casting of a steel rifled cannon that would be fifty inches
across at the muzzle, and making it a hundred feet long. I mean
it could be done on paper--figured out and all that. But whether
you would get a corresponding increase in power or range, and be
able to throw a relatively larger projectile, is something no one
knows, for there never has been such a gun made. Besides, the
strain of the big charge of powder needed would be enormous. So I
don't want merely to make a giant cannon. I want one that will do
a giant's work, and still be somewhere in the middle-sized
class."

"I see. Well, you'll probably get some points at Sandy Hook."

"I think so. We go day after tomorrow."

"Is Mr. Damon going?'

"I think not. If he does I'll have to get another pass, for
mine only calls for two persons. I got it through a Captain
Badger, a friend of mine, stationed at the Sandy Hook barracks.
He doesn't have anything to do with the coast defense guns, but
he got the pass to the proving grounds for me."

Tom and his chum talked for some time about the prospects for
making a giant cannon, and then the young inventor, with Ned's
aid, made some powder tests, using some of the explosive that had
so nearly caught fire.

"It isn't just what I want," Tom decided, after he had put
small quantities in little steel bombs, and exploded them, at a