THE MYSTERY
OF THE
FIFTEEN SOUNDS

By Van Powell

The Goldsmith Publishing Company
CHICAGO

Copyright 1937 by
The Goldsmith Publishing Company
MANUFACTURED IN THE UNITED STATES OF AMERICA

FOREWORD

“No wonder I’m blue,” Roger told his father, “You’re packing to head a museum expedition into the heart of Borneo. You’ll have thrills.”

“Probably I will get my sort of excitement in plenty, Roger. It won’t be what you are always dreaming about—the ‘good old days’ of Pirates and Cowboys and Stage-Coach Bandits.”

“No,” Roger agreed, “the real thrills are all gone. But you can go on an expedition, instead of having school and——”

“There will be vacation time—baseball——”

“But I want real excitement. I’d like to be a Modern Pioneer. You are one, going off to Borneo for the museum just the way Columbus set out for Queen Isabella.”

His father looked up.

“You can be a Modern Pioneer. I will show you a House of Mystery, and once you step into its door you are in a land where there are more exciting activities packed into one day than you could get being a combination cow-hand, bad man, pirate and pony express rider. You may not be able to convoy an ox-team across a prairie, carry a squirrel gun and stand off scalping Sioux; but you will help battle against Pirate Fire, and Bad Man Erosion, and Bandit Microbe.”

“You mean—work in cousin Grover’s research lab?”

That was it, he found. And under the brilliant training of his older cousin, as he came to be the supply clerk and learned more about the work of the active place, Roger saw how truly his father had spoken.

There was fun, and mystery, and excitement, even in the work. Also, there was the feeling of being a Modern Pioneer, one who belonged to the band that had substituted electricity and wings for ox-wagon and candles, who gave the world instead of the pony rider carrying news, the radio and radio-telephone. Science was the Modern Pioneer.

Where their forefathers sought new borderlands, these modern way-showers explore the stratosphere. As their trail-blazing ancestors fought Indians and hardship and poor crops, these men battle against disease germs, and soil erosion, and eye-straining light and every other detriment to safer, happier existence.

As great as the feat of Columbus, Roger found the announcement that a cure had been found for a terrible disease.

On a par with Daniel Boone’s fame was the renown of the research worker who extended the range of compact radio receivers.

In such privately owned laboratories as that of his cousin, Grover Brown, and in those associated with universities and colleges and other institutions, the work of the Modern Pioneers went on.

They loved it, found adventure in it, and joy of achievement.

Not always was there the sort of mystery usually read about in detective stories; but when such problems did come up, Roger realized how the equipment of scientific research could be a useful aid to the clever deductive brain in solving the puzzle.

It is to show how much of adventure and thrill, excitement and romance can hide behind electrical transformers and tubes of germs, bags of sodium carbonate and humming motors that this experience of a boy in a scientific research laboratory is offered. Perhaps some boy, who has almost decided that the only “real” life involves guns and “rackets,” will be shown how the useful life of the fellow who fights for humanity and not against it brings more thrill and joy and contentment than any of the risky, falsely stimulating adventures that only lead to discredit, sorrow and punishment.

Van Powell

NOTE

Names used in this story are purely fictitious and if any name is like that of a real person it is coincidence and no libel or aspersion on character is intended or implied. However, every scientific device, process and theory herein is based on electrical, chemical and other data of developed apparatus and procedure or on theories so far perfected as to be acceptable to Science.

Contents

PAGE [Foreword] 9 CHAPTERS [1. “Them Mouses Is Extraverted!”] 17 [2. A Creeping Thing!] 23 [3. A “Sound” Clue] 29 [4. An Electrical Trap] 38 [5. What Electricity Could Not Catch] 44 [6. A Weird Story] 52 [7. Science to the Rescue] 60 [8. Basketball and Brains] 66 [9. The Voice in the Silence] 72 [10. A Defeat for Science!] 78 [11. A Puzzling Thump] 84 [12. Detective Roger] 90 [13. Scientist Roger] 97 [14. Captive Roger] 102 [15. In the Lamasery] 107 [16. The Image Speaks] 113 [17. Black Silence] 117 [18. A Letter Roger Had Not Sent] 121 [19. Disquieting Deductions] 127 [20. Ghost Voices] 131 [21. Tragedy!] 137 [22. What Happened to the Eye of Om] 143 [23. The Acid Test] 147 [24. An Impossible Camera “Shot”] 151 [25. Score One for the Mystery Wizard] 154 [26. Roger Lists His Clues] 159 [27. A “Thermal” Trick] 166 [28. The Fuse] 172 [29. A Surprising Capture] 176 [30. The Voiceless Warning] 184 [31. The Hidden Menace] 188 [32. Science Fights Craft] 191 [33. A New Suspicion] 195 [34. Tragedy Strikes Again] 201 [35. The Stalking Terror] 206 [36. A Law of Nature] 212 [37. Revelation!] 217 [38. The Vigil] 223 [39. The Ape and the Kangaroo] 227 [40. The Mystery Wizard’s Solution] 235 [41. Man and Beast] 241 [42. Closing Time] 246

