"h.e.l.lo! h.e.l.lo! You big copper! Shout on! See how loud you can curse me!

That's it. That--is--it!"

Drew heard Delaney's voice rise in indignation. The taunt had spurned him to greater effort. The metallic diaphragm of the receiver roared and clicked. It echoed the voice. It stopped. It vibrated again. It reached a reed-like tune of high-pitched anger. The prisoner closed his eyes and stiffened. He pressed the receiver directly over his ear. He drew back on the chain and to one side. Drew's face darkened with suspicion. It was too late. The detective had time to spring away as a cone of lurid light and flame shot out from the telephone diaphragm and splashed across the prisoner's set face. A sharp detonation racked the perfumed air of the room. Smoke wreathed about the astonished Inspector's head, and floated upward toward the ventilator.

Cuthbert Morphy's muscles relaxed. He spun, sank to his knees, then pitched forward across the rug with a bullet in his brain. Drew untwisted the chain with a wrist flip, sprang forward toward the cheval-gla.s.s, and stamped his foot down upon the smoking telephone receiver as if it were the head of a rattlesnake.

He turned with clear light striking out from his eyes. He nodded toward the leaning form of the girl and the erect one of the captain. He divined in seconds how the murder of Montgomery Stockbridge had been accomplished. The full series of events and clues flashed through his brain. It was like an orderly array seen at a picture show.

Cuthbert Morphy, guised as a trouble-hunter in the employ of the telephone company, had devised a single-shot pistol out of a telephone receiver and had caused it to be actuated by the human voice so that it would always strike in the most vulnerable part of man's anatomy--the ear.

With this lethal instrument he had slain the millionaire, and, when trapped and in danger of execution, he had employed the same method to bring about his own death. It was a fitting end to a life of crime and drug-brought imageries.

Delaney, with drawn gun and wild of eyes, burst through the tapestries and brought up with a dizzy lurch before the body of Cuthbert Morphy.

He stammered and glared downward. He swung his heavy chin and stared at Loris and Nichols in the gloom of the further curtains. He clapped Drew on the shoulder with a heavy hand.

"Had to shoot him, eh, Chief? What'd he try? What--you got your foot on?"

"An electric pistol," said Drew, with a grim smile distending his olive-hued lips. "An infernal machine, Delaney. I hope it isn't a repeater. Cut that wire! Both wires! Get your knife out and cut through them, quick! I won't take any chances."

The big operative pocketed his revolver with a back swing of his right hand, brought it forward empty and ran it down his trouser pocket. He brought out a buck-horn jack-knife, pried it open, stooped and slashed through the two silk cords holding the receiver to the bottom of the transmitter which had fallen from the bracket.

Loris swayed with supple limbs. She raised her hands and pressed her unjeweled fingers against her face. She sobbed once, then turned and threw herself upon Nichols' drab shoulder. "Harry," she cried. "Oh, Harry--what happened? I didn't see what happened!"

The captain glided an arm about her waist and half-carried, half-led her to a couch in the reading-room. "Rest here a minute," he said, leaning down. "Be cool and as brave as you can. The trouble-man won't trouble you any longer. He took his own medicine!"

Nichols returned to the sitting room in time to hear Drew exclaim, after Delaney had reached down and lifted the receiver, "The case is closed! This closes it with a bang! Give me that electric pistol, Delaney!"

The operative handed it over. "Get a big rug," ordered Drew with sudden thought. "Cover that fellow over till we call the Central Office men and the coroner. I want to examine this receiver."

"Right here on this little table would be a good place," suggested Nichols, lifting off a handful of ivory ornaments and depositing them on top of a gla.s.s case. "I'll spread a paper here. I'd like to see what's inside that thing myself."

"Do you know anything about electricity or telephony?" asked Drew, as he turned the hard-rubber receiver in his hand and stared at the listening end.

"Very little, Inspector. But fire-arms are in my line and that seems to be one."

The detective nodded. "It's one, all right," he said, holding it out with a steady hand. "Looks harmless, don't it? Two binding-posts on one end. A rubber cap on the other. Notice that diaphragm."

Nichols took the receiver and squinted at the rubber cap. "By George!"

he said. "This is odd. There's a tiny hole drilled or punched in the center. It's about the same size as the bore of a twenty-two caliber revolver."

"Look at your hands!" said Drew. "What the devil," he added with dawning conviction. "Say, Delaney, do you remember that spot of black under my left ear. The one you noticed after we left yesterday morning?

The----"

"Sure, Chief. That's where you got the s.m.u.t--from that receiver!"

"I got it when I picked up the telephone in the library downstairs and tried to get Central. Do you remember how long she took? This is the same receiver in all probability. The trouble-hunter removed it from the library connections, loaded it, and brought it up here. It looks like any ordinary receiver. The telephone company have some with binding posts and some without. This is an earlier model."

