SUNBEAMS.

TEMPERATURE.
atmospheres, ib. ; variations in heat impelled in the direction of, 8;
and light emitted from, 225, 226; force, disturbing, in the direction of,
amount of heat annually received by 14, 15; deflection from, a mea-
the earth from, 238; effect of his surement of centrifugal force, 49.
brilliancy on the heat emitted by, Tangential force, occasioning secular
259 ; his position affecting varia- inequalities, 14; effects produced
tions in the magnetic elements, 343, by, 15; producing the variation
344; connexion between periodic of the moon, 35; force acting on
variation in his spots and in the the sea, 100.
magnetic elements, 344 ; vast sweep velocity, effects produced by
of his gravitating force, 365; in- modifications of, 16; undiminished
creased attraction of, for comets, by the ethereal medium, 22.
372; gulfs separating stars from, Telegraph, the electric, discovery
390; possibility of change in his leading to the invention of, 323,
lustre, 394 ; spot on, measured by 324; the Atlantic, 325; principles
Sir John Herschel, 394, 395; pro- of its construction, 326, 327 ; date
portion of his light to the moon's, of its completion, 327.
404; rate and orbit of motion with Telegraphs, land, principle of their
his system, 405, 406; a nebulous construction, 328.
star, 412; meteoric nebula revolv- Telescope, the achromatic, principle
ing round, 422 ; gravitating force of its construction, 164.
of, 424, 425.

the differential, differences in
Sunbeams, resolved into their com- illumination determined by, 227.

ponent colours, 159-162 ; law pre- Lord Rosse's, nebulæ resolved
vailing in the phenomena of, 198; by, 407, 415.
light a distinct property of, 214; Telescopium, comet traversing the con-
resolved into three spectra, 222; stellation of, 379; nebula in, 414,
undulations constituting, 223 ; their Temperature, a decrease in, affecting
influence on vegetation, 249.

the earth's rotation, 72; excen-
Swan, the, vanishing star in, 393. tricity of the terrestrial orbit, a
Switzerland, meteors falling in, 421. cause of decreasing, 73; law equal-
Syene, arc of the meridian measured ising, 74; geological changes af-
between Alexandria and, 49.

fecting, 75.
Sykes, Colonel, extensive range of cul- -, varying in the terrestrial at-

tivation of wheat observed by, 250. mosphere, zone of constant, 119;
Sympathetic vibrations in musical in- affecting atmospheric undulations,
struments, 147-149.

121; modifying the velocity of
Syren, the, an instrument ascertaining sound, 134; chemical action of

the number of musical pulsations in light affected by, 218-222; of the
a second, 143.

ethereal medium, 227, 228 ; under-
Syzigies, tides increased in the, 96. ground stratum of constant, 228;

rate of increase in, below the earth's
TABLE-LANDS, high, influence of, on crust, 228, 231 ; of the ocean,
the atmosphere, 241.

231 ; mode of finding annual aver-
Tail of comets, sudden development age, 239; causes of disturbance

of, 372; forces producing, 375; in regular variation of, 240-245;
unequal illumination of, 375, 376; variations in the same latitude,
change in position of, 376; divided, 246, 247 ; influence of, on vegeta-
ib.; constitution of, 377.

tion, 248; affecting transmission
Talbot, Fox, his inventions in photo- of heat, 259, 260 ; of solid bodies,
graphy, 204,

caused by absorption of rays, 268;
Tangent, a, to planetary orbits, planets affecting the length of the pendu-

TENERIFFE.

TOURMALINE,
lum, 272 ; causes of perpetual light, 279 ; investigation into the
variations in, 274; transmission of relations of light and magnetism,
electricity affected by, 284; affect- 320; density of the ethereal me-
ing magnetism, 352.

dium computed by, 356; magnetic
Teneriffe, the Peak of, prevailing property of the ethereal medium

winds on, 124; lunar heat on, 227; pleaded for, 357.
zones of vegetation, 250 ; character Thunder, theory of prolonged peals of,
of its flora, 252.