Chapter 1
“THEM MOUSES IS EXTRAVERTED!”

Something was wrong at the laboratory! Ringing bells, long before dawn, awakened Roger Brown.

Dazed at first, he became alert as a strange, cold foreboding made him leap out of bed.

“Just the telephone,” his thirty year old cousin, head of the laboratory, called from his room beyond the adjoining bath. Roger, who was already on his way to the downstairs library of his cousin’s home, paused.

“No!” Well built and athletic, sharp-eyed, keen minded, a worthy student under his brilliant scientific cousin, Roger spoke earnestly, “It wasn’t just the protective beam system, or just the fire alarm, either. Grover, it was both!”

“Impossible! Why have they stopped ringing?” Tying his robe cord, the older cousin followed Roger. He knew that “Ear Detective’s” reputation for reading sounds, even if his own incisive reasoning made him feel that this time Roger had been too drowsy to live up to his nickname.

Just the same, he followed.

“As long as the beam was broken,” he insisted, “The bells ought to continue to ring. I think your fame as a sound interpreter is done.”

Roger did not try to defend himself.

“It was probably a wrong number on the telephone.” Grover was five steps behind his younger relative, “If you are so sure it was our alarm system, especially both bells, why aren’t you dressing to rush to the lab?”

“I’m getting down to be ready when Tip calls.”

Potiphar Potts, nicknamed Tip, was handy man at the scientific research plant. He slept there. In a moment Roger expected to have him call up to report the reason for the alarm.

“You will never hold your reputation now.” Grover turned at the library door as Roger, inside, stared, baffled, at the annunciator panel.

The reputation his cousin spoke about had come when a chemist, sent to them to help the laboratory develop a new series of dyes for a textile mill, had begun to “hear things.” Deaf, wearing an Amplivox, composed of a chest microphone, batteries and an ear piece, the man had been nearly crazed by a persecuting, accusing voice picked up, it seemed, by his device. Roger, by identifying an odd click he got in a makeshift imitation Amplivox set, gave Grover the clue through which a revengeful enemy who had sought to terrify the man had been discovered. As The Ear Detective, Roger, who was in charge of the laboratory stock-room, had really been the means of solving the mystery.

“I know I heard the laboratory bells,” Roger insisted.

“But the lights on our tell-tale are not lit.”

“I can’t help it. Both the fire alarm bell and the system that warns us if anybody enters——”

“But Potts has not called up, either. Go back to bed.”

Grover turned to leave the room. Roger, who was staying with his cousin while his own father headed an exploring expedition into Borneo for a museum, knew that his ears had not betrayed him.

His cousin, several years before, had secured capital with which to start a scientific research laboratory for the use of small companies unable to maintain equipment and an expensive staff.

Every form of research, electrical, chemical, industrial, and in one instance medical, had been successfully undertaken.

The “lab” prospered, and enjoyed a reputation for scientific and human thoroughness and dependability.

Priceless secrets, formulae, data and results were always in the laboratory, and its owner had devised seemingly perfect methods for safeguarding the secrets which rivals, or competing firms, might covet. A completed series of experiments to find a synthetic substitute for camphor gum, an industrial formula almost beyond price, was reposing in the safe on this early morning of Spring.

The safeguards comprised two:

There was a series of light-beams, interconnected with microphones and tiny speed cameras, at every possible entrance. Any broken beam, telling of wrongful entry, set off a laboratory bell in the room where Potts slept; and it also was wired to ring a bell at the owner’s home; and on a panel, numbered lights would show, by the one that glowed, which entrance had been used.

To protect the laboratory from fire, and warn of its existence, a bell of a higher tone with a thermostat connection in the laboratory, in each section, would give warning; and if the blaze was in the cellar, a green bulb would glow; if in the main floor, a red bulb, and for the upper section a blue bulb would be lit.

