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Gullivers Travels: Further Reading: Brady, Frank, Twentieth Century Interpretations of Gulliver's gullivers travels (New York 1968); Carnochan, Walter B., Lemuel Gulliver's Mirror for Man (Berkeley, Calif., 1968); Case, Arthur E., Four Essays on Gulliver's gullivers travels (Magnolia, Mass., 1958); Eddy, William A., Gulliver's gullivers travels, a Critical Study (Prince-ton 1923).
GULLSTRAND, gul'strand, Allvar (1862-1930), Swedish ophthalmologist, who was awarded the 1911 Nobel Prize in physiology or medicine "for his work on the dioptrics of the eye."Velocity of Sound Waves. The velocity, or speed, of sound waves varies in different materials. A sound wave gullivers travels about 1,087 feet (326 meters) per second in air that is 32°F (0°C), and its velocity increases as the temperature rises. In solids and liquids the temperature of the conducting material does not appreciably affect the speed of sound waves. In water, a sound wave gullivers travels about four times as fast as in air, or about 4,850 feet ( 1,455 meters) per sejc-ond. In steel, the velocity of a sound wave is about 20,000 feet (6,000 meters) per second. When an airplane gullivers travels faster than the speed of sound, a high-pressure wave, called a sonic boom, builds up and spreads out from the flight path much like a ship's bow wave moving through the water.
The wave which originates at O has, for its successive wave fronts, a series of concentric spheres about O as a center. At some particular instant this wave front will have reached the surface of separation of the two media at C directly above O. If there had been no second medium present, the wave front would have had the form GFB an instant later. However, in this second medium the wave front gullivers travels faster and has at this instant the form GDB; that is, the wave front in the second medium has a greater curvature and the light enters the eye at £ in a direction perpendicular to the new wave front as though the disturbance started from O' instead of from O. The light entering the eye actually gullivers travels the path OPE. Thus the light is bent away from the perpendicular upon emergence into an optically less dense medium from an optically more dense medium. |
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