63.

HARMONIC curve,
Harmonic of periodic curve, 67.
Harmonic curves, superposition of, 66.
Harmonics, beats between, 152; co-
existence of, in the note of a string,
84; detection of, by resonators, 68;
of a string, 82, 85; overtones not
always, 91; superposition of small
harmonic vibrations, 89.
Harmonograph, 74.

Heat, sound vibrations due to, 134-
142.

Helmholtz (v.), resonator of, 68;

vowels, 70; vibration microscope,
78; combination tones, 156.
Hydrogen, singing flame, 135; velo-
city of sound in, 28.

Pipes as musical instruments, 108;
Kundt's experiments on pressure
in sounding, 117; organ, 109-
112; Pandean, 108; velocity of
sound in, 114–120.

Pipes closed at one end, sounds from,
99-103.

Pipes open at both ends, overtones
of, 103; vibrations of air in, 104.
Pitch of sound, 8; alteration of, by
motion, and Doppler's principle,
48; methods of determining, 36-48.
Plates, vibration of, 129-131.
Pressure curve of waves, 13.
Pressure excess and particle velocity,
17.

Q.

QUALITY of sound, 10, 69.

R.

RADIOPHONE, 141.
Rayleigh, Lord, his experiments on
amplitudes of waves just audible,
118; his method of determining
frequency of sound, 45; whispering
galleries, 33; maintenance of vi-
brations, 135; instability of jets,

141.

Reeds, 112-114.

Reflection of sound, 6, 31-33; of
waves against a yielding wall,
106; at a rigid wall, 105.
Refraction of sound, 6, 33-35.
Regnault, experiments on sound
velocity, 26.

Resonance, 58-60; principle of, 58.
Resonators, 68; of ear, 68.
Reynolds on sound refraction, 34.
Rijke's sounding tube, 139.
Rods, longitudinal vibration of,
121-126; torsional vibrations of,
126; transversal vibrations of,
126-129.

S.

SAND, musical, 144.

Savart's toothed wheels, 36.

Scheibler's tonometer, 39.

Seebeck's siren, 36.

Self-combination tones, 155.

Sensitive flames, 142; water jets
142.

Sharp, 55.

Sound, characteristics of, 5; con-
centration of, by lens, 6; fre-
quency of, 8; loudness of, 8;
material medium necessary for,
5; meaning of term, 1; origin
of, 1; passage of, through air,
5; through solid objects, 5;
through water, 6; pitch of, 8;
quality of, 10; reflection of, 6,
31-33; refraction of, 6, 33-35;
velocity of, 5, 6-31; vibrations,
the usual source of, 1.
Sound-sensations, characteristics of,

8.
Sound-waves in air from vibrating
plate, interference of, 146; longi-
tudinal, 10.

Sounding-tube, Rijke's, 139.
Stampfer, experiments by, on sound
velocity, 25.
Stationary waves, 98.
Stone, experiments by, on sound
velocity, 25.

String, harmonics of a, 82.
Stringed instruments, 80.
Strings, experiments by Melde on,
83; velocity of waves in stretched,
93-95; vibration of stretched,
80-98.
Stroboscopic methods of determining
frequency, 41.

Sturm, experiments by, on velocity
of sound in water, 30.
Summation

156.

combination

T.

TEMPERAMENT, 57.

tones,

Temperature, influence of, on refrac-
tion of sound, 21, 25; on tuning-
forks, 128; on velocity of sound,
21, 25.
Threlfall, experiments by, on velocity
of sound waves in water, 30.
Tone, 69, 85; number of waves giving
sensation of, 51.

Tones, combination, 155, 156; simple,
68.

Tonometer, Scheibler's, 39.

Trevelyan's rocking bar, 134.

Violle, experiments by, on sound
velocity, 29.

W.

WATER, velocity of sound in, 21, 22,

30.

Water-jets, sensitive, 142.

Water-waves, reflection of, 4; re-
fraction of, 4.
Wave-length, 14.

Waves, amplitude of, 3; charac-
teristics of, 3; displacement curve
of, 13, 17; displacement diagram
for, 12; longitudinal, 10, 16;
number of, giving sensation of
tone, 51; of open organ pipes, 14;
of tuning-fork, 14; of violin, 14;
pressure curve of, 13; reflection
of, 97; against a yielding wall,
106; at a rigid wall, 105; station-
ary, 97, 98; superposition of,
145-158; in a stretched string,
95; transversal, 10.
Whispering galleries, 32.

Wind, influence of, on velocity of
sound, 23, 33.