Naturally, Grover felt that his younger cousin had mistaken the sound that had awakened both.

Roger, still feeling his weird and unexplainable sense of hidden danger, picked up the telephone.

The laboratory, when he dialed repeatedly and waited long, did not respond. Tip, trusted, loyal, paid extra salary because he was counted on not to leave the mechanical devices to give the sole protection, should have answered his extension telephone.

“I tell you there is something wrong,” insisted Roger.

His cousin, partly convinced, taking on some of Roger’s concern, began to dress.

Just as he came down Roger knotted his tie.

In the car kept handy in the garage, they drove the several blocks to the two-story building.

Before they got near it, Grover put on speed.

Fire sirens and the scream of the warning signal on a police car made both cousins wonder what terrible situation they might face.

Had some one, entering the laboratory, set off the first alarm as fire broke out? Had Potts, fighting either fire or intruder, been rendered incapable of responding to their telephone call?

“Oh, I hope nothing has happened to Tip.”

Roger was very fond of the dull-witted, but dependable man, almost an Albino with his sandy hair and light eyes, who loved to use big words whether they fitted his idea or not, and who helped in the many mechanical, photographic and other activities involved in their work.

The car, racing forward, turned into the proper street and they saw fire apparatus gathering in front of the building. Roger, as the car slowed, leaped out, crouching and running to avoid being thrown down by the momentum.

“Don’t break in!” he shouted to firemen, “Our protective gas will prevent damage—and water would ruin our electrical things.”

The company captain paused as he saw, behind the youthful caller, the taller laboratory owner striding forward.

His men, with a battering ram, delayed.

The helmeted men, some with axes, others with scaling ladders, hose, or the rubber covers used by the emergency squad from the Fire Underwriters, paused.

“What-da-ya mean, nothing more won’t burn?” growled a policeman from the patrol car standing nearby.

His finger pointed toward the glass panel of the main door.

Roger, looking in, saw the curious orange glow and the weirdly bluish-violet splaying out across the office from the inner spaces.

“Who—what set off the flouroscope and the X-rays?” he gasped, while Grover reassured the gathered people.

Unobtrusively setting one foot well to the side on the top step, so that his toe, pressed forward, found the small protecting pin, he unlocked the door, careful to keep the knob turned toward the left, instead of in the natural hand-turn to the right.

That, Roger knew, cut out that particular light-beam system, so that they could enter without altering the present status of the tell-tale panel inside that would reveal where entry had been made, and by which magnetized plate the marauder would be held in trying to escape.

They rushed in. His first rush took Roger to the panel.

Not a bulb glowed! He stared, unable to accept the story it told—somebody had set off every light-beam-trip! That put out the lights.

Not one of the row connected-in with the magnetized plates was lit, either, and yet no living person should have walked or crept or climbed away through door, window, coal-chute or other exit without getting caught. But Roger did not pause. He ran to Tip’s room.

Tip, tied tightly to a bedpost, his lips taped shut, his eyes rolling as he sweated in his frantic effort to escape, saw him.

Roger first took the tape off as gently as haste allowed.

Just as soon as he was able to speak, Tip gasped:

“Tell Grover them mouses ain’t is.”

“Ain’t is?——”

He knew that Potts used queer phrases, trying to fit big words in, and this might be his way of leading up to some puzzling declaration.

“What happened? Stop being smart, and tell me!” ordered Roger.

“If mouses is here, you say they is here?”

“Well?——”

“They ain’t is.”

“Gone?” Roger stared, “The white rats. Gone?”

“They done extraverted.”

Roger had to study that out. He knew that the psychological word was used by analysts of human minds to indicate people whose outlook on life was normal, while introverts were shy, timid people who were afraid of life. “Extraverted” must mean that the animals had turned outward toward the world—run away, or escaped.

“But those white rats—Doctor Ryder’s—were in a cage with a trap door on top, and they’d been inoculated with cultures of a spinal disease,” cried Roger. “How do you know?”

“I was up lookin’ at ’em, and somethin’ with a hand like a ham hit me back of the ears, and when I come to, tied, them rats was evacuated. I was drug down here by a ape and tied. An’ there was somethin’ else I didn’t get a look at, behind the ape.”

Was the man crazed? It worried Roger.

But a call from Grover, upstairs, quickly told him that Potts had not been talking wildly.

“Roger,” called his cousin, “The white rats’ cage is empty!”

Chapter 2
A CREEPING THING!

It took Roger a moment only to realize the enormous danger that was behind the loss of those inoculated rats.

