chloroform having passed away. He had breathed the fumes of it for
only a little while, so no harm had been done. He and Ned made an
examination of the shop, but found nothing missing.

There were no traces of the intruders, however, though the two
chums looked carefully about outside the building.

"You were too quick for them, Ned," said Tom. "You came as soon as
I called. They heard me speaking, and must have known that I had
given the alarm."

"Yes, I didn't lose any time," admitted Ned, "but I didn't see a
sign of anyone as I ran up."

"They must have been pretty quick at getting away. Well, now to
decide what's best to do to-night."

After some consultation and consideration it was decided to set
the burglar alarms in every building of the Swift plant. Some time
previous, when he had been working on a number of valuable
inventions, unscrupulous men had tried to steal his ideas and
models. To prevent this Tom had arranged a system of burglar
alarms, and had also fitted up a wizard camera that would take
moving pictures of anyone coming within its focus. The camera
could be set to work at night, in connection with the burglar
alarms.

The apparatus was effective, and thus an end was put to the
efforts of the criminals. But now it seemed Tom would have to take
new precautionary measures. His camera, however, was not