"I don't know," returned Tom, and then as he looked inside the
place, he breathed a sigh of relief.

"Oh, it's you, is it, Koku?" he asked, as a veritable giant of
a man came forward.

"Yes, master, it is only Koku and your father," spoke the big
chap, with rather a strange accent.

"Oh, is my father here?" asked Tom. "I was wondering who had
opened the door of this shed."

"Yes, Tom," responded the elder Swift, coming up to them, "I
had a new idea in regard to some of those side guy wires, and I
wanted to try it out. I brought Koku with me to use his strength
on some of them."

"That's all right, Dad. Ned and I came out to wrestle with that
recoil problem again. I want to try some guns on the craft soon,
but--"

"You'd better not, Tom," warned his father. "It will never
work, I tell you. You can't expect to take up quick-firing guns
and bombs in an airship, and have them work properly. Better give
it up."

"I never will. I'll make it work, Dad!"

"I don't believe you will, Tom. This time you have bitten off
more than you can chew, to use a homely but expressive