When Doctor Ryder had been allotted space in which to conduct his experiments to see if he could perfect a cure for a horribly deadly spinal affliction, he had decided to experiment, first, on animals.

Such experiments had been gotten under way the night before.

The rats, inoculated, were carriers of the deadly germs. If some ignorant person had taken them, and the public was not warned to be careful, anything might happen!

One of Grover’s constantly repeated axioms about laboratory work was:

“Do the first thing first!”

All life, the scientific student always had insisted, was like the chemical compounds they handled. No matter what the problem might be, no matter how it looked, it could be analyzed the way compounds would be analyzed, the elements could be isolated, and the base—the guide to the whole condition—could be known. Sodium, a metal, very unstable, combined with chlorine, a gas, turned into sodium chloride, and that was a salt—common table salt, in fact. Yet the restrainer used in photography, a dissolved salt, was sodium bromide, another gas and the metal, and to find out what a compound held, one had to separate all parts by test and find the base or original element.

But first, one must do the first thing—and in this situation Roger knew that the first thing was to get busy on the telephone.

White rats had been inoculated with dangerous germs. A bite from such an animal was ten times more terrible than that of a plain rat, poisonous though that would be. Therefore, if those inoculated animals were now missing, Grover, up where their cage had been, would know it already; but the public, exposed to possible contamination, must be warned.

Roger plugged in the upstairs telephone so that the policeman could reach his headquarters and start a widespread search of all cars on the roads, all suspicious people carrying sacks or other possible packages or cases that could hide the rats. The Health Department and news and radio agencies must be asked to broadcast public warnings. And the owner of the rats, Doctor Ryder, should be called.

Therefore, when Roger went upstairs, his report made his cousin nod approvingly. Roger had done all he could to avert danger if the rats had been taken ignorantly by some idiot who might let one or more escape and spread disease germs.

With his story told, Potts was busy doing what Grover had ordered as one way to secure clues: a motion picture camera using non-flam film, flashbulbs of the latest type, tripod for time exposing, and both wide-angle and micrometric lenses, to give large views of big spaces or vastly magnified details of practically invisible things, formed the kit that the handy man worked with.

Because he had used his wit Grover had no orders for Roger as the firemen, police and officers departed.

Nothing could be done until Potts developed his “takes” so they could be run in the laboratory screening-room.

Grover, in his small, private “thinking den,” would want to be left to think out and separate all the mysteries, so that he could get to the heart of the affair and thus decide what to do about it.

Alone, wide-awake, with the dawn just beginning to lighten the skylight in the roof over his stock-room, Roger stood thinking.

He knew that if the small, partitioned space set aside for Doctor Ryder had held clues, Grover would have told him.

The germs supposed to have been injected into rats the night before could not have produced much effect that past night. The doctor had not felt that he had to observe, personally, as he would have done later.

Instead, automatic “observers” had been set up.

Inside the empty cage, a dictagraph microphone showed, fixed to the glass inside the cage top. That, Roger knew, led to a device like the seismograph which registers earthquake tremors. Its purpose was to show, by the vibration of a pen across a moving tape, when the rats developed any unusual excitement or stress, which was not expected but was provided for in that way.

A camera of the moving picture type, but set to snap one take at minute intervals, would check also; and if the seismograph got to zig-zagging sharply, it would make contact on one side with a relay, and throw on the “continuous” mechanism of the marvelous camera.

To discover by calculating how much of the tape had been unreeled when something had stopped it, was easy; and in that way Roger knew the time that the mechanism had stopped, although he did not dare fix that as the time the rats had vanished, because the tape had started at five in the afternoon, and had unreeled to the point to show that it had stopped at four in the morning; but the alarm had not sounded until half an hour or so later.

The tape showed excited swerves of the recording stylus, but not apparently enough to start the continuous takes, because Grover had left the magazine as it was until Potts should be ready to develop all prints at one time.

With his snapshots and time exposures of wide-angles of windows, doors, floors, air-conditioning intake, exhaust, cellar openings and floors, and his micrometric detail close-ups of parts of all these, Potts went to the dark-room adjoining Roger’s stock-room. The film he had taken would fill all tanks, so he left the other till later.

The authorities had been warned; and nothing more could be done.

Roger, as the sun rose, telephoned for light breakfast to be sent from a nearby restaurant, taking Potts his share in the dark-room.