138.
Terrestrial globe, the, a magnet, 336. Tidal wave, theory of, 92; its birth-

- magnetism, 341-343; the three place, 93; course of, 93, 94 ;
elements and their variations, 343, velocity, 94; effect of depth on its
344; storms, period of their varia- motion, 95.
tion, 344; its connexion with solar Tides, calculation from the moon's
magnetism, ib.; effect of atmo- action on, 55; theory of forces
spheric magnetism on, 345; pro- producing, 91, 92; circumstances
bable cause of, 346; effect of occasioning irregularities, 93; ris-
planetary magnetism on, 346, 347. ing, progress of, 93, 94; three
meridian, a, defined, 46.

kinds of oscillations in, 95, 96;
Tessular system of crystallization, 108. variations in, from lunar and solar
Texas, monsoons occasioned by its influence, 96-98; effect of inter-
deserts, 124.

ference of waves on, 99; the sea's
Thames, the, period occupied by the equilibrium underanged by, 100.
tidal wave in reaching, 94.

-, lunar and diurnal, of the ter-
Thaw, cause of the sensible chilliness restrial atmosphere, 121; examples
of, 276.

of sympathetic undulation, 148.
Theory of probabilities, use of, in Time, a measure of motion, 58; a

determining astronomical data, 60. measure of angular motion, 83;
Thermo-electric currents, discovery

difference between mean and ap-
of, 332 ; phenomena exhibited by, parent solar, 84; mean equinoctial,
333; principle of, applied to mea- mode of computing its object, 86 ;
suring heat, 333, 334.

estimation of, corrected by means
Thermography, examples of, 219- of laws of unequal expansion, 272.

Timocharis, comparison of his obser-
Thermometer, the, principles applied vations with Hipparchus, 80.

to the construction of, 113; con- Tomboro, submerged in a volcanic
sulted in determining mountain eruption, 233.
heights, 119, 120; refraction vary- Torpedo, the, electrical action of, 310,
ing with, 154 ; heat measured by 311,
motion in, 274.

Torrecelian vacuum, experiment on
Thermoin ultiplier, use of, in experi- the electric discharge in the, 306 ;

ments, 264; principle of its con- lines of magnetic force passing
struction, 333, 334.

through, 344
Theta Orionis, the multiple system Torronto, observations on magnetic
of, 395.

storms at, 346.
Thibet, wheat ripening in, 250. Toucan, comet approaching the con-
Thomas, St., the island of, hurricane stellation of, 379; a nebula in, 414.
with pauses at, 127.

Toucani, 47; globular nebulous clus.
Thomson, W., Professor, experiments ter, 414.

of, in freezing water, 271 ; dyna- Tourmaline, brown, light polarized
mical theory of heat maintained by prisms of, 180; property quali-
by, 275 note; his calculation of fying it to analyze polarized light,
the force exerted in vibrations of 182; coloured images produced by,

221.

SUNBEAMS.

TEMPERATURE.
atmospheres, ib.; variations in heat impelled in the direction of, 8;
and light emitted from, 225, 226; force, disturbing, in the direction of,
amount of heat annually received by 14, 15; deflection from, a mea-
the earth from, 238; effect of his surement of centrifugal force, 49.
brilliancy on the heat emitted by, Tangential force, occasioning secular
259 ; his position affecting varía- inequalities, 14; effects produced
tions in the magnetic elements, 343, by, 15; producing the variation
344; connexion between periodic of the moon, 35; force acting on
variation in his spots and in the the sea, 100.
magnetic elements, 344 ; vast sweep velocity, effects produced by
of his gravitating force, 365 ; in- modifications of, 16 ; undiminished
creased attraction of, for comets, by the ethereal medium, 22.
372; gulfs separating stars from, Telegraph, the electric, discovery
390; possibility of change in his leading to the invention of, 323,
lustre, 394 ; spot on, measured by 324; the Atlantic, 325; principles
Sir John Herschel, 394, 395; pro- of its construction, 326, 327; date
portion of his light to the moon's, of its completion, 327.
404; rate and orbit of motion with Telegraphs, land, principle of their
his system, 405, 406; a nebulous construction, 328.
star, 412 ; meteoric nebula revolv- Telescope, the achromatic, principle
ing round, 422 ; gravitating force of its construction, 164.
of, 424, 425.

the differential, differences in
Sunbeams, resolved into their com- illumination determined by, 227.

