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Bud nodded grimly. "But staying just out of sonar range from the base." The jetmarine closed steadily on its quarry. In a few minutes they were able to make it out dimly through the cabin window, dead ahead. "That's sure no U.S. Navy sub that I know of," Bud said. "Probably an enemy snooper." "What if they spot us?" Zimby asked. Bud chuckled. "That's the beauty of it, pal! Don't forget.
And I think I see a way to do it." "How?" "So far, I have been thinking about refining our own search sonar." Tom explained that the new system he had in mind would send out a complex pulse that is, an underwater sound wave with many harmonics instead of a single tone, sharp-peaked sound impulse. "This will make it less likely that their antidetection gear will absorb all of it," Tom went on.
"Now what're you fixin' to do with it?" "This will be fed into the diver's sonar along with his own noise output," Tom said, "to make him sound like a porpoise." Chow howled. "That I've got to hear!" The young inventor worked feverishly throughout the day and into the next, perfecting his new "porpoise sonar."
"It's mostly a job of adapting the sonarphone arrangement from our Fat Man suits in miniature." A tiny mike, Tom explained, would be installed on the inside of each face mask, with its output feeding to a sonar transducer on the exterior. The receiving transducers would feed from amplifiers to earphones.
Deep in thought, Tom idly fingered a microphone on his workbench. "In fact," the young inventor mused, "why not go them one better? I'll invent a submarine that's not only invisible to sonar, but equipped to see them!" Random hunches and circuit diagrams flashed through Tom's brain.
It did! Light slowly dawned. "Then these were scanning our subs! But I still don't see why it would be any problem to find them. The subs must have equipment that will tell when sonar beams hit them." "They do. And that's a big part of the story." Steve sipped his coffee for a moment. "These sonar devices are a new type, and very cleverly designed. They don't send out a continuous beam.
Very high frequency sound impulses were sent out, and the echoes were timed or used in other ways. It was the way in which bottom tracings were made by surface craft, and the way in which Navy ships detected submarines. It could be used for locating schools of fish. "It could be sonar of some kind," Rick agreed. "But what good would it do anyone to stick a sonar device on an island like this?"
I recommend to the notice of those who wish to understand the character of that extraordinary man, the recital of the nocturnal vision, in which he imagined that he heard a celestial voice, in the midst of a tempest, encouraging him by these words: Iddio maravigliosamente fece sonar tuo nome nella terra.
Thus the sonar waves would appear to be striking no obstacle and no echo would return to the sonarscopes on the search craft! "Jumping jets!" Tom thumped his fist on the workbench in his excitement. "I'll bet that's the answer, all right!" He grinned. "Brand my boot heels, it's partly due to good old Chow!" He grabbed a pencil and began sketching his idea on paper.
DOÑA MATILDE. No, papá duerme todavía y estará sin duda bien lejos de soñar o de pensar que el terrible momento se aproxima en que va a decidirse para siempre el porvenir de su hija única y querida ... ¡para siempre! Ay, Bruno, si tú pudieras comprender toda la fuerza y la extensión de esta palabra ¡para siempre!
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