As he ate, Roger tried to bring some sense into the baffling set of conditions:

The white rats, in their cage, with the observation apparatus and chart with notations, should have been recognized by anybody who could see and who could read, as dangerous to handle, much more to remove.

With the protecting system set, it should have been impossible to enter, at all, and more impossible to get out.

Yet the rats had not by any magic been evaporated into thin air.

Furthermore, Roger mused, why had the fluoroscope and X-ray machinery been put into operation?

The entire situation seemed to be too bizarre to be true: more than all the rest, the mad story of Potts that he had felt a hand as “big as a ham,” hit him before he had lost his senses!

Nothing fitted anything else.

Doctor Ryder, arriving, was as much a contrast to cold, unexcited Grover as could be imagined. He sputtered his fears for the public, his dismay that this should have brought discredit on the laboratory that had been known to safeguard its precious data.

Roger, watching the pudgy, stout little germ experimenter who excitedly mixed wild theories with wilder plans of procedure, thought to himself that if anybody or anything would upset his cousin, the man’s emotional excitement would be the thing.

Grover was not stirred out of his quiet manner.

The staff began to arrive. They had all seen in newspapers or had heard by radio the warnings and the brief story of the lost rats.

Mr. Millman, the electrical engineer, asked immediately of Dr. Ryder: “Have you any enemies?”

The experimenter thought that he might have antagonists among the scientists who disagreed with his theories; but they would not be men who would endanger the public for so small a revenge as could come from criticism of his laxness in not watching his experiment more closely.

Mr. Ellison, the laboratory’s electrical research specialist who worked with Mr. Millman, agreed; and so did the bio-chemist, Mr. Zendt; the analytical chemist, Mr. Hope, and Grover.

They were discussing the many contradictory and unexplainable points when Potts called, from the darkroom:

“Hi, Rog’—come quick!”

As soon as his eyes were accustomed to the dull rosy glow after he passed the light-trap, Roger saw Tip clipping non-flam film positives to drying drums.

“What have you got, Tip?”

“Look!”

Potts snapped a strip in place in a vision tunnel: Roger applied his eye to the lens, and saw, enlarged on the viewing-plate, what appeared to be the edge of a cellar step. With side-lighting, magnified ridges and depressions in dust looked like a range of hills and vales.

“It was a snake!”

“A—did you say ‘snake’?” Roger gasped, “How do you get that?”

Potts changed films under Roger’s gaze; an enlarged wide-angle of several steps was before his eyes, and the snake-slide of some body that had dragged across just the step-edges, and had made no track of hand or foot on the level of the steps showed!

“It certainly looks like something that creeps, Tip.”

“Well, a snake creeps. A snake! What else?”

Chapter 3
A “SOUND” CLUE

Without waiting for the gelatin to harden, Roger summoned the staff and his cousin to the screening room. As soon as they had set their wrist watches with the observatory time signals, a routine part of the staff’s accuracy, they joined him.

He had the tender emulsion-covered celluloid threaded from the top magazine through film gate and take-up sprockets down to the lower magazine of the projector. In the small, compact theatre, with its platform for lecture and demonstration procedure, its large screen, easy chairs, loud speakers and apparatus, he showed Grover and the men what caused him to agree with Tip.

“It almost has to be a snake,” Roger declared.

No other than a creeping thing could drag over a step edge. Four footed creatures, he explained, did not disturb dust at the point indicated in close-up and wide-angle pictures, greatly enlarged by the projector.

The chief electrical specialist, Mr. Ellison, agreed. “It ends the mystery. A snake ate the rats.”

“Then there won’t be any disease epidemic,” Doctor Ryder was much relieved, “It will crawl somewhere and the germs may destroy the reptile.” To this Mr. Millman, electrical engineer; Mr. Zendt, bio-chemist; Mr. Hope, their analyst, and others, agreed.

Roger saw that his cousin reserved opinion. But routine had to go forward, and the staff men separated. Zendt went to resume experiments in the search for a dye of a certain desired shade and quality: the two electrical men were busy developing means to find a better way to insulate high-tension cable for carrying electricity from generators to distributing stations in small communities; the others had equally absorbing work in progress.

Grover, busy examining each picture projected and held on the screen without danger of the “cold” light igniting the protected film, gave Roger a dozen cellar views around the coal-chute to enlarge.

“Make ten-by-twelve bromide enlargement prints,” he ordered.

Roger, although it seemed impossible that anyone could have moved the stiff rusted bolt inside the trapdoor of the coal chute, a trap that lifted up and out onto the street, said no word of objection.

