INDEX..

[The Numbers refer to the Articles of the Text.]

ACOUSTICS, its objects as a science, 1.

AIR. Propagation of Sounds in, Part I., Chap. I. and II.; con-
densed and rarefied sounds in, 2; sound at great elevations in,
3; its temperature, moisture, and other circumstances affecting
sound, 5, 6, 21; heat developed in, increases the velocity of
sound, 22; vibrations of a column of, Part II., Chap. III., 156;
vibrations of, 152, 155, 157, 158; in contact with vibrating surfa-
ces, 160, 163, 166, 183.

Air-pump, sounds in the exhausted receiver, 2.

Atmosphere, sounding, its probable extent, 3.

Beats, in music, 112; rendered ocularly visible, 154.

Bird-calls, 192, b.

Bullet, singing of, explained, 52, b.

Carpets, effects in deadening sound in a room, 37.

Cavities, resonance of, 157, 158; of the tympanum, 186; of the
pharynx, 193, 196 b.

Chimney Pipes, 96.

Chords, in music, 99, 106, 107; vocal, 192.

Chromatic Scale, 110.

Clouds, reverberations of sound by, 12.

Cochlea of the ear, 187.

COLUMN OF AIR, vibrations of, Part II., Chap. III.; resemblance to
those of a stretched cord, 69; reflection at the end of the column,
70; how maintained, 71, 77, 84; nodes, 72, 73, 74, 79, 80, 81, 156.
Concords, musical, 99, 106, 107.

Consonants, how produced, 196.

CORD STRETCHED, vibrations of, 13; Part II., Chap. II.,

how pro-
duced and maintained, 53, 63; investigated, 54; reflected from the
fixed ends, 56, 57, 65; duration of, when fixed at both ends, 57,
58; nodes and ventral segments, 59, 60; harmonics, 60, 61; pitch,
66; form of orbits, 67.

CRISPATIONS, on the surface of fluids over vibrating plates, 167-182;
of air in contact with vibrating surfaces, 183.

CURRENTS, in a fluid in contact with vibrating surfaces, 160-164, 166.
Cylinder, vibrations of See. Tube.

DECAY of sound, Part I., Chap. VI.

Diapason organ pipe, 86, 87.

Diatonic scale, 103.

Discords, musical, 98; resolved, 100.

Distance, at which sounds have been heard, 6.

DIVERGENCE, of sound, Part I., Chap. VI; not alike in all direc-
tions, 45, 152.

EAR, its structure, Part III., Chap. IV.; the outer, 185; the middle,
186; the inner, 187.

Echos, from walls, 8, 9, 10; from curved surfaces, 11; from clouds, 12.
Elasticity of a solid, 33.

Embouchure, of a pipe, 74, 85, 156; may command the pipe, 93, 94.
Euphone, musical instrument of Chladni, 140.

Eustachian tube, 186.

Falsette, 199.

Fishes, hearing of, 26.

Foramens of the ear, 186.

Flats and sharps in music, 109.

FLUIDS, in contact with vibrating surface, forms and states of, Part
III., Chap. III; currents, 160 – 164, 166; crispations of, 167 – 183.
Forces, transmitted by solids, 43.

GASES, propagation of sound in, Part I., Chap. III.; in mixed gases,
35, 36.

Glottis, 192.

Harmonica, German, 92.

Hormonics, 99; of a stretched cord, 60; of pipes, 81, 87; of a vibrat-
ing rod, 121; of solids, 122, 150.

HARMONY, musical, Part II., Chap. IV.

Harp, Jew's, 91.

Hearing, of fishes, 26; of sounds under water, 26; by night more

delicate than by day, 35; limits of, 104, 105; organs of, Part III.,
Chap. IV.

Heat, developed in air, cause of the difference between theory and
observation, 22; developed in gases and vapors, 24; not developed
in liquids, 29.

HUMAN VOICE, organs of, Part. III., Chap. V.; organ-pipes, 96.
Hydrogen, propagation of sound in, 24; curious effects on the sound,
25, 36.

Influence, mutual, of vibrating bodies, 141.

Intensity of Sound, 50; in air of different densities, 2, 3; causes
affecting it, 5, 6, 7; in gases and vapors, 25; in passing from one
medium to another, 26 c; law of its decay by distance, 46.
Intervals, musical, 102; scale of equal, 114.

Jew's harp, 91.-

Labyrinth of the ear, 187.

Larynx, 192.

LIQUIDS, Propagation of Sound in, Part I., Chap. IV., 159; in con-
tact with vibrating surfaces, Chap. III., Part III. See Fluids.
MATHEMATICAL THEORY of the Propagation of Sound, Part I.,
Chap. II.; in liquids, 28.

MEDIA, MIXED, Propagation of Sound in, Part I., Chap. V.; un-
fitted to convey sound, 34, 35, 36, 37.

Membranes stretched, vibrations of, 152, 153, 192 c; used to explore
the vibrations of air, 154, 155, 156; of the ear, 186.

Meteors, sounds of, 3, 4.

Monochord, 62.

Mountains, high, sounds on, 3.

MUSICAL SOUNDS, Part II.; under water, 31; distinguished from
noise, 48, 49, 50; production of, 51, 52.

MUSICAL Intervals, Harmony, and Temperament, Part II., Chap. IV.
Nerves of the ear, 187; of the voice, 189.

