ng.
"But what does it mean? I ain't got that at-tall!"

"Nor I!" snapped Drew. "We're only getting deeper and deeper into
facts. After a while we'll have enough of them to solve the case. The
smooth bullet is important. It suggests many things--a home-made gun,
for instance."

"Might have been an old Civil War gun, Chief."

"I don't believe there was anything like that in Stockbridge's house.
You might inquire when you go up. He was very modern with his Flying
Boat stock and his improved munitions for the Allies. He has no old
collection of arms."

Delaney stared at Harrigan. Drew swung to his desk and tapped the
blotter for a moment. "We'll get busy," he said briskly, as he swung
back again and faced the two operatives. "I've almost got my man. That
bird there," Drew pointed toward the magpie, "is our one best bet and
lead. I may be wrong, but I'll wager a good cigar there's a convict or
ex-convict at the back of this case. How else can we explain 'Ossining'
or 'Ah, Sing' repeated through the magpie to us. It's not an impossible
clue. It might happen. Let's move with both feet!"

Delaney rose lankily and stood by the door. He braced his shoulders,
then shelved them forward as he reached a finger toward the bird-cage.
"Pretty Poll!" he said.

The magpie darted about the cage like a shaft of blue light. It came to
rest with its tail feathers thrust through the bars. It peered with
beaded eyes at Drew who had snatched up a bundle of papers and was
sorting them.

"Get busy, Delaney, on this assignment!" he said sharply. "Waste no
time. Run up to Stockbridge's and get me plaster-paris casts of all the
footprints you can find around that junction box. It's stopped
snowing," he added, glancing out the window.

"All right, Chief."

"Wait a minute. Stop somewhere on your way up-town and find out the
exact temperature changes last night. What I want you to get is a
record of every quarter-hour, so as to show when the early, packed snow
in Stockbridge's yard froze solid. The under crust!"

"I got that in my head, Chief! That's my idea, exactly. If a tall lad
tapped in on the junction box early in the night his footprints will be
frozen close to the ground. The whole surface is level now, but there
ought to be ice-posts sticking up when I get done thawing."

"That's right! You'll probably find the trouble-hunter's and one other
set of prints. The other set is our man's!"

"What size feet did the trouble-hunter have