In a twinkling Ensign Dave had shaken hands with the birdman, adding:

"At your orders, sir!"

Then Dave stepped nimbly up to the platform. "Take a seat beside me, with your field-glasses ready. Here's your field note-book."

At a sign from Lieutenant Bowers, the eager sailormen parted in front of the airship, which, after a brief run, soared gracefully once more.

Behind Lieutenant Bowers stood a sailor with a signal flag.

"Step to the rear," Bowers directed, over his shoulder, "and wigwag back: 'O.K. Stopped only for assistant.' Sign, 'Bowers.'

"Aye, aye, sir," answered the signalman. "Lieutenant Sherman's airship is rising from the harbor, sir," reported the signalman.

"Very good," nodded Lieutenant Bowers, and kept his eyes on his course. "Darrin, are you taking all the observations necessary and entering them?"

"Aye, aye, sir."

"There's the railroad bridge about which the admiral was so anxious," said Bowers, presently. "You will note that the bridge stands, but the railroad tracks have been torn up."