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MAGNETS.

ing, 322; machine constructed on
the principle of, 325; relation of
heat to, 329.
Magnets, influence of, on electric light,
307; fish possessing the power of
making, 311; effect of an electric
stream on, 312-314; obtained by
electricity, 315; power of electro,
measured, 315; cylinders acting as,
316, 317; producing electrical
effects, 322, 323; evolving elec-
tricity by rotation, 330; classifica-
tion of substances in relation to,
332; polarity a property of, 336;
effect on themselves of imparting
paramagnetism, 337; experiment
showing the lines of force of, 338;
properties of, indestructible by sub-
division, 338, 339; the earth
reckoned among, 342; planets
reckoned among, 346; action of an
electro, on copper, 351.
Maguire, Captain, his observations on
magnetic storms, 345, 346.
Malo, St., rising of the tide at, 98.
Malus, M., discovery of polarization
of light by, 195; attempts of, to
polarize heat, 264.

Malta, observations on Saturn's rings
made at, 66.

Manchester, thunderstorm near, in
1835, 292.

Mankind, distinct tribes of, 255;
limited perceptions of, 267.
Marcet, M., rate of increase in tem-
perature below the earth's surface
calculated by, 230.

Marco Polo, atmospheric effects ob-
served by, in ascending mountains,
118.

Marine plants, laws regulating their
distribution, 252, 253; animals,
specific localities of, 254.
Mariner's compass. See Compass.
Mars, used in illustrating the possible
effects of the radial distributing
force, 19; telescopic planets be-
tween Jupiter and, 20, 21; diame-
ter of, 21; mean distance from the
sun,
ib. note; eclipse of Jupiter by,
42; parallax found by observing
his oppositions, parallax of, 53; in-

MEDIUM.

ternal structure, 58; astronomical
tables of, 63; climate of, 225;
approach of the comet of 1770 to,
362; comets having their peri-
helia in his orbit, 381.
Marseilles, transit of a comet across
the sun observed from, 374.
Masses, of the sun, of planets and
their satellites, computations find-
ing, 55, 56.

Mathematics, use of, in the study of
astronomy, 2.

Matter, theory of its constitution,
102; hypotheses as to forces unit-
ing its particles, 103, 104; coun-
terbalancing action of elasticity and
cohesion, 105; crystallization com-
mon to all forms of, 109; indestruc-
tibility of its particles, 110; com-
position of unorganised bodies, sub-
ject to permanent law, 110, 111;
agent composing or decomposing,
112; mode of ascertaining the
magnetism of, 335; increatable,
indestructible, 353; proportion of,
to spare, 424.

Matteucci, M., effect of electricity on
polished silver observed by, 221;
experiment showing polarization by
electricity, 286; doubts of, on the
polarity of diamagnetism, 348 note;
experiments on magnetic action in
crystals, 350; observation on the
action of compression, 352.
Maury, Lieutenant, calms named by,
123.

Measurement of astronomical dis-
tances, formula assisting, 43.
Mechain, M., Encke's comet seen by,365.
Mechanical equivalent of heat, 275.

engines, incapable of generating
force, 279.
Mediterranean, the, conditions of,
shutting out the tidal wave, 98;
hurricane in, divided into two
storms, 126; vegetation of, 252.
Medium, ethereal, transmitting mag-
netism, 344; density of, 356; pro-
bable relations of, to gravity, ib.;
experiment testing its magnetic pro-
perties, 356, 357; functions of,
357; pervading the visible crea-

MEDIUM.

tion, 358; unsolved question
touching, 365; a cause of accele-
rated revolutions of comets, 366,
367; direction of its increase in
density, 367.

• Medium occupying space, 424.
Medusa tribes, the, phosphorescent
brilliancy of, 295.

Megallanic clouds, the, 417, 418.
Melloni, M., experiments of, in pho-
tography, 214; his application of
the principle of thermo-electricity,
333; experiments of, in transmis-
sion of heat, 258-263; fixing the
maximum of heat in the solar spec-
trum, 264; in polarization of heat,
264-266; light separated from
heat by, 265.

