n which the murder had
been covered up in a score of details, all pointed to a criminal mind
of the cunningest order. It savored of practice in crime and study of
natural conditions. Its bizarre features placed it out from other
crimes and raised it to a class of its own.

The snow which impeded the detective's steps, in some manner cleared
his brain. He began to review the series of events. He boxed the case
with returning shrewdness. He went over the points like a sailor
repeating the compass-chart. He even saw a light.

This light was a star that guided him around a corner and then along
the long reach of a white-mantled street where children shrilled and
played. Snow-balls flew past his head. Sleighs and muffled taxis
churned by. Women in furs and heavy cloaks glanced up at his olive face
from which peered sanguine eyes bent upon a known destination.

He paused at the foot of a flight of steps leading to a library. In
this building he knew there would be on file certain data concerning
three links of the chain which he was trying to forge about the
criminal or criminals who had slain Stockbridge.

He entered the storm-door, shook the snow from his coat, and removed
his hat with a swinging bow as he drew erect in front of a prim lady at
a desk.

"I want all the books you have on modern telephony," he said with a
winning smile. "I'm sure that you have one or two."

The prim lady who knew a gentleman when she saw one, raised her brows
and rapidly thumbed over a filing-card system.

"One or two," she repeated. "Why, we have over twenty. Now just what
branch of Telephony do you want? There are a number of divisions in the
subject. We have Smith on Central Office practice. We have Steinward on
Induced Currents in Relation to Magnetism. We have Oswerlander on
Switchboards and Carbon Transmitters. We have Burke on Circuits and
Batteries. We have----"

"Hold on, please," said Drew, catching his breath. "I better try
something easy. One of those Juvenile books with simple diagrams and
switchboards or junction-boxes."

Drew carried the book to an alcove which was deserted. He took off his
coat, hung it on the back of a chair, upended his hat and sat down with
a tired smile. Soon he was busy in the mystery of electricity in
relation to the telephone. He conned over the pages. He browsed along
like a novice trying to understand trigonometry. He frowned over such
terms as micro-ampere and micro-volt. He grew dizzy foll