INDEX 



Equipment: communications, 

 3; detecting, 36; echolocat- 

 ing, 107; electronic, 10; 

 electronic hearing, 30; head- 

 phones, 3; hydrophones, 

 111; oscilloscope, 60; seis- 

 mograph, 117, 118; snoop- 

 erscope viewer, 3; under- 

 water hearing, 20-21; un- 

 derwater loudspeaker, 111. 

 See Instruments 



Evolution, 104 



Eyes, 36, 54, 147; see also 

 Vision 



Facial vision, 131, 135 



False bottoms, 110, 116, 117 



Fathometers, 58, 109 



Feelers, 54 



Fish, 148; auditory sense or- 

 gans, 20; bladder, 25; de- 

 tection of, 58; echoes, use 

 of, 20; hearing, 19; noises 

 of, 20 



Fishermen, 58 



Fletcher, H., 148 



Florida, 21 



Fluctuations, 48 



Flute, 49 



FM bats, 87, 95, 97, 113, 116, 

 125 



Footsteps, 107, 138 



Frequencies, 20, 25, 29-30, 

 49, 72, 84-87; high, 72 



Fundamentals of Sonar, 148 



Hearing: aquatic animals, 19; 

 auditory nerve, 20; fish, 19, 

 20; humans, 19, 72, 99, 

 148, under water, 20, 111; 

 losses, 148; sensitivity, 46; 

 sound location, 140-42; 

 wave length, 130. See also 

 Ears 



Hearing mechanism: in fish, 

 20; in humans, 19; in por- 

 poises, 20, 24 



High-frequency note, 47 



Horseshoe bats, 84-85, 87, 

 116 



Horton, J. W., 148 



How Old Is the Earth, 118, 

 119 



Hurley, P. M., 149 



Hydrophones, 111 



Icebergs, 108, 109 



Incidence, angle of, 77 



India, 21 



Insects, 18, 148 



Instruments, 17. See Equip- 

 ment 



Interactions, 35, 42-44, 48, 51 



Interception, 18 



Interference, 50, 149; con- 

 structive, 44, 48; destruc- 

 tive, 44 



Jamming, 103, 148 

 Jurine, Charles, 28 



Galambos, Robert, 29 

 Ganges River, 21 

 Griffin, Donald R., 148 



Hairs, 53, 54 

 Harmonics, 49 

 Harvard University, 29 



Lawrence, Barbara, 22, 23, 

 25, 99 



Light, 18, 36, 42, 129, 130; 

 velocity in water, 19; in 

 water, 18-19 



Light waves, 53, 80; reflec- 

 tions, 70 



Liquids, 40 



153 