Melville Island, height of the ther-
mometer in, in January, 247.
Mercury, inclination of his orbit to
the plane of the ecliptic, 21; eclipse
of, 42; cause of his rotation un-
known, 65; ellipticity of his orbit
compared with the terrestrial, 74;
climate of, 226; comet revolving
between the orbits of Pallas and,
367; attraction of, determining a
comet's orbit, 369; comets revolv-
ing in his orbit, 381; velocity of,
400.

-, propagation of heat in, 273;
rotating by electricity, 314.
Meridian, constant, of high water, 92.

mode of determining the mag-
netic, 343.
Meridians, size and form of the earth
determined from, 46; measurement
of arcs, 47; anomalies from local
attraction, 48; result of the com-
putations, 48, 49; permanent, of
the moon, 69, 70.

-, magnetic, influencing the direc-
tion of metallic veins, 346.
Messier, comet of 1770 observed by,
361;
Encke's comet seen by, 365;
nebula described by, 409.
Metallic salts, action of the rays of
the solar spectrum on, 203.

springs used in construction of
musical instruments, 143; rods
giving musical notes, 144.

MITSCHERLICH.

Metallic surfaces, polarized light re-
flected from, 193; plates, impres-
sions on, from bodies in contact with,
220.
Metals, expansion of, by heat, 271;
propagation of heat in, 274; trans-
mission of electricity by, 284; elec-
tricity developed by oxidation of,
298; determining the appearance
of a spectrum of voltaic flame, 303;
distilled in the voltaic arc, 304,
305; electro-plating of, 309; pro-
perties of, modifying electric suscep-
tibility, 333; magnetism an agent
in the formation of, 346.
Meteor, the bursting of a, 118.
Meteors, 420; theory of, 421-423.
Meteoric stones, proofs of their foreign
origin, 420, 421; shower of, 421,
422.

Mètre, adopted by the French as their
unit of linear measure, 89.
Mica, polarization by induction effected
with, 286.

Milky Way, the, described, 385; Sir

John Herschel's description, 385,
386; "Coal Sacks," 386; stars
composing, 286, 287; zone of stars
crossing, 390; position of variable
stars with regard to, 395; crowd-
ing in, apparent only, 405; orbit
in the plane of, 406; relation of, to
the stellar universe, 407; nebula
resembling, 409; its quarter of the
heavens, 414, 415; dividing the
nebulous system, 416, 417; great
nebula in, 418; remote branches of,
419.

Minerals, possessing the phosphores-
cent property, 294.

Mines, cause of increased temperature
in, 229; green plants growing in,
253.

Mira, periods of its fluctuations in
lustre, 390.

Mirage, supposed cause of, 157.
Miraldi, rotation of Jupiter's satellite
determined by, 70.

Mitscherlich, M., his experiments on
crystals, 107; discoveries, 108; ex-
periments of, in expansions of crys-
tals, 272.

MOCHA.

Mocha, meteors falling at, 421.
Moignot, M., crystals compressed by,

189.
Moisture, an indispensable requisite

for vegetation, 248; transmission
of electricity effected by, 284, 288.
Molecular polarity, produced by elec-
tricity, 282; attraction, electricity
developed by destruction of, 284.

structure affecting transmission
of electricity, 303.

vortices, hypothesis of, account-
ing for the absorption of light.

177.

Molecules, material, attraction and
repulsion of, 103; effect of elasti-
city and cohesion on, 104-106;
uniting to form crystals, 107-109;
extreme minuteness of ultimate,
110; of ether, modes of their vi-
bration in natural and polarized
light, 193; in fluorescent light,
196, 197; images traced by the
mutual action of, 219-222; ar-
rangement of, connected with mag-
netism, 350-352.

Mollusks, distinct species of, 254.
Monocerotis 11, a triple star, 395.
Monsoons, theory of the, 123, 124.
Months, antiquity of, as a measure of
time, 85.