ponent colours, 159-162 ; law pre- Lord Rosse's, nebulæ resolved
vailing in the phenomena of, 198; by, 407, 415.
light a distinct property of, 214; Telescopium, comet traversing the con-
resolved into three spectra, 222; stellation of, 379; nebula in, 414,
undulations constituting, 223; their | Temperature, a decrease in, affecting
influence on vegetation, 249.

the earth's rotation, 72; excen-
Swan, the, vanishing star in, 393. tricity of the terrestrial orbit, a
Switzerland, meteors falling in, 421. cause of decreasing, 73; law equal-
Syene, arc of the meridian measured ising, 74; geological changes af-
between Alexandria and, 49.

fecting, 75.
Sykes, Colonel, extensive range of cul- -, varying in the terrestrial ata

tivation of wheat observed by, 250. mosphere, zone of constant, 119;
Sympathetic vibrations in musical in- affecting atmospheric undulations,
struments, 147-149.

121; modifying the velocity of
Syren, the, an instrument ascertaining sound, 134; chemical action of

the number of musical pulsations in light affected by, 218-222 ; of the
a second, 143.

ethereal medium, 227, 228 ; under-
Syzigies, tides increased in the, 96. ground stratum of constant, 228;

rate of increase in, below the earth's
TABLE-LANDS, high, influence of, on crust, 228, 231 ; of the ocean,
the atmosphere, 241.

231 ; mode of finding annual aver-
Tail of comets, sudden development age, 239; causes of disturbance

of, 372; forces producing, 375; in regular variation of, 240-245;
unequal illumination of, 375, 376; variations in the same latitude,
change in position of, 376; divided, 246, 247; influence of, on vegeta-
ib.; constitution of, 377.

tion, 248; affecting transmission
Talbot, Fox, his inventions in photo- of heat, 259, 260 ; of solid bodies,
graphy, 204,

caused by absorption of rays, 268 ;
Tangent, a, to planetary orbits, planets affecting the length of the pendu-

TENERIFFE.

TOURMALINE,
lum, 272 ; causes of perpetual light, 279; investigation into the
variations in, 274; transmission of relations of light and magnetism,
electricity affected by, 284; affect- 320; density of the ethereal me-
ing magnetism, 352.

dium computed by, 356; magnetic
Teneriffe, the Peak of, prevailing property of the ethereal medium

winds on, 124; lunar heat on, 227; pleaded for, 357.
zones of vegetation, 250; character Thunder, theory of prolonged peals of,
of its flora, 252.

138.
Terrestrial globe, the, a magnet, 336. Tidal wave, theory of, 92; its birth-

magnetism, 341-343; the three place, 93; course of, 93, 94;
elements and their variations, 343, velocity, 94; effect of depth on its
344 ; storms, period of their varia- motion, 95.
tion, 344; its connexion with solar | Tides, calculation from the moon's
magnetism, ib.; effect of atmo- action on, 55; theory of forces
spheric magnetism on, 345 ; pro- producing, 91, 92; circumstances
bable cause of, 346; effect of occasioning irregularities, 93 ; ris-
planetary magnetism on, 346, 347. ing, progress of, 93, 94; three
meridian, a, defined, 46.

kinds of oscillations in, 95, 96 ;
Tessular system of crystallization, 108. variations iri, from lunar and solar
Texas, monsoons occasioned by its influence, 96-98 ; effect of inter-
deserts, 124.

ference of waves on, 99; the sea's
Thames, the, period occupied by the equilibrium underanged by, 100.
tidal wave in reaching, 94.

lunar and diurnal, of the ter-
Thaw, cause of the sensible chilliness restrial atmosphere, 121; examples
of, 276.

of sympathetic undulation, 148.
Theory of probabilities, use of, in Time, a measure of motion, 58; a

determining astronomical data, 60. measure of angular motion, 83;
Thermo-electric currents, discovery difference between mean and ap-

of, 332 ; phenomena exhibited by, parent solar, 84; mean equinoctial,
333; principle of, applied to mea- mode of computing its object, 86 ;
suring heat, 333, 334.

estimation of, corrected by means
Thermography, examples of, 219- of laws of unequal expansion, 272.
221.