"The spot of black was from the first discharge when Stockbridge was killed!" exclaimed Delaney.

Drew ran his fingers around the inner rim of the rubber cap. He held them up. "See!" he exclaimed. "No wonder my neck was marked. That settles that mystery, Delaney. If we had any brains at all we would have connected the soot and the telephone. If we had done that we'd have solved the case early this morning, or yesterday morning. It's after one, now!"

"This hole," said Nichols, "was the only thing in the whole dastardly scheme that could have been seen. It's the size of the end of a lead pencil. Funny you didn't notice it?"

"I looked everywhere but there," admitted Drew. "The receiver hangs with the diaphragm end down. That's the reason I didn't see it.

Well--there's always a reason," he added. "Now, Delaney, fetch me that trouble-hunter's satchel. We'll see what this pistol is made of and how it is made. I venture to say that it is simple."

Delaney awoke from his stupor and lifted a rug which he tossed over the body of Cuthbert Morphy. He wiped his hands with a finite motion. He wheeled and slouched lankily across the polished floor. He returned with the lineman's kit.

"Pliers," said Drew, as the big operative removed the straps and reached his hand inside. "I saw a pair there when we had it open before," the detective added, uns.c.r.e.w.i.n.g the rubber cap of the receiver and lifting the thin metal diaphragm from the face of two tiny magnets which were wound with fine silk wire.

"Regulation magnets," whispered Nichols, leaning over the detective's shoulder. "They're regulation except there's a hole drilled down between them. There must be a barrel all the way through the receiver."

"We'll see. Got those pliers, Delaney?"

The operative pa.s.sed up a pair. "Ah," chuckled the detective, uns.c.r.e.w.i.n.g the binding-posts and lifting off a hard rubber cap. "Ah, see here!"

Delaney rose and peered over the captain's shoulder straps. The two men watched Drew's nimble fingers trace out the mechanism of the electric pistol.

"It's simple!" declared the detective. "It's very simple and ingenious in construction. It's a crowning wonder to me that some one hasn't used this sort of device to carry out a wholesale slaughtering. Suppose they never thought of it."

Drew glanced at the silent mound under the Persian rug. "The wrong road," he whispered tersely. "He took the wrong road. He was a mechanical and electrical genius. He was a patent expert."

Delaney worked his brows up and down. "Shall I call Miss Stockbridge?"

he asked.

"I'll do it," Nichols said, turning and hurrying through the portieres.

He returned with Loris leaning upon his arm. Her eyes were glazed and tear-laden. She held a tiny, limp lace handkerchief between her trembling fingers.

"There's no danger," said Drew. "Come here, Miss Stockbridge," he added. "I want to show you what was all ready for you."

The detective raised the hard-rubber receiver. "Here we have the diaphragm," he said, pointing. "It's a round plate of soft iron. It's secured to the rubber by an insulated ring. It is the part you press up to your ear when you listen at a telephone. There's a small hole punched in this one. The same sized hole extends down through the center core, or magnet. This hole isn't rifled. It couldn't well be rifled save with special machinery. That's why the bullet found in Mr.

Stockbridge's brain was without longitudinal scorings. It was fired from a smooth-bored pistol."

"That's what you thought!" blurted Delaney with loyalty.

"I was at sea," said Drew. "Now," he continued, "we have a live cartridge at the opposite end of this core from the diaphragm. See it?"

Loris leaned over the little table.

"Right here!" The detective pointed. "That is a twenty-two cartridge with a cup.r.o.nickel bullet. See the cap? See how it is held from coming back by those tiny screws about the rim?"

Loris nodded and gathered up her straying hair.

"Now," continued Drew. "Now, this cartridge was exploded by the action of the human voice. Here's a tiny spiral of very slender platinum wire.

It must be number forty, at least. That's very fine! This spiral is in series with the winding about the magnets. The same current pulsated by the human voice which actuates the receiver diaphragm, also pa.s.sed through this spiral. Now," Drew paused. "Now," he added with rising voice, "here is a tiny charred piece of match-head, I guess. It was set in the coil. It flared when the wire became hot. The heat was sufficient to ignite the cap. See it!"

"I see it!" exclaimed Nichols.

"The action is simple," continued Drew. "A pulsation of the current which was formed by the action of the vibrating, transmitter diaphragm, also pulsated the fine wire before it went to the receiver magnets. The louder the voice into the transmitter the more current--measured in fractions of amperes--pa.s.sed through the spiral. It became sufficiently hot to flare the piece of match-head or whatever Cuthbert placed there.

This flare was communicated to the percussion cap, or fulminate of mercury, at the base of the cartridge. This exploded the powder charge, which in turn projected the cup.r.o.nickel bullet forward through the tube or the bore of the receiver and out through the thin, metal diaphragm, and----"