Moon, the, force restraining, 4, 5;
mean distance of, from the earth,
4; results effected by her nearness
to the earth, 7; annual rate of de-
crease in her orbit's excentricity,
17; average distance of, from the
earth's centre, period of her circuit
of the heavens, 34; her periodic
perturbations, 35-38; causes as-
signed for acceleration of her mean
motion, 36, 37; eclipses of, 39,
40; longitudes determined by ob-
servations of, 42, 43; her mean
horizontal parallax, 52; sources
whence her mass may be deter-
mined, 55, 56; her diameter, 56;
rotation of, 68; librations, 69;
mountains, 70; precession result-
ing from her attraction, 79-81;
influence of, producing tides, 91,
92, 96-98; period of her declina-

MUSIC.

tions, 97; atmospheric equilibrium
disturbed by her attraction, 121;
cause of her apparent increased
magnitude in the horizon, 158;
photographic image of, 214; com-
parative amount of light emitted
by, 225; cause of the rarity of
her atmosphere, 226; increased
intensity of light at full, ib. ; effect
of the terrestrial atmosphere on
heat radiated from, 227; cause of
acceleration in the mean motion
of, 366; light reaching the earth
from, 404.

Moorcroft, herbarium collected by,
250, 251.

Moser, Professor, mutual influence of
bodies in contact tested by, 219,

220.

Mossotti, Professor, his analysis to
prove the identity of the cohesive

force with gravitation, 103, 104;,
his definition of gravity, 355.
Motion, a law of the universe, 274;
perpetual, impossible, 279.
Mountains, anomalies in measurement
caused by, 48; rarity of atmo-
sphere on, 118; cause of perpetual
snow, 119; modes of determining
heights of, 120; becoming new
centres of motion in hurricanes,
126; influence of chains on tem-
perature, 241, 242; cause of
éboulemens in, 271; tops of, fused
by lightning, 293.

lunar, effect of solar rays pass-
ing between, in eclipses, 41; in-
fluence of, on the moon's motions,
96; three classes of, 70.
Mu Herculis, direction of solar motion
with regard to, 406.
Multiple systems of stars, 395.
Mundy, Captain, mirage described
by, 157.

Music, comparison instituted of sym-
pathetic notes in, 2; regulated un-
dulations of sound producing, 142;
instruments of, 143; experiments
by means of vibrating plates, 144-
146; sympathetic vibrations, 147,
148; experiments showing, 148,
149.


MUSICAL.

Musical instruments constructed by
Professor Wheatstone, 143.

NAPLES, comet discovered from, 370.
Nautical Almanac, computations for
calculating longitudes, 43; time
calculated by, 84.
Navigation, importance of lunar mo-
tions in, 42; laws of storms to be
observed in, 127, 128.
Neap-tides, 96, 99.

Nebulæ, number and general aspect of,
407; catalogues, 407, 408; classes,
408; irregular, 408, 409; of definite
form, 409; spiral, 409, 410; an-
nular, 410, 411; elliptical, double,
411; distance of a nebulous star
discoverable, 411, 412; aspect and
colour of planetary, 412; elliptical
common, 413; globular clusters,
413-415; resolution of, 415; star
clusters, 415, 416; probable law
of motion, 416; distribution of,
416, 417; the megallanic clouds,
417, 418; round Argus, 418,
419; remote systems, 419; invi-
sible solar, 421; meteors falling
from, 422.

Nebulous appearances of a comet,

364; extent of, matter surround-
ing a comet, 373; its variable
brilliancy, 374; appearances round
the sun, 412.

stars, 411, 412.
Needle, magnetized, effect of Voltaic
electricity on a, 312, 313; sus-
pended by means of electricity,
314; condition of its deviation by
an electric current, 317.
Negative electricity defined, 282;
mode of exciting, 283.

impressions in photography,

204.
Neptune, periodical variations in his
orbit, 22; revolution of his satel-
lite from east to west, 33; re-
moteness of, 54; anticipation of
discovery, 61; orbit and motions
of, determined, 62; his diameter,
mean distance from the sun,
temperature of, 225; action of, on
Halley's comet, 363.

63;

NODES.

Neutral phosphate of soda, its crys-
tals, 109.

New Mexico, monsoons occasioned by
its deserts, 124.

Newton, Sir Isaac, steps of his argu-
ment for the universal influence of
gravitation, 3; his discoveries of
modes of attraction, 4; motions of
bodies projected in space, ascer-
tained by, 5; form of a fluid
mass in rotation ascertained, 45;
problem occupying astronomers
since, 64; discrepancy between his
theory of tides and observations,
96; compound nature of white
light proved by, 159; his analysis
of the solar spectrum disputed,
161; his theory of light disproved,
167; measurements of coloured
rays, 172, 173; scale of colours,
174; decisive experiment disprov-
ing the theory of light, 202; re-
marks on the transmission of
gravity, 355.

