Carl & Jerry: Sonar Sleuthing, August 1963 Popular Electronics

August 1963 Popular Electronics

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.

In this August 1963 adventure, teenage techno-investigators Carl and Jerry use their home-brew sonar device to help the local sheriff nab a couple bank robbers. The 'Hydro Probe' mentioned in the article was a real product manufactured by the Raymond Development Company of Watertown, Massachusetts (no longer in business). Enjoy.

Carl & Jerry: Sonar Sleuthing

By John T. Frye W9EGV

Jerry inched forward slowly, keeping his depth ... suddenly the end of the sonar unit bumped into a large object in the water.

Up periscope!" Jerry called to Carl, and the latter released the large cylindrical object he had been holding on the bottom of Jerry's full bathtub and watched it slowly rise to the surface.

The youths were checking out their latest "invention," a hand-held portable sonar unit for use in scuba diving. Actually it was just a crude copy of the Hydro Probe manufactured and sold by the Raymond Development Company of Watertown, Massachusetts. While the unit the boys had made was much larger and clumsier than the commercial version, it operated on the same general principle.

They had simply installed inside a large paint bucket a flashing-light type transistorized depth-finder. The depth-finder was the same kind they had used at Parvoo University to locate a metal plaque at the bottom of the river. A five-inch diameter circle had been cut from the center of the airtight lid, and a heavy sheet of Plexiglas had been cemented over this opening so that the depth-finder dial mounted just behind it could be seen. The transducer had been fastened to the outside bottom of the can, and the cable from it led inside through a waterproof seal.

Finally, the on-off/sensitivity control was connected through a speed-reducing gear train to a tiny permanent magnet reversible electric motor. The motor, in turn, was controlled by a spring-loaded, normally-off, double-pole, double-throw toggle switch mounted on the side of the paint bucket. An unpierced nursing bottle nipple, with its rim cemented to the bucket, slipped over the bat handle of this switch, and permitted control of the sonar device inside its waterproof seal.

"That does it," Carl said, lifting the dripping unit from the bathtub and holding it in front of his face by means of the two strong handles soldered to the sides of the can. "It barely floats, so it should be easy to maneuver under water, and it doesn't leak a drop. Let's take it to the old quarry and try it out."

"O. K.," Jerry agreed. "You load the scuba gear in the car while I dry this thing off. Mom'll kill us if we drip water on her floors."

A half hour later the boys left the highway and traveled a short distance along a side road until they reached the abandoned quarry. They were just getting out of their car when they were surprised by the voice of the county sheriff.

"Over here, fellows," he called, emerging from the undergrowth. They could see the sheriff's car parked behind some bushes growing between the road and the edge of the steep-sided quarry.

He was an old friend, and Carl did not hesitate to ask, "Hey, what are you hiding from?"

"Remember that branch-bank holdup at the shopping center a little over a year ago?" he asked. "The two men we think did the job ran through a roadblock and came out on the highway with the state troopers on their tail. They took off on this road and lost the state police for a few minutes - about fifteen. The police closed in from both ends of this short road and took them not a quarter of a mile from here, but none of the bank loot was on them."

"We searched every inch of the road and a hundred yards either side," the sheriff continued. "The prosecutor didn't have enough on them to try them for the bank job, but they both did a year in the pen for possession of a stolen car. Their sentences were up last week, and I'm staked out here on a hunch those two birds stashed the dough away, and will try to come back for it."

"Maybe they threw the money in the quarry," Carl suggested.

"We thought of that, and state police divers spent two whole days exploring the bottom, yard by yard. They had to do most of their searching by touch because working of the sand pits along the little creek feeding into the quarry keeps the water riled up so you can't see more than a foot or so in front of you. The divers found old tires, empty beer cans, rolls of rusty fence wire, baby buggies - everything but money. But what devilment are you two ..."

Before he could finish his question, an emergency call tripped the squelch of the radio installed in his car. The city police had just received a telephoned tip that a supermarket on the other side of town was to be held up, and the dispatcher relayed the information along with the message that all mobile units in the county were ordered to converge on the spot.

"Stick around, I'll be back," the sheriff said as he headed for the highway.

Carl and Jerry walked down a slope to the edge of the quarry. Across and to the right, the sheer walls of the large pit went almost straight down to the surface of the muddy water some thirty feet below. Where they were standing, a thick curtain of vines grew over the edge and cascaded down until the vine ends trailed in the water. Over to the left, however, a steep path zigzagged down to a narrow ledge running around the quarry a foot or so above the water.

They lugged their gear down this path, and Carl helped Jerry put on the scuba outfit. In practically every other physical endeavor, Carl was easily Jerry's superior; but in swimming, the chubby youth was as much at home in the water as an otter. "Blubber floats better than muscle." was Carl's succinct and disparaging explanation.

With the diving equipment in place and checked out, Jerry picked up the portable sonar and slid beneath the murky water. Going down a few feet, he worked the rubber-covered switch handle to turn the unit on and adjust the sensitivity.

