signal,” cried Frank. “Now, Harry, switch on the searchlight.”
“What for?”
“To pick out a landing-place by. I don’t want to risk our necks by dropping in the dark.”
“You are going to land and help them?”
“Of course; they may be in serious trouble. It is our duty to aid them.”
“But Slade’s machine?”