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Short Stories of Science and Invention

A Collection of Radio Talks by
Charles F. Kettering


51.   Catching Up With Nature

     Using the most modern sound recording devices the men found that while in flight the bat emits a sound which has a frequency of vibration reaching a maximum of about 80,000 cycles - or, in musical terms, about 8½ octaves above middle "c." We call these sounds "supersonic" because their pitch is so high they cannot be heard by the human ear. Our range of hearing is somewhat greater than the highest note produced by instruments of the orchestra. The harmonics on the E string of the violin are about 10,000 cycles per second. Apparently, the bat while in flight sends out these inaudible sounds in short squeaks which strike the obstacle he is approaching and are reflected back and are picked up by his sensitive ears in time for him to steer clear of the object.

Ship     This method of sound reflection has been used for many years to determine the depths of the ocean and the pilots of boats in Alaskan waters often use the echo of their boat whistles to determine if they are getting too near the cliffs when travelling in dense fog. Many other applications of this system are in daily use in laboratories for determining faults in materials and undoubtedly after the war it will be applied in many other ways.

Birds     We feel proud of our recently developed sound echo devices even though the bat has been using it in the dark for thousands of years. We marvel at the automatic flying instrumentation of planes but every year flocks of birds go from their southern homes to their northern ones and return to precisely the same location with only their natural instrumentation.


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- 100 -
Sophie Germain
Gertrude Elion
Ernest Rutherford
James Chadwick
Marcel Proust
William Harvey
Johann Goethe
John Keynes
Carl Gauss
Paul Feyerabend
- 90 -
Antoine Lavoisier
Lise Meitner
Charles Babbage
Ibn Khaldun
Ralph Emerson
Robert Bunsen
Frederick Banting
Andre Ampere
Winston Churchill
- 80 -
John Locke
Bronislaw Malinowski
Thomas Huxley
Alessandro Volta
Erwin Schrodinger
Wilhelm Roentgen
Louis Pasteur
Bertrand Russell
Jean Lamarck
- 70 -
Samuel Morse
John Wheeler
Nicolaus Copernicus
Robert Fulton
Pierre Laplace
Humphry Davy
Thomas Edison
Lord Kelvin
Theodore Roosevelt
Carolus Linnaeus
- 60 -
Francis Galton
Linus Pauling
Immanuel Kant
Martin Fischer
Robert Boyle
Karl Popper
Paul Dirac
James Watson
William Shakespeare
- 50 -
Stephen Hawking
Niels Bohr
Nikola Tesla
Rachel Carson
Max Planck
Henry Adams
Richard Dawkins
Werner Heisenberg
Alfred Wegener
John Dalton
- 40 -
Pierre Fermat
Edward Wilson
Johannes Kepler
Gustave Eiffel
Giordano Bruno
JJ Thomson
Thomas Kuhn
Leonardo DaVinci
David Hume
- 30 -
Andreas Vesalius
Rudolf Virchow
Richard Feynman
James Hutton
Alexander Fleming
Emile Durkheim
Benjamin Franklin
Robert Oppenheimer
Robert Hooke
Charles Kettering
- 20 -
Carl Sagan
James Maxwell
Marie Curie
Rene Descartes
Francis Crick
Michael Faraday
Srinivasa Ramanujan
Francis Bacon
Galileo Galilei
- 10 -
John Watson
Rosalind Franklin
Michio Kaku
Isaac Asimov
Charles Darwin
Sigmund Freud
Albert Einstein
Florence Nightingale
Isaac Newton

by Ian Ellis
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