"Ten," said Drew, turning it over and studying a penciled number.

"Ten," repeated the expert. "That is a print which was flashed on the corner of the little table which was overturned when Stockbridge fell to the floor after being shot."

"And the same man made it who made my prints in the booth?"

"The same!" declared the expert dryly.

"I don't see where you two are getting," said Fosd.i.c.k. "How could a man get into that library, shoot the old millionaire, get out again and go over to a slot-booth?"

"He might have been in the slot-booth first," suggested Drew with slow smiling. "From the booth he went to the house and killed Stockbridge."

"The fact is established," exclaimed Pope, "that the man you are after was in the library and in the booth. That's all you can say. There's no way to determine the exact hour these two sets of prints were made."

Drew lifted a second print. "No. sixteen," he said, turning to the expert. "Where was that made?"

Pope consulted his book. He glanced up at Fosd.i.c.k, who was ill at ease over the development in the case. "That," he said, swinging his eyes till they met Drew's, "that was made on the hardwood floor directly under Stockbridge's body. We found the print, with others of the little finger and middle finger when the coroner moved the corpse!"

The detective stared at Pope. "You mean," he said shrewdly, "that the man who made the prints in the booth and on the little table, also was down on his knees arranging Stockbridge's body, or doing something like that?"

"He made a distinct impression on the floor despite the fact that the body was moved over it. The polish and the varnish helped to hold this impression. I venture to say that it is there yet."

"Good!" said Drew. "I may have a look at it. I never went after prints in my investigation. I left that to men who knew their business--like yourself."

Pope smiled. He glanced at his book for a third time. "What's the number of that last print?" he asked.

"Forty-four!"

"Taken from the edge of the heavy door which was broken down by Delaney, I guess. Looks like his work."

"I had a hand in that," admitted Drew.

"This print was close to the k.n.o.b. There's none like it on the k.n.o.b itself."

"Umph!" declared Fosd.i.c.k.

Drew glanced at the commissioner. He smiled as he laid his hand on Fosd.i.c.k's shoulder. "I've got you to thank," he said, "for letting me use the brains and facilities of the police department. I think it clears the case in a remarkable manner."

"How?" asked the commissioner.

"Well for one thing," Drew said, lifting the third photo. "For one thing, we know that our man pa.s.sed through the doorway before or after the murder. He was in the library. He was in that booth which is a half mile or more away from the mansion."

"I'll grant you that, but what does it prove?"

Drew laid the photo on the table and turned toward the doorway. "It proves," he said, "that Stockbridge was murdered by a man who was never arrested in New York."

"That's a large order!" chuckled the commissioner. "There are a few good citizens and a number of bad ones we haven't got--yet!"

"I'm satisfied," said the detective, pulling his hat down over his head. "I'm going to look for a man who is too clever for his own good.

He's stayed out of your clutches. He's forgotten more about telephones than most men know. He's as slippery as an eel and as clever as the very devil. In one thing only did he err, so far in this chase."

"What's that?" asked the commissioner.

"He didn't wear gloves on the job. That's where we may trip him up."

"They all forget something," said Fosd.i.c.k, as Drew hurried out through the door with a bow toward the staring fingerprint man.

The detective hurried down the steps,--pa.s.sed the sergeant at the entrance, and turned up his coat collar as he plunged from the building and lowered his head beneath the down driving snow. The entire matter was as he had told Delaney. He would have to find who made the prints!

Deep, drifted snow barred his progress as he struck down through a towering canon and walked eastward. He had no coherent idea save the one that he wanted the grip of the open places in his lungs and the feel of freedom from stifling rooms and skeptical men.

The case had resolved itself into a battle of wits wherein the culprit who had murdered Stockbridge, by unknown means, had all the advantages.

He was unknown. He had the largest city in the world to hide himself in. He could strike at any time and in any quarter. Also, the detective realized, with a chilly oath, the murderer might already be fleeing the city for the south or west. It would be a natural thing for him to do.

Drew had one undisputed qualification for a detective. He was a worker.

He lacked the Latin sense of deduction, or the cleverness of a great operative who secured his men through quick brain work and shrewdness.

Hard work, and more work and still more work had won for him the little position he held in the city. He did not overrate his own powers. He had failed too often to hold himself too highly. Chance was a big factor in the criminal game. The members of the criminal tribe worked through luck and sheer audacity. Many escaped from the net and moved in the underworld until they made their final mistake which was probably so glaring it couldn't be overlooked.

Despite the fact that the finger prints were not of record, Drew held to the swirling conviction that the man he was after was of the criminal horde. There was much to lead him to this belief. The cleverness in connecting up the two telephone booths--the warning through the mail to Stockbridge--the manner in 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 cla.s.s 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 compa.s.s-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-b.a.l.l.s flew past his head. Sleighs and m.u.f.fled 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 following 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 amus.e.m.e.nt 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 cla.s.s in electricity. What's a micro-volt?"

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