He felt that Grover would find nothing in the enlargements.

Expertly he adjusted paper on the camera-stand, extended the bellows to secure most perfect focus, made his exposures, developed, and fixed the large prints, and took them to his cousin’s own den.

“As I expected—nothing!” he reported.

“No abrasions of the bolt, or edge of the trap?”

“You mean, where someone inserted a ‘jimmy’ to shove back the bolt?”

Grover nodded.

“Not a thing shows.” Roger asserted. His cousin did not accept his statement; but his disappointed eyes told Roger that the examination he had made during developing work had been accurate, thorough, and had led to a correct decision.

They were at a standstill. Calls to the zoo, brought from its curator the declaration that no snake was absent from its cage, that no one of his keepers had tried to “train” snakes—as the laboratory head had half-laughingly suggested.

As he left the screening room, Roger met Potts.

“Tip,” he hailed, “Did you get anything on the ‘sound’ film in the one-snap-a-minute camera?”

“The one that took pictures of them mouses?”

“The one by the rats’ cage—yes.”

“You know about sound, Rog’. It ain’t just a lot of single pictures.” Potts wanted to air his knowledge. “Sound is a maintained concession of peaks an’ valleys on the sound track.”

“You always will use a .44 caliber word when a BB. size would hit what you aim at and not blow your idea to bits, Tip. You mean that sound is a ‘sustained succession’—I know that. And single frames, if they showed any sound impression at all, would give little pops.”

“So I didn’t bother.”

“But, Tip! There was a lot of wild zig-zag marking on the tape in the seismograph-like recorder; and it seemed as though the ‘continuous’ taking lever had been shifted before he—it—whatever was there, stopped the whole business by breaking off the wiring.”

“We can try.”

When they had developed the negative, made a print and fixed and washed it, Roger threaded the fifteen frames of continuous shots in place and projected with the speakers cut in.

Then he rushed to get Grover. The staff too!

He had a clue.

As nearly as he could have described the brief sound made and amplified with transformer-coupled, matched metal audio tubes of the most perfect type giving the speakers power, they had picked up a sound of hot grease sputtering, hissing and clicking, as it does if sausage is fried rapidly.

“Come on, Ear Detective,” chaffed Mr. Millman, “Who was frizzling sausages on the cage full of inoculated rats, so that the mike inside picked it up and took it on to the sound film?”

“That’s not sausage frying,” exclaimed the biochemist, “Someone had steam up and the mike picked up the sound the radiator valve made as air was expelled and steam arrived to close it spasmodically.”

“A microphone, inside of a glass cage top?” mocked Mr. Ellison. “How could a valve on a radiator across the room make all that noise?”

“Let the Ear Detective explain it,” urged Mr. Hope.

They all turned to Roger. He shook his head.

“It does sound most like the snick-snap, and sizzle, of sausage,” he admitted, “But——”

“It’s a snake, I say,” Potts defended his theory; “a snake, with hissing and his scales rattling on the glass when he was crawling up to dig his head in and grab breakfast.”

“What’s your idea, Grover?” asked Mr. Hope.

“Sounds as much like a snake as anything I can imagine, Sam.”

“So say I,” agreed Mr. Ellison.

“Are we right, interpreter?” Potts got the correct word, for once.

Roger hesitated. Not that he cared if he lost his reputation as a young person able to read correctly what his sensitive ears caught; Roger was not vain or self-satisfied. He was not the sort to make a statement just to hold up his reputation.

In some ways the sound might be such as a snake, with its hide striking or rubbing, as it hissed, could make; but, again, a lizard might make that sound—or a dog, scratching on a window.

He stood up, excited for the moment.

“Claws on glass!”

His sharp cry died into silence. They all considered it.

“A snake ain’t got pedicular exuberances,” objected Potts.

“Pedal protuberances, eh, Tip?” chuckled Mr. Hope, “What do you say, Grover?”

As Roger looked toward his cousin he saw what surprised him most of all that had so far happened.

Never in his stay at home or laboratory, intimately close to the scientifically brilliant, but poised, cousin, had Roger seen him lose his calm.

Now, Grover stood up, and in his eyes was the same sort of light of satisfaction and triumph that a boy would show when he had successfully smuggled in and hidden mother’s birthday present.

“Roger is absolutely right!”

“Claws on glass? A big dog?” asked Mr. Zendt.

“Remember the cellar step clue.”

“A lizard?” Mr. Ellison suggested.

“Remember Tip’s statement about how he was knocked senseless.”