Timocharis, comparison of his obser-
Thermometer, the, principles applied vations with Hipparchus, 80.

to the construction of, 113; con- Tomboro, submerged in a volcanic
sulted in determining mountain eruption, 233.
heights, 119, 120; refraction vary- Torpedo, the, electrical action of, 310,
ing with, 154 ; heat measured by 311.
motion in, 274.

Torrecelian vacuum, experiment on
Thermo:n ultiplier, use of, in experi- the electric discharge in the, 306 ;

ments, 264; principle of its con- lines of magnetic force passing
struction, 333, 334.

through, 344.
Theta Orionis, the multiple system Torronto, observations on magnetic
of, 395.

storms at, 346.
Thibet, wheat ripening in, 250. Toucan, comet approaching the con-
Thomas, St., the island of, hurricane stellation of, 379; a nebula in, 414.
with pauses at, 127.

Toucani, 47 ; globular nebulous clus.
Thomson, W., Professor, esperiments

ter, 414.
of, in freezing water, 271 ; dyna- Tourmaline, brown, light polarized
mical theory of heat maintained by prisms of, 180 ; property quali-
by, 275 note; his calculation of fying it to analyze polarized light,
the force exerted in vibrations of 182; coloured images produced by,

TRADE.

space, 424.

VALZ.
186, 187; changed by compression, luminous ether, 169, 170; in re-
189; heat polarized by, 265; elec- fraction and reflection, 177 ; pro-

tricity communicated to, 284. ducing fluorescence, 197; different,
Trade winds, friction of, not affecting in light and sound, 199, 200 ; con-

the earth's velocity, 72; action on stituting a sunbeam, 223; heat
the general motion of the sea, 100 ; propagated by, 267 ; of light, evolu-
system of, accounting for atmo- tion of latent force in extinguished,
spheric anomalies, 120 ; theory 279, 280; of natural forces identi-
of their origin, phenomena con- cal, 281.
nected with, 122, 123; becoming Undulatory theory of light, 168-170;
monsoons, 124.

law of motion affecting, 176, 177 ;
Transits of Venus, 52, 53.

phenomena proving, 198; objection,
two consecutive, of any star, a from the different action of light
measure of time, 83.

and sound, refuted, 199; proving
Transmission of radiant heat, 258, the existence of the ethereal medium,

262; of electricity, 284, 285 ; of 358; acceleration in comet's mo-
voltaic electricity, 298 ; molecular tion proving, 367.
structure affecting, 303; method theory, experiments determin-
of, determining the influence of ing in favour of, 200, 201 ; final
electric currents, 317; of gravity, and decisive experiment, 202; of
an unsolved question, 355 ; pro- heat, 267.
bable agent, 356 ; medium of, in Unison, note in, 142.

United States, astronomical observa-
Transparent bodies, temperature of, tions made in, 371, 373.

unaffected by the sun's rays, 227. Uranium, phosphorescent property of,
Trees, number of species of forest, 296 ; peculiar luminous properties
found in America and Europe, 252.

of, 296.
Tribes, apparently distinct, of the Uranus, effect of reciprocal attraction
human race, 255.

between Neptune and, 22 ; periods
Triple stars, 395; periods of revolu- of the revolutions of his satellites,
tion in, 400.

33; distance from the sun, 54 ;
Tropical year, change in its length, astronomical tables of, 60; disco-

80 ; period of, 83 ; difficulty of very suggested by his perturbations,
adjusting its estimation, 85.

61; observations on, leading to
revolution of the major axis of Neptune's discovery, 62; sun's in-
the solar ellipse, its period, 86. fluence in, 225; action of, on Hal-

vegetation, the luxuriance of, ley's comet, 363; appearance of the
248.

sun to, 380, 381; comets in his
Tuileries, clock in the, showing deci- orbit, 381, 382.
mal time, 84,

Ursa Major, periodic time of a double
Twilight, caused by refraction, 154; star in, 398; nebulous region of, 417.
effect of reflection, 158.

Utah, deserts of, causing monsoons,
Tyndall, Professor, his experiments 124.
proving diamagnetic polarity, 348;
on magnetic action in crystals, 349. VACUUM produced by shell-fish, 117;

a