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115

Ocean, density of the, 51, Precession and nutation,
60; of the Pacific, 88;

93, 95
tides, 108

Probabilities, the theory of,
Optics, 172, 179, 210, 223 71
Orinoco, cataracts of the, Problem of the three bodies,
147

69
Otaheite, observations by Proportion, law of definite,
Cook at, 64

129
Pallas, planet, 68

Quadrupeds, 283
Papyrus, date of a MS., 106, Radiation, principle of, 239

Rays of light, 163, 165, 198,
Parallax, definition, 61

220
Parry, Sir Edward, 123, 310

of heat, 228-238
Pendulum, oscillations of Reflection, phenomena of
the, 58-61, 106

luminous, 169, 170; law

of, 250
Perpetual motion, 323
Phases of the moon, 42

Refraction of light, 164, 166;

double image, 199, 202
Phenomena of refraction,

Retina, images, accidental
166 et seq.; prismatic,

image, and imagination,
172, 188; of periodical

180
colours, 223

Richter's observations at
Plane of the centre of gravi-
tation, fixed, 22, 24

Cayenne, 61

Rivers, declension in the
Planetary eclipses, 46

bed of, 53, 80
Planets, theory of the, 11

Ross, Captain, 311
their masses, 66

Rotatory motion, 325, 341
the minor, 16, 68

of the earth, 33; of
orbit varied, 11 planets, how proven, 72
Plants of various climes, Salt, rock, permeable to
276, 278

rays of heat, 232
Platina wire, 340

Salt and sugar, attraction
Poinsot, theory of M., 23

or absorption by, 127
Polarity of the magnet, 317

Sap, vegetable, experiments,

217
Polarization of light, the,
195, 207; experiments,

Satellites, law of planetary,

7, 26
212, 214, 317
Poles, the, 83, 87

Saturn, the planet, 24
of maximum cold,

description of, 74,96
268

Scoresby, Captain, 168

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3

Thermo-electricity, 356
Thermometer, the, 123, 125
Thunder, 151
Tides, described, 108
Time, mean solar, 98; deci.

mal division, 98, 107
Torpedo, the, 308, 356
Tourmaline, 209, 211
Trade-winds, the, 122, 135
Universe, the, 22, 374
Uranus, his satellites, 31;

distance from the sun, 64,

253
Vegetation influenced by the

decrease of temperature,
272; extraordinary, 273;
comparison of various ex.

amples of, 274
Velocity of light, 33, 187 ;

of sound, 144; of electri.
city, 151; of coloured

rays, 226

Venus, the transits of, 62;

climate of, 255
Voltaic electricity, 303, 332

vibrations, aërial, 141,
224; of elastic bodies, 152;
of sonorous bodies, 154; of

light, 219
Water, a conveyer of sound,

145, 152
Waves, description, 118
Week, 100
Year, the, and the seasons,
· 93, 97, 102
Zinc, oxidation of, 300

Sea-weed, 280
Shadow of the earth, 42
Shell-fish, 282
Shells, marine and fossil, 86
Sidereal astronomy, 386-95
Sight, sense of, 233
Silence of the night, 148
Sirius, 385
Solar eclipses, 44
Solstices, the, 103
Sound, theory of, 131, 137,

22+
Snow, perpetual, 260
Space, the immensity of, 407
Spar, Iceland, 199, 202
Spectrum, the solar, 228-38
Stars, the fixed, 23, 65, 333;

magnitude of the fixed,
385 ; first observation
made of some, 386; some
disappear, and at certain
periods re-appear, 387;
binary or double stars,

392; colours of, 393
Steam, elasticity and ex-

pansion, 248
Sun, the, is the centre of

universal gravitation, 7;
distance of, 47 ; parallax
of, 63; rotation of, 72;
the solstices, 103; the

sunbeam, 172
Syrup, physical facts, 215
Temperature, observations,

82, 85, 256, 271, 272

TUR END.

Ro

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