e," said Craig proudly. "It was devised
by Bertillon himself, and he personally gave me permission to copy his
own machine. You see, it is devised to measure pressure. Now let's take
an ordinary jimmy and see just how much pressure it takes to duplicate
those marks on this door."

Craig laid the piece of steel on the dynamometer in the position it had
occupied in the safe, and braced it tightly. Then he took a jimmy and
pressed on it with all his strength. The steel door was connected with
the indicator, and the needle spun around until it indicated a pressure
such as only a strong man could have exerted. Comparing the marks made
in the steel in the experiment and by the safe-cracker, it was evident
that no such pressure had been necessary. Apparently the lock on the
door was only a trifling affair, and the steel itself was not very,
tough. The safe-makers had relied on the first line of defence to repel
attack.

Craig tried again and again, each time using less force. At last he got
a mark just about similar to the original marks on the steel.

"Well, well, what do you think of that?" he exclaimed reflectively. "A
child could have done that part of the job."

Just then the lights went off for the night. Craig lighted the oil-lamp,
and sat in silence until the electric light plant foreman appeared with;
the card-record, which showed a curve practically identical with that of
the night before.

A few moments later Professor Fletcher's machine came up the driveway,
and he joined us with a worried and preoccupied look on his face that
he could not conceal. "She's terribly broken up by the suddenness of it
all," he murmured as he sank into an armchair. "The shock has been too
much for her. In fact, I hadn't the heart to tell her anything about
the robbery, poor girl." Then in a moment he asked, "Any more clues yet,
Kennedy?"

"Well, nothing of first importance. I have only been trying to
reconstruct the story of the robbery so that I can reason out a motive
and a few details; then when the real clues come along we won't have
so much ground to cover. The cracksman was certainly clever. He used an
electric drill to break the combination and ran it by the electric light
current."

"Whew!" exclaimed the professor, "is that so? He must have been above
the average. That's interesting."

"By the way, Fletcher," said Kennedy, "I wish you would introduce me to
your fiancee to-morrow. I would like to know her."

"Gladly,"