"It does look as though he had an appointment with someone, Tom,"
suggested Ned. "His looking at the clock, and then going out, and all
that."

"Yes," admitted the young inventor, "and now I'm inclined to
change my theory a bit. It may have been some other airship than
mine that was used."

"How so?" asked Ned.

"Because the men who took mine were unprincipled fellows. Mr.
Damon would not have gone away with men who would steal an
airship."

"Not if he knew it," admitted Ned. "Well, then, let's consider two
airships--yours and the other that came to keep the appointment
with Mr. Damon. If the last is true, why should he want to go away
in an airship at midnight? Why couldn't he take a train, or an
auto?"

"Well, we don't know all the ins and outs," admitted Tom. "Taking
a midnight airship ride is rather strange, but that may have been
the only course open. We'll have to let the explanation go until
later. At any rate, Mrs. Damon, I feel sure that your husband did
go off through the air--either in my Eagle or in some other
craft."

"Well, I'm glad to hear you say so, Tom Swift, though it sounds a
dreadful thing to say. But if he did go off of his own accord, I