to the boys, he set in the middle of
the floor a small, black box.

Just as he did that a soldier, evidently an officer of some kind in
the French army, stepped into the room, and in a mixture of French and
English asked if Professor Snodgrass was there.

"I am he," answered the scientist.

"Ah, zen you will please come with me," said the soldier. "You are
wanted at ze headquarters."

"Wanted at headquarters!" repeated the professor. "What for?"

"Zis will explain," and the officer handed a note to Professor
Snodgrass.

As the professor read it a smile came over his face.

"Ah, I understand," he said. "I will come at once. Boys, we will let
the insect pictures wait a minute. Perhaps you will be interested in
my latest discovery. Come, I am ready to go," and he picked up the
black box from the floor and stood in waiting.

The officer looked a little dubiously at the object in the professor's
hand, and then at the three boys.

"My orders did not include--_zem_!" he said, indicating Ned, Bob, and
Jerry, "nor--_zat_!" and he pointed to the box.

"This has to come," replied the professor. "It is part of what I
proposed. As for my friends, I will be responsible for them."

"Very well, sair!" and the Frenchman bowed and led the way.

Wonderingly the boys followed Professor Snodgrass, and presently found
themselves at field headquarters. A company of French soldiers were
standing about, and while waiting for the summons to the presence of
the headquarters officer who had sent for him, Professor Snodgrass set
down on the ground the black box he had brought.

Then he suddenly saw a curious insect crawling along and became intent
on its capture. The boys were watching him and paid no attention to
the black box until they heard some one yell:

"Look out, boys! It's an infernal machine in there--a bomb! He's a
spy and he's going to blow up the whole place. It's an infernal
machine--I can hear the buzzing of the battery inside."

An American soldier, who had approached the box and had leaned over to
inspect it, leaped away and began running as he cried out his warning.
There was consternation among the officers and men outside the
headquarters building, and Professor Snodgrass, pausing in his search
for the elusive insect, gazed up in surprise at the commotion.

"What has happened?" he asked.

"Some one says there's a bomb in that black box of yours," explained
Jerry.

"If there is, get it out of the way! Douse