The two glowing spots of neon light on the dial of the depth-sounder were easily seen when the Plexiglas disk was held close to his eyes, and he was delighted to find the crude affair working exactly as anticipated. Not only did it indicate how far the bottom was beneath him, but the stone walls of the quarry also returned sharp echoes to indicate their distance from his location. Moreover, when he turned on his back and pointed the instrument straight up, an echo was returned from the air-water interface that indicated how deep he was swimming.

He played with the instrument for several minutes, trying it out at different depths and "swimming blind" with only the sonar ranging indication of the instrument to tell him how deep he was swimming and to warn him when he approached the bottom or sides of the quarry. While he was swimming some fifteen feet below the surface toward the vine-covered wall of the pit, the distance-indicating spot of light suddenly jumped counterclockwise from the ten-foot to the five-foot position. Swinging the instrument slightly to either side or up or down returned the spot of light to the more distant indication.

Keeping his depth, Jerry inched slowly forward until the front end of his paint bucket bumped into something suspended in the water. Inspection with his hands revealed it was a large metal container of the kind pressure-gun grease is kept in at a filling station. A thin wire led straight up from the bail, and Jerry followed this upward with his hands until he came to the surface.

He discovered he was behind the screen of vines and that the thin strand of steel piano wire ran up through these vines to the top of the quarry. He was about to call to Carl, whom he could see through the leaves, when he was stopped by the sound of a man's voice above him yelling at Carl.

"Just stay where you are and keep your mouth shut, buddy, and you won't get hurt. My friend, Chauncey, and I just want to pick up something we left here a while back. When we get it, we'll go our way and you can go yours."

"Go on and pull up that grease bucket, Bert," Jerry heard another voice say. "I'll keep the gun on him. I can't wait to get my hands into that lovely green grease. You know, I'll bet that tricky sheriff was hiding out, waiting on us. Man, he was really flying low when we met him on the highway. That phony tip of yours was a real smart idea."

Very quietly Jerry eased himself up on the rock ledge. Then, after a short search, he picked up a piece of broken broom handle floating near his feet and twisted it in the piano wire so that a couple of turns went around it.

A few seconds later he felt the man above fumbling and tugging at the wire.

"Come here and help me, Chauncey.

The wire must be tangled in the leaves or something, and the footing ain't very good on this slope. I sure don't want to drop the end of the wire. That kid can't go anywhere with us watching him. Take hold of that side of the stick and help me pull."

A stronger tug came on the wire, and Jerry slowly rose to his feet, giving slack. Then, grasping the piece of broom handle with both hands, he leaped from the ledge throwing his full weight onto the wire. The result was startling. Two bodies came hurtling down from above and hit the water with great splashes. A third smaller splash was made by the revolver.

When Jerry surfaced, he saw Carl leaping up the steep path as if he were a mountain goat. Listening to the men behind him spluttering and cursing as they clawed their way up on the ledge, Jerry decided Carl had a good idea; he swam quickly to the foot of the path and climbed out of the water.

The two men were starting toward him along the ledge, and he didn't even take time to remove his air tanks or swimming fins as he started a clumsy ascent up the path. Carl said afterward, that, as he watched Jerry frantically slipping and floundering on the path, all he could think of was a circus seal climbing up a stepladder to get a fish.

When the two men started to follow Jerry, Carl pelted them with stones. Jerry struggled out of the diving equipment and joined the fight at the top of the path. Using only jagged chunks of rock for weapons, the two of them easily held the men at bay until the sheriff came back a half hour later.

After the boys had explained the situation and the law officer had Chauncey and Bert safely handcuffed to the steering wheel of his car, Jerry dove down and brought up both the revolver and the end of the piano wire. The grease bucket was hauled to the surface and opened. Inside, lying on sand used for ballast, were several neat packages of currency.

"Every dollar is here," the sheriff announced when he finished counting it. "All the time those police divers were groping around on the bottom, the money was hanging right over their heads waiting to be found by a gadget like that one of yours. Those two had this planned right from the start. Instead of taking off down this road to get away from the troopers, they were heading for this quarry to hide the dough. Well, boys, that little electronic doodad of yours sure did well by you today. The insurance company has a pretty good reward out for the recovery of this money, and it's all yours."

"How about you?" Carl demanded.

"You should get a third of it. We would have been sunk if you hadn't come back when you did."

"Nope. A sheriff in this state can't accept a reward in cases like this. It's reward enough for me to see those two clowns get what's coming to them."

He paused while his eyes roved from the homemade sonar rig to the empty grease bucket. A mischievous grin spread over his face as he concluded:

"So help me, when I write up my report, I'm going to call this The Case of the Two Buckets!"

Carl & Jerry: Their Complete Adventures is now available. "From 1954 through 1964, Popular Electronics published 119 adventures of Carl Anderson and Jerry Bishop, two teen boys with a passion for electronics and a knack for getting into and out of trouble with haywire lash-ups built in Jerry's basement. Better still, the boys explained how it all worked, and in doing so, launched countless young people into careers in science and technology. Now, for the first time ever, the full run of Carl and Jerry yarns by John T. Frye are available again, in five authorized anthologies that include the full text and all illustrations."