HOROLOGIUM.

Horologium, nebulous patches in, 417.
Horton coal-mine, experiments with
the pendulum in, 57.
Hours, cause of their mal-correspond-
ence over the globe, 86.
Hudson's Bay, tide in, 98.
Humboldt, his sufferings from rarity
of the atmosphere, 118; his expla-
nation of the apparent greater
acuteness of hearing observed at
night, 135; observations of, in
mines, 228; causes of disturbance
in the equal diffusion of heat enu-
merated by, 240; identical produc-
tions of the Old and New World
found by, 251; his distribution of
palms and grasses, 252; green
plants found growing in mines by,

253.

Hunt, Mr., coloured image of the
solar spectrum obtained by, 209;
image obtained in England, 213;
his experiments in tracing images
by juxtaposition of bodies, 220,
221; experiments on the condensing
power of rays, 223.

Hurricanes, origin and cause of, 125,

126; curve described by the axis of,
ib.; their extent and velocity, 126,
127; phenomena resulting from
their revolving motion, 127; laws
of, making avoidance possible, 128.
Huygens, theory originated by, 169.
Hydrogen, proportion of, in water and

gases, 111; spectrum from, 303;
separated from water by electricity,
307.

Hygrometer, dew-point measured by,
269.

Hyperbolic motion, ratio of forces pro-
curing, 382.

IAPETUS, seen by Mr. Lassell, 33.
Ibn Junis, progress of science in his
time, 90.

Ice, formation of, 271; force acting
in its formation, 276; stopping the
current of voltaic electricity, 309.
Icebergs, drifting of, 100, 101; far-
thest range of northern and southern,
241; effect of electricity in colli-
sions, 284.

IOTA.

Iceland spar, its property of double
refraction, 181; polarized ray ana-
lyzed by, 187; transmission of ra-
diant heat by, 258; electricity
elicited from, 284.
Illumination, comparative, of objects,
experiments determining, 227.
Images, coloured, of the solar spec-
trum, 208-211; traced by contact
and juxtaposition of bodies, 219,
220; by electricity, 221; by media
absorbing hot rays, 222.

India, arcs of the meridian measured
in, 48; discovery of Saturn's ring,
66; ancient monument of astro-
nomical knowledge, 85; observa-
tions confirming the antiquity of
astronomical science in, 88.
Indian Ocean, the tidal wave in, 94;
monsoons blowing over, 124.
Induction, law of, in electricity, 285,
286; magnetic, 314, 315; phe-
nomena of, produced by electric
currents, 324; illustrated by the
Atlantic telegraph, 325, 326; ve-
locity of electricity modified by
power of, 327; possibility of electro,
furnishing a motive power, 328; of
electricity by rotation of magnets,
330-332; as possessed by magnets,
336; paramagnetism evolved by,
337; means of accelerating, ib.;
subject to the laws of mechanics,
338; analogy between electric and
magnetic, 341; of heavenly bodies,
affecting terrestrial magnetism, 346,
347; diamagnetic substances ca-
pable of, 348.

Indus, comet passing through the con-
stellation of, 379.
Inequality, the, of Jupiter and Saturn

marking historical epochs, 88.
Insects, law of their dispersion, 255.
Instruments, musical, 143, 149, 150;
imitating articulation of letters,
151, 152.

Insulation in electricity, 285.
Interference, laws of, neutralizing un-

dulations, 138, 139; the theory of,
referred to a general law, 169.
Iota Cetæ, comet observed near, 372.

Orionis, a nebulous star, 411.

IRELAND.

Ireland, progress of the tidal wave
towards, 94.
Iron, distilled, 305; rotation of its
particles, ib.; magnetized by elec-
tricity, 314, 315; magnetic pro-
perties of, 332; rendered paramag-
netic, 336, 337; magnetic and
electric properties of, 347; elasticity
of, affected by magnetism, 352.
Islands, character of their floras, 252.
Isogeothermal lines of temperature

defined, 238, 239; parallel with
the isothermal lines, 246.
Isomorphous crystals, 109.
Isothermal lines of temperature de-

fined, 240; latitudes of, deviation
from the line of the equator, 245;
formula determining, 246; simi-
larity of vegetation in the same,

253.

Italy, local attraction, occasioning in-
accuracy in measurement, 48.
Ivory, M., his method of computing
heights, 120; his theoretical inves-
tigation of planet forms, 44; deduc-
tion from measurement of arcs of
the meridian, 48.