Niagara, the falls of, not independent
of the influence of astronomy, 1.
Nickel, sulphate of, change in its
crystals, when exposed to the sun,
107.

Niepce, M., photographic pictures
rendered permanent by, 204; dis-
covery in photography suggested,
207; colours of images of the sun
taken, 213; experiments by, on
saturation of substances with light,
296.

Nismes, discovery of a telescopic
planet at, 21.

Nitrogen, proportion of, in the at-
mosphere, 117; spectrum from,
303; iron volatilized by the Vol-
taic arc in, 304; unaffected by
magnetism, 344.

Nobili, M., direction of electric cur-

rents ascertained by, 333.

Nodes, ascending and descending, of a
planet defined, 9; movement of
their lines in secular disturbances,
14; advance and recession of, 18;
supposed recession of, on the equa-
tor of the solar system, 24; of the
moon, period of their sidereal re-

NON-CONDUCTORS.

volution, 37; secular inequality
affecting, 38; influence of, on
eclipses, 39; cause of their rapid
motion, 55; points of rest on a
vibrating string, 141; in the vi-
brations of an undulating column
of air, 142; in vibrations of solids,
147.

Non-conductors of electricity, 284,

285.

Non-electrics, 285.

North Atlantic, the, winds in, 124,

Polar Ocean, tide in the, 94.
Norway, course of the tidal wave to,

94.

Notes in music, 142, 143.
Nubecula, Major and Minor, 417,
418.

Nucleus, of Halley's comet, changes in
its aspect, 364; disappearance of,
in Encke's, 369; division, in Biela's,
369, 370; diaphanous, 373; so-
lidity of, tested, 374; of a spiral
nebula, 409.
Nuremburg, observations on a comet
from, 370.

Nutations produced by the moon's

nearness to the earth, 7; in Ju-
piter's equator, 29; in the planet-
ary axes, 66; effect of, on the pole
of the equator, longitudes and lati-
tudes altered by, 81.

Nysa, nearness of its orbit to the
earth, 21.

OAKS, range of, near the equator,
250.
Occultation, central, by Halley's
comet, 364; geographical position
ascertained by, 384; prospective,
by a sun of a Centauri, 400.
Occultations of stars, 42, 43.
Ocean, the, density and mean depth

of, 51; mean density, compared
with the earth's, 77; its form in
equilibrio, when revolving round
an axis, 92; solar and lunar attrac-
tion disturbing its equilibrium, ib. ;
inequalities in periodic motions,
93; motions of the tidal wave in,
95; stability of its equilibrium,
100; circulation of currents in,

ORBITS.

ib.; stratum of constant tempera-
ture in, 101; zones of, ib.; de-
crease and increase of temperature
with depth, 231; absorption and
radiation of heat by, 242; electri-
city evolved from, 291."
Oceans of light and heat, processes
producing, 225.

Ochotzk, the sea of, depression of the
barometer observed in, 120.
October, 1832, position of Saturn's
rings in, 67.

Olbers, M., computations for a comet
by, 367; period of his comet,
370; comet of 1811 observed by,
374.

Opaque bodies, mode in which heat is
developed in, 227.

Ophiuchi 70, anomalies in the mo-
tions of, 400.
Ophiuchus, clusters of the Milky Way
between the Shield and, 387; new
star disappearing from, 393.
Optic axis, the, of crystals, 183;
phenomena exhibited by transmis-

sion of a polarized ray along, 187,
188; affected by compression, 189.
Orbit, the, of the earth, attraction
intensified by its diminished ex-
centricity, 37; excentricity of,
affecting temperature, 74, 75;
crossed by comets, 368.

of the moon, force ruling, 4;
its excentricity, 34; changes in,
35; its inclination to the plane of
the ecliptic, 79.

of a nebula, 415.

of the solar system, 405, 406.
Orbits of comets, subject to variation,

361; examples, 361-363; pros-
pective changes in, 369, 370; of
Donati's, 379; forces determining
their forms, 382, 383.

of double stars, 396-400.

of planets, force regulating a
planet's velocity in, 8; measure-
ment of their excentricity, 9; seven
elements of, determining their po-
sition in space, 10; unequal move-
ments in, 15; variation from
elliptical to circular, 17; secular
variations of, in inclination to the

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