owing wiring
diagrams which were far worse than any clue he had ever attempted.

"A telephone engineer," he said half aloud. "A man who could trace out
this stuff ought to make a mighty fine detective. I never saw such a
snarl. Now what does hysteresis and laminations mean? What's the idea
of having an alternating current of low voltage on the same line with a
talking current of three volts? I don't see how they can get two
currents on one set of wires. Maybe they don't."

He tossed the book to the table in front of him and rose with a frown.
This frown changed to a wrinkled furrow of half amusement as he hurried
back to the little prim lady.

"Too deep for me," he said, referring to the book she had given him.
"That may be a beginner's treatise, but I'm in the kindergarten class
in electricity. What's a micro-volt?"

"I'll look it up, sir," she said.

"Never mind. I wouldn't know, after you did. Suppose you get me a book
on magpies."

The librarian fingered her files. "Try Birds of England," she
suggested, coming from behind her desk and gliding like a pale shadow
over to a book-case. "Try this. It's complete. You'll find magpies and
starlings and piemags and any number of plates of six colors in this
splendid volume."

"The one that interested me was black as a crow," he said, as he turned
toward his alcove. "Perhaps there are white magpies as well as white
crows. I never saw one, though. My bird's a deep one."

The little librarian stared after Drew's vanishing form with a slight
pucker between her eyes. For a man of his solid respectability, the
series of actions were strange indeed. She sat down and wondered if he
was a moving picture editor trying to connect black magpies and
telephones.

Drew appeared in two minutes. He leaned over the desk and startled the
lady with a request for anything pertaining to guns and projectiles.
These she had in plenty. A great many war books had been purchased
during the period which followed America's declaration.

The detective erected a breastwork with the books she brought. He
conned them with understanding until he came to ballistics and
trajectory. He stopped there. He rose. His brain was crammed with fact
upon fact. He had the formulae of smokeless powder and the analysis of
cupronickel bullets. He had absorbed muzzle velocity and angle of fire.
He fairly bubbled over with good humor as he thrust his hands into his
overcoat, caught up his hat and started out the