ee. Would you mind telling me the object of the
whole thing?"

"Not at all. I plan to make a permanent record of the work of the most
ingenious bank robber in the world. I hope he keeps his word."

"What do you mean?"

"Three days ago when Sturtevant sweated a 'confession' out of poor
Winston, the bank got a message that the robbery would be repeated this
morning and dared them to prevent it. Rogers thought it was a hoax, but
he telephoned me and I worked the Bureau men night and day to get my
camera ready in time for him. I am afraid that I can't do much to
prevent the robbery, but I may be able to take a picture of it and thus
prevent other cases of a like nature."

"Was the warning written?"

"No. It was telephoned from a pay station in the loop district, and by
the time it was traced and men got there, the telephoner was probably a
mile away. He said that he would rob the same cage in the same manner as
he did before."

"Aren't you taking any special precautions?"

"Oh, yes, the bank is putting on extra guards and making a lot of fuss
of that sort, probably to the great amusement of the robber."

"Why not close the cage for the day?"

"Then he would rob a different one and we would have no way of
photographing his actions. To be sure, we will put dummy money there,
bundles with bills on the outside and paper on the inside, so if I don't
get a picture of him, he won't get much. Every bill in the cage will be
marked as well."

"Did he say at what time he would operate?"

"No, he didn't, so we'll have to stand by all day. Oh, hello, Casey, is
everything all right?"

"As sweet as chocolate candy, Doctor. I have tested it out thoroughly,
and unless we have to run it so long that the film wears out and breaks,
we are sitting pretty. If we don't get the pictures you are looking for,
I'm a dodo, and I haven't been called that yet."

"Good work, Casey. Keep the bearings oiled and pray that the film
doesn't break."

* * * * *

The bank had been opened only ten minutes when the clangor of gongs
announced a robbery. It was practically a duplicate of the first. The
paying teller had turned from his window to take some bills from his
rack and had found several dozens of bundles missing. As the gongs
sounded, Dr. Bird and Casey leaped to the camera.

"She snapped, Doctor!" cried Casey as he threw two switches. "It'll take
an hour to stop and half a day to develop the film, but I