“Oh—a man with a—a what?” Mr. Millman was not so confident of his deductive ability. He paused.

“I will leave you to work it out,” Grover beckoned to Roger; “I must run out to the zoo.” He was as eager and elated as a boy with a new football.

He beckoned to Roger who followed as his cousin got his hat.

“I want you to go to all the newspaper offices. Take a taxi. Get back issues for the past two weeks, maybe you’d better get them for three weeks back.”

“You know?——”

“I have two theories. I want to make sure which is right.”

“Do you really think I got the right meaning out of the hisses?”

“Precisely the correct meaning.”

“But it doesn’t tell me anything, cousin Grover.”

“Use my formula. Dig past appearances that can be falsified, to the truth. Marshal your facts, test each one, eliminate the impossible and what you have left is the truth.”

Telephoning to summon a taxi for Roger, the laboratory head was busy for a moment. Roger tried to employ the method just named.

Youth, inexperience in doing such consecutive and eliminative thinking, he knew, hampered him. With a mind trained, through solving chemical, electrical and other industrial experimental difficulties, Grover’s clever mind had skipped many of the links that Roger, slowly, had to take up and examine.

He was in the taxi, with bundles of back issues of the city papers, on his way back, and still his mind was a maze of unfitted details.

In the office, combing the papers for notes about snakes, or any other escaped reptile—he had to keep in mind that trail on the edge of the steps alone!—he got nowhere.

No news showed up about lost, stolen or escaped animals or any form of brute or reptile.

Grover, he saw, had returned, and was not joyful.

“One theory went to smash,” he said, “I verified your sound—claws on glass was the right deduction. But—that doesn’t bring what I want.”

“What do you want?” asked Roger, eagerly.

“To capture the culprit.”

“Won’t the police?——”

“We have no justification for calling them in. Nothing has been stolen. Nothing has been harmed.”

“The rats——the menace to the public!”

“Roger, you haven’t studied those films Potts took.”

Roger got them at once, projected, one at a time, examining the screen images carefully. The cellar views, only proving that some object left no other trace of progress than scraped dust on step-edges, he considered and discarded.

Those taken by windows, doors, intakes and outlets of the air-conditioning, and gas-exhausting roof, cellar and wall orifices gave no revealing clues.

When he got to the wide-angles of the lower floor and stairway, and found no reward for his long scrutiny, Roger was baffled.

Only the micrometric enlarged snaps and one time-exposure near the X-ray devices remained. He considered them ruefully. They gave no foreground evidence to help him.

Roger, with defeat creeping over his feelings, was about to give up.

He was fair, he told himself, when it came to interpreting sounds, but at the more important quality of being able to connect the clue with everything else, he was “stumped.”

What could those enlarged views hide from him?

The walls, with racks of test-tubes, some containing chemical solutions, others holding cultures of various forms of growth that Mr. Zendt had accumulated or was studying, told him——

He stared, bent closer, climbed up on a chair close to the screen!

After two minutes of close scrutiny, he jumped to the floor, and raced to find Grover.

“Just by chance, in taking the micro-lens pictures,” he gasped out, “Tip got in some of the test-tubes. Is that what you saw?”

Grover, smiling, agreed. “What did it tell you?”

“I arranged those racks yesterday. I have got a good memory.”

“I knew both those facts,” Grover admitted, “and I, too, helped in revising our arrangement of the racks. Go on!”

“The tubes that held the culture of the spinal disease germs—so dangerous that they had been delivered, personally, by the medical center bacteriologist, had blue labels!”

“You are ‘warm’ as the hide-and-seek game puts it.”

“I saw Doctor Ryder take them up, in his surgeon’s clothes to prevent infection.”

“So did I.” Grover acknowledged the fact.

“He actually took two tubes that must have had the right labels because he would have seen what they were marked.”

“Labels can be soaked off and transposed from one tube to another, Roger.”

“I think that happened. He took them, went up, and we both saw him use the hypodermic needle.”

“But—” Roger could hardly restrain his thrill at having made as clever a discovery as the coming one:

“Those two tubes—full!—are in back of others, right now. Not the two empty ones he incinerated to be sure the germs were all destroyed.”

“They are? How did you discover it?”

Roger told him: “Our chemical labels that are a green, photograph a darkish gray; and our culture labels, that are a buff, photograph lighter, but still grayer than white paper. The poisons are labeled red and come out in a picture almost black.

