"business" was more or less of a joke among his friends.

So then, a few days after the departure of Mr. Peterson, Tom
and Ned sat in the former's office, discussing the young
inventor's latest scheme.

"How big is the biggest gun ever made, Tom?" asked his chum. "I
mean in feet, in inches, or in muzzle diameter, however they are
measured."

"Well," began Tom, "of course some nation may, in secret, be
making a bigger gun than any I have ever heard of. As far as I
know, however, the largest one ever made for the United States
was a sixteen-inch rifled cannon--that is, it was sixteen inches
across at the muzzle, and I forget just how long. It weighed many
tons, however, and it now lies, or did a few years ago, in a
ditch at the Sandy Hook proving grounds. It was a failure."

"And yet you are figuring on making a cannon with a muzzle
thirty inches across--almost a yard--and fifty feet long and to
weigh--"

"No one can tell exactly how much it will weigh," interrupted
Tom. "And I'm not altogether certain about the muzzle
measurement, nor of the length. It's sort of in the air at
present. Only I don't see why a larger gun than any that has yet
been made, can't be constructed."

"If anybody can invent one, you can, Tom Swift!" exclaimed Ned,
admiringly.