Carl & Jerry: Ultrasonic Sound Waves
July 1955 Popular Electronics

July 1955 Popular Electronics Table of Contents Wax nostalgic about and learn from the history of early electronics. See articles from Popular Electronics, published October 1954 - April 1985. All copyrights are hereby acknowledged.

Aside from the storyline, one notable aspect of this installment of Carl & Jerry is one of the illustrations used in it. Jeff Duntemann (K7JPD), himself a sci-fi and technical book author, wrote a piece on the evolution of John T. Frye's Carl & Jerry series in Popular Electronics, and in it he commented on the changes in drawing styles and character appearances over the many years that Frye inked his illustrations. I read Duntemann's article a while ago, but remembered the picture of Norma and Carl's dog Roscoe when I saw it again just now. The format obviously departs from the vast majority of Frye's typical works due to its distinctly cartoonish look. As for the plot of the story - it involves an attempt to shake the wings off mosquitoes.

Carl & Jerry: Ultrasonic Sound Waves

By John T Frye

The shadowy coolness of Jerry's basement lab was a welcome relief from the shimmering heat outside. As Carl came in, he saw Jerry's rotund figure perched on top of a stool at the workbench, on which rested a delicate horn pan balance with a one-milligram weight in one of its pans. With a pair of tweezers, Jerry was carefully transferring some minute objects from a fruit jar lid to the other pan.

With a pair of tweezers, he carefully transferred the mosquitoes to the pan ...

"Looks like you're really up to big business today," Carl observed. "What're you weighing, peach fuzz?"

"Nope, ... mosquito cadavers," Jerry said, as his round face wreathed itself into an enigmatic smile.

Carl moved to the bench and peered down through his horn-rimmed glasses at the jar lid. Sure enough, in it were several rather badly mauled mosquito carcasses.

"Why?" Carl demanded.

"We-l-l-l," Jerry said hesitatingly, "It's a rather long story-"

"Never mind the buildup," Carl interrupted. "You know you're dying to tell me; so give."

"It all started a couple of nights ago.

Looking out my bedroom window, I saw Norma, the girl next door, sitting on her porch swing, blubbering and crying away. Thinking that maybe she had locked herself out of the house or something, I went down to see what was wrong.

"It developed that a character by the name of Melvin Akers, who works at the bank, has her 'snowed.' For the life of me, I can't see why, for this Melvin guy is the sort even nature hates. He's allergic to anything that grows. He breaks out in a rash if anyone even mentions onions or radishes. She swears he can get ivy poisoning just from seeing the word 'ivy' in print.

"Even so, she has her mind dead set on marrying the creep; and that night she thought she practically had the job done. Melvin was in a rare mood - for him - with nothing to take his attention off her; and he had even made a couple of cracks about how pretty her hair looked in the moonlight.

"They sat down in the porch swing, and she started rehearsing mentally just how she was going to say 'I will' to his proposal. Then, all of a sudden, Melvin began slapping at his face and ankles, and suddenly stood up and said he had to leave. He's one of those people mosquitoes love to bite, and the bites swell up on him. So, he had to get home quickly and use some special ointment on them.

"That was why she was crying. She said she'd pinned her hopes on this moonlit porch swing setting all spring; and now that it had failed, she just knew Melvin would never propose."

"Why doesn't she try citronella?" Carl asked.

"I thought of that, too, but she says the odor clashes with her Sweet Surrender perfume, in which she has invested no small sum and which she is sure plays a big part in giving old Melvin the business. I told her I'd try to see if I couldn't think of something to help her."

"How come you're so eager to play Cupid?" Carl asked suspiciously; "although I must admit you've got the figure for it. You going soft on this gal, too?"

"You got rocks in your head?" Jerry demanded witheringly. "She's practically an old woman. I'll bet she's 22 or 23 if she's a day. It's just that I don't like having someone bawling under my window when I'm trying to sleep. And then, her problem appeals to my scientific curiosity."

"How about Melvin? Don't you think it's playing it kind of low down to help trap a fellow man?"

"That bothered me a little until I happened to remember he was the local joker who wrote to the FCC and said he was sure we radio amateurs were interfering with his TV reception. All his trouble was being caused by an old-fashioned carbon filament light bulb in his basement. Some of those old bulbs act like miniature TV transmitters and cause interference to crawl up and down the picture."

"He deserves to get married!" was Carl's prompt, harsh judgment; "but how are you going to help with the mosquito situation?"

"I got an idea from something I read in Radio & TV News two or three years ago. You know sound waves can exert severe stress on objects that are resonant to the frequency of the sound. Remember how some opera singers can shatter a wine glass just by holding the right high note? Well, I think I can produce an ultrasonic sound wave at a frequency which will vibrate a mosquito violently and destroy him without people being able to hear the sound.