“But blue except very dark shades, will photograph nearly white! And those two labels, hidden in a dark corner, show up in the picture where they might not be noticed in the rack.”

“Can you go further and say why no culture was allowed to be given, although the inoculator evidently thought his serum was genuine?”

“Whoever was going to take the rats, did not want them to be dangerous to him.”

“Very nicely argued out, Roger,” his cousin complimented him. “Now, we must find a way to draw that criminal who trains animals to do his work, into the open where police can get him.”

Chapter 4
AN ELECTRICAL TRAP

Startling though Grover’s statement that a man trained animals to be criminals was, it gave Roger the one link to build what he knew into a chain.

Trained animals! That fitted in with claws on glass and made the rest of the puzzle fall into place.

To Roger, it seemed clear that a clever animal trainer could teach his beasts to obey criminally intended orders just as well as make them do the ordinary tricks.

What animal, he mused, would fit the conditions?

A monkey came to mind as the logical sort.

First of all, it was the one animal able to climb down a rope from the skylight on the roof, which it could have reached by being taken up the fire-escape on a candy factory next door, one story higher than Grover’s research laboratory.

Coming down in that fashion, it could have been made to do a trick taught for the purpose—take the white rats, put them in a sack, and fix it to the rope—or the sack could already be at the end of the rope. Then, unaware that it had set off an alarm, it could have wandered about, doing such tricks as getting into the light beams, pulling the switch to “on” for the X-ray and the other electrical devices.

Such an ape, too, with its master joining it during the time it wandered about, could have invaded Tip’s room, striking him with a huge paw, because it would be an ape; no smaller monkey could have reached down into the rats’ cage.

“How will you trap him?” Roger asked.

When his cousin outlined his plan, Roger was animated.

“It might work,” he exclaimed, “He will turn out to be the one who brought the white rats. They were trained, too, maybe.”

“I wondered that you did not see why I bought back issues of the newspapers,” Grover told him, “I had one idea that the thing might have been done by some zoo keeper; but the more possible notion was that some vaudeville act had trained animals. Now we do not need to comb through the advertisements of the theatre section. We know, by logical deduction, that we would find it.”

Roger, and Potts, carrying out instructions about which they said nothing to any member of the staff, assembled a mass of materials, apparatus and paraphernalia.

There were microphones; and they employed the laboratory’s device for producing infra-red rays, as well as a number of small cameras for taking motion pictures which Potts secured; to each one they applied a shutter-trip suggested by Grover, that would operate when a light-beam of the infra-red variety might be unknowingly broken by an intruder.

Other parts, and wiring by the yard, they connected up.

“But I don’t understand it,” Potts argued as they worked. “It’s all right to say a monkey climbed in through the skylight way; but how does that fit the snake-trail up the stairway?”

“I asked about that,” Roger told him, “Cousin Grover was more in a joking humor than I ever saw him, and he said I’d done so well, he would leave that for me to work out, too.”

“Did you?”

“I think so, Tip. How’s this? Monkey comes in. No alarm on the skylight, because the magnetic plate under it would be ‘on’ all night and would have caught anybody—anything but a monkey able to jump at a command while it swung clear—or the man above swung it.”

“So far, so good.” Potts waited expectantly.

“The ape wandered around, until it heard a call it recognized from outside, on the street. It was trained to open bolts, and the only other bolt that wouldn’t have a camera equipment and electric plate was our coal chute, that had the Chief stumped how to fix it.”

“And why would he have to go down there?”

“To let in his mate—another beast.”

“And what was it?”

“Well, what could leave a snake trail?”

“A boa-constrictor, or one of them bushmasters out of Australia?”

“What else—out of Australia?”

Potiphar stared, thinking hard.

“I don’t know.”

“Something that hops, and balances with its tail.”

“A—you mean a—kangaroo?”

Roger chuckled, nodding.

“But why did they go to all that trouble, when a man could of swarmed down a rope, and got the rats?”

“If he’d got caught—not knowing everything about the inside of our lab, maybe,” Roger responded, “He’d go to jail. But if we got a kangaroo, or an ape, the animal trainer could know it and have an ad. in next day’s papers, get back his animal that couldn’t tell what it was there for, and——”

“Well, what was it here for? What made all that compulsatory?”

“The motive made it compulsory, Tip.”

“You didn’t tell me about any motive. Or how all this wire and stuff will catch anything when we don’t know anything will come tonight, like you hint at.”

“The motive, Cousin Grover thinks, is to get into our safe, for our data and formula for synthetic camphor.”