Nodes, of a stretched cord, 59, 60, 61, 63; of a column of air, 72,
73, 74, 78, 79, 80, 81, 156; of a vibrating rod, 122, 147; of a
vibrating plate, 126, 147, 151; of a vibrating solid, 145; of vibrat-
ing tubes, 148, 149, 150; of vibrating air in a chamber, 155; of
a vibrating stretched membrane, 152, 153.

Noise, distinguished from musical sounds, 48.

Notes, musical, 97, 109; not in unison, 98, 108; two may produce
a third, 113.

Organ-pipe, diapason, 86, 87; vox humana, 95; chimney, 96.
Pharynx, 193; important in articulation, 196.

Phenomenon, curious, at the Solfaterra, 38.

PIPES, sound conveyed in, 7; pyramidal, propagation of sound in, 46;
vibrations of air in, Part II., Chap. III.; embouchure of, 74, 85;
open at both ends, 79, 80; closed at both ends, 75, 80; open at
one end, 75, 76, 77, 80; pitch of, 80, 81, 82, 85; qualities of, 84,
88, 89; of different materials, 83; organ, 86, 87, 95, 96; with a
reed, 88, 89, 90; lengths of, which yield the vowels, 195.
Pitch, 50, 97, 117: of a stretched cord, 66; of a pipe, 81, 82, 85,
87; of reed pipes, 88; of vibrating plates, 129, 138; of the voice,
191 – 194, 199; of whistling, 198.

-

Plates, transverse vibrations of, 126, 128, 135, 136, 137, 143, 151;
rendered visible to the eye, 127; primary vibrations of, 130; super-
positions of vibrations, 128, 129, 131 – 135; tangential vibrations
of, 147, 151.

Powder, fine, strewed on vibrating plates, to indicate the currents of
fluid in contact with the plates, 161, 162, 163; arranged in heaps,
165; strewed over the crispations of a fluid, 173.

PROPAGATION OF SOUND, in Air, Part I., Chap. I. and VI.; mathemati-

cal theory, Part I., Chap. II.; mode of, 13; in a straight canal of
equal bore, 18; in gases and vapors, Part I., Chap. III.; through
liquids Part I., Chap. IV.; in solids and mixed media, Part I.,
Chap. V.

Pulses, aerial, 16, 47.

Quality of Sound, 50; of the tones of different pipes, 84, 88, 89,
90; of the voice, 191 – 199.

Receiver, exhausted, sounds quite inaudible in, 2.

Reed, attached to a pipe, 77, 88, 89, 90; Grenié's reed, 90, 91, 92.
Reflection of sound from walls, 8, 70; law of, 9; total, in passing
from a denser to a rarer medium, 30.

Resonance of a cavity, 157, 158; of the pharynx, 193, 199 d.
Rods, longitudinal vibrations of, 120, 121, 143, 145, 147, 148, 150;
harmonies of, 121; transverse vibrations of, 124; vibrations com-
municated to solids, 140, 141, 142.

Sand, arranged on the nodal lines of vibrating bodies, 127, 129, 132,
134, 135, 136, 146, 149, 151, 152, 153, 159; below the crispa-
tions of a fluid on vibrating plates, 172.

Scale, diatonic or natural, 103; chromatic, 109, 110, 111; iso-har-
monic, 114; of mean tones, 116.

Shadows of sound in water, 32.

Sharps and flats, 109.

Sirene, of M. Cagniard de La Tour, 51, b.

SOLIDS, Propagation of Sound in, Part I., Chap. V.; homogeneous,
uniform in structure, and the reverse, 34; elasticity of, 33;
difference between solids and fluids in conveying sound, 39, 40, 41;
forces transmitted by, 43; vibrations of, 117, 118, 119, 122, 123,
140, 141, 142, 143, 146.

SOUND, its propagation, Part I.; velocity of, 5, 19–24, 27, 28, 42,
82; intensity of, 2, 3, 6, 7, 25, 26, 50; reflected, 8, 9, 10, 11;
equations of motion, 18; total reflection, 30; change of its nature
in passing through water, 31; shadows in water, 32; not well con-
veyed through non-homogeneous substances, 34, 35, 36, 37; better
heard by night than by day, 35; divergence and decay, 44, 45,
46; MUSICAL, Part II.; pitch of, 50, 66, 81; quality of, 50.
Sounding-boards, effect of, 139.

Strings, tended. See Cord.

SYSTEMS, Vibrations of, Part III., Chap. I.

Temperament, musical, 108, 111, 112, 115; system of equal, 114;
different systems of, 116.

Temperature of the medium affects the velocity of sound, 5, 21.
THEORY, Mathematical, of the Propagation of Sound, Part. I.,
Chap. II.

Thorax, 190.

Thunder explained, 12.

Trachea, 191.

Tubes, vibrations of, 148-150; Eustachian, 186.

Vacuum, will not convey sound, 2.

VAPORS, Propagation of Sound in, Part I., Chap. III.

Velocity of Sound in air, 5, 19, 82; circumstances affecting, 5, 21;
independent of the density of air, 20; difference between theory
and experiment, 22; in gases and vapors, 23, 24; in water, 27;
in liquids, 28; in solids, 42.

VIBRATIONS of a stretched cord, 13, Part II., Chap. II.; of a column
of air, Part II., Chap. III., 156; superposition of, 61, 94, 128, 129,
131-135; of bars, rods, and plates, Part II., Chap. V.; of sys-
tems, Part III., Chap. I.; Communication of, 137, 140, 141, 143,
Part. III., Chap. II; of the air, 152, 153, 155, 157, 158; of a
liquid, 159.

Violin, vibrations of, 137; improvement of, 144.