"Yesterday I borrowed a high-power movie sound system tweeter speaker from a projectionist friend of mind and hooked it across the output of my hi-fi amplifier. This amplifier has frequency response clear up to 100,000 cycles; so when I ran my audio signal generator into the front end of the amplifier, I got considerable power output from the speaker above the range of hearing. To check this, I suspended a tiny pith ball on a light thread in the path of the narrow cone of sound put out by the speaker and then varied the frequency of the signal generator. At certain ultrasonic frequencies, the ball was jerked back and forth so violently by the inaudible sound waves that it looked blurred. I'm sure that if I can hit just the right frequency I can exert several G's of stress on a mosquito and shake him loose from his wings!"

"Why are you weighing the mosquitoes?"

" ... To get the average weight to use in the acceleration graphs and formulas for vibratory motion that I found down at the library. They're pretty hard to use, but if I do it right I should be able to figure out just the right frequency to apply maximum stress to a single mosquito."

As he talked, Jerry finally got the scales to show a satisfactory balance; and then he carefully counted the dead mosquitoes in the pan. Next he reached for his battered slide rule, made a few calculations, and jotted down some figures on a pad.

"We-l-l," he finally said hesitatingly, "if I've not slipped somewhere, it looks as though a frequency of about 19,000 cycles ought to do it. Tonight I'll run that frequency into the amplifier and direct the cone of sound from the tweeter speaker right at Norma's porch swing from my upstairs window. She says she'll maneuver Melvin into position there promptly at 10:30 if she has to chloroform him. I'll keep the mosquitoes at bay with my supersonic ray until Norma and her Sweet Surrender perfume have done their dirty work."

"You playing an electronic Cupid is something I've got to see," Carl announced. "Reserve me a seat up in your room tonight. I'll be over right after that 9:30 shoot-em-up TV program."

He was as good as his word, and the two boys squatted on the floor by the window of the hot, darkened bedroom for almost an hour before they heard the picket gate of the house next door click open and shut, and caught sight of two figures walking onto the vine-hung front porch. Jerry already had the amplifier warmed up; and as he heard the rhythmic squeaking of the porch swing chains, he flipped on the oscillator that had been preset to the ultrasonic frequency. The shift in the fluorescent blue glow on the glass envelopes of the amplifier output tubes indicated that they were delivering power. No sound was heard from the speaker, however, and there was no halt in the rhythmic squeaking of the swing chains.

"Well, at least Melvin can't hear the sound," Jerry whispered hoarsely as he stared down at the darkened porch. Just as he said this, there was an anguished howl from below, and a frantic ball of white erupted from beneath the porch and ran crazily about the moonlit yard.

"Holy cow!" Carl gasped, "it's Bosco!

What's the matter with him?"

Before Jerry could answer, Melvin's trembling voice floated up to them: "It's a mad dog!" he shrieked. Then he burst from the shadow of the porch, and with two giant steps reached the picket fence and vaulted nimbly over it. He alighted on the sidewalk running, and as his staccato footsteps died away in the distance, Jerry reached over and switched off the oscillator. Instantly Bosco's howling stopped.

"Bosco certainly fouled that up," Jerry said sadly. "Dogs can hear sounds too high-pitched for human beings, and that high frequency note must have been pretty painful to poor Bosco's ears.

The two boys went downstairs and across the yard. To their astonishment, they heard the sound of almost hysterical laughter coming from the porch, and then Norma ran down the steps, threw her arms about them, and kissed each squirming boy soundly on the cheek.

Norma ran down the porch steps as Bosco pawed gingerly at his ears ...

"I'll never, never forget how funny Melvin looked as he went over that fence," she finally managed to gasp. "And I want you boys to know I'll never forget what you've done for me. I guess I felt sorry for Melvin because he seemed to have so much trouble, and I foolishly thought I was in love with him; but I certainly couldn't love anyone who would run off and leave me alone with a mad dog ... I don't know how you did it, but you're wonderful!"

As she said this, she stooped down and picked up Bosco, still pawing gingerly at his ears, and gave the dog a big hug; then she went into the house, giggling happily.

"Women!" Carl said disgustedly, as he rubbed the lipstick print off his cheek vigorously with the back of his hand.

"Check," Jerry agreed. "I suppose we may as well go to bed now, but I'm coming over the first thing in the morning to see if there are any wingless mosquito fuselages lying around under that swing."

Carl took a couple of steps and then turned around. "Hey, Jer," he said thoughtfully, "I wonder if you'd promise me something."

"Sure thing. What is it?"

"Well, if I should ever become so weak-minded as to think I want a girlfriend, just let me manage my love life all by myself, will you? Please don't try to help me !"

Posted June 4, 2014