t work out in theory.

"And you must remember that the gun, if gun it is, couldn't be in the
very first German line," said Tom, who had studied ordnance. "It must be
at least ten miles back, to allow for sufficient protection from the
French guns. That would make it shoot about seventy-two miles, and I
don't believe any gun on earth could do it!"

"Neither do I," added Jack. "We've got to dope out something else. But
this isn't finding your father, Tom."

"I know it, and I don't mind admitting I'm clean discouraged about him,
Jack. If he's alive why doesn't he send me some word? He must know where
I am, and, even if he doesn't know I'm in Paris, they would forward any
message he might send to our aeroplane headquarters."

"That's right. But what are you going to do about it?"

"I hardly know. He may still be in Paris, but it's such a big city that
it's hard to find him. Then, too, I'm thinking of something else."

"What's that, Tom?"

"Well, dad may not want us to know where he is."

"Why in the world would he want such a thing as that?"

"Well, he might be followed, or bothered by spies. Perhaps he has come
over to do some special work for the French or English army people.
Maybe a spy was after him just before the big German gun wrecked his Rue
Lafayette house. He may have considered this a good chance to play dead,
and that's why he doesn't send some word to me."

"That's a good theory. But it isn't very comforting."

"No, but there isn't much comfort in war times. We've got to make the
best of it."

"I guess you're right, Tom. Now do you want to go look at the latest
work of the Hun?"

"Might as well. The bombardment seems over for the night."

"I wonder why it is they don't fire after dark."

"Probably afraid of giving the location of their cannon away by the
flashes. They'd be seen at night; but during the day, if they used
smokeless powder, or a smoke screen in case they can't get smokeless
powder for such a big gun, it would be hard to locate the place where
the shots come from. So we're comparatively safe after dark, it seems."

Later this was not to prove to be the case, but it was when Tom spoke.

The boys went to the section of the city in which the last shells had
fallen. While comparatively little damage had been done, a number of
persons had been killed and injured, children among them. Some fragments
of the shells were picked up, but not enough to make certain any
particular theory in