JACOB, Mr., discovery of Saturn's
ring by, 66; periodic time of a
Centauri determined by, 399; pe-
riodic time of 70 Ophiuchi, 400.
James, Colonel, measurements of, in
the General Survey of Great Britain,
47; density of the earth determined
by, 58.

Jamin, M., remarks of, on substances
producing elliptical polarization, 193.
January, epoch of its beginning the
year, 85.

Jews, denominations of time in their
calendars, 85.
Josephstadt, discovery of a comet
from, 367.

Joule, Mr., heat considered a mecha-

nical force by, 275; his view of
elastic force, 276; amount of latent
force in a pound of coal, computed
by, 278; furnishing data to Pro-
fessor Thomson, 279; quantity of
heat generated in a unit of time by
electricity computed by,302; power-

JUPITER.

ful magnet obtained by electricity,
315; electric machines constructed
by, 328; experiments proving heat
and mechanical power convertible,

329.

Jovial system, mass of the whole, 55.
Julian Calendar, year of, the first of
our era, 86.

June, 1833, reappearance of Saturn's
rings, 67; coincidence of times in,

84.

Juno, the diameter of, 56; astronc-
mical tables of, 63.

Jupiter, rotation of, distinguished from
the other planets, 7; periodical
inequality in his motions, 15; dis-
covery of telescopic planets between
Mars and, 20, 21; diameter of, 21;
his position with respect to the
equator of the solar system, 24;
inequalities in the motion of, appa-
rently anomalous, 25, 26; his
mass proved not homogeneous,
29; eclipses, 30, 31; compres-
sion of his spheroid computed,
39; eclipsed by Mars, 42; mass of,
compared with the sun, 55; his
diameter, 56; increase of density
in, 58; astronomical tables of, 60;
rapid rotation, 66; period of a year
in, ib.; effect of his disturbing
energy, 81; photographic images
of, 226; light reflected by his at-
mosphere, 227; action of, on the
comet of 1770, 361, 362; on Hal-
ley's comet, 362, 363; comet e-
volving between the orbits of the
earth and, 367; future influence of,
on comets, 369; comet nearly ap-
proaching his fourth satellite, 370;
comets having their perihelia in his
orbit, 381.

KANE.

KANE, Dr., Polar Sea discovered by,
94; cold of Northern Greenland
marked by, 247.

Kappa Crucis, cluster of coloured stars
round, 419.

Draconis, seen in the pole of the
equator, 88, 89.

Karsten, Mr., impressions made on
glass by electricity, 221.
Kasan, summer and winter mean tem-
perature of, compared with Edin-
burgh, 246, 247.

Kater, Captain, approximate length of
the pendulum, determined by, 89.
Kempelen, M., speaking-machine in-
vented by, 151.
Kepler, paths, revolutions of planets
discovered by, 5; his law regarding
the mean distances of planets from
the sun, 19; law of, applied to cal-
culating distances, 53, 54; rapidity
of planetary revolutions determined
by his law, 66; his law finding
areas described by heavenly bodies,
referred to, 360.

Kew, balloon ascent from, 119.
Knoblauch, position of the magne-

crystallic axis proved by, 349.
Knowledge, limited nature of human, 2.
Kotzebue, stratum in the ocean dis-
covered by, 101.
Kratzenstein, M., instrument invented

by, articulating words, 151.
Kupffer, M., observations of, on tem-
perature, 246.

LA BASILICATA, earthquake in, 234.
La Grange, his investigations into the
stability of the solar system, 20,
21; greatest discovery of, 23.
La Hire, phases in comets observed
by, 380.

La Place, stability of the solar system
proved by, 20; principle in astro-
nomical calculations established,
23; angle of inclination fixed,
24; his theory accounting for ac-
celeration in the moon's mean mo-
tion, 36, 37; result of observations
compared with his theory of Ju-
piter's satellites, 55; theory of
planetary motion, 65, 66; universal

LATITUDE.

epoch proposed by, 87; scientific
observations complementing his-
torical records, 87; date fixed by,
for the lunar tables of the Indians,
88; justifies Newton's theory of
tides, 96; density of a liquid column
estimated by, 114; action of the
earth on a comet, 359; change in a
comet's orbit, 361; cause of error
in Clairaut's calculation pointed out
by, 363; opinion of, as to the comet
of 1682, 378.

"Lake of the Gazelles" ascribed to an
effect of reflection, 157.

Lalande, epochs of conjunctions com-
puted by, 42.

Lambda Herculis, general motion of
the stars determined by, 405.
Land, dry, comparative extent of, on

the globe, 242, 244; extent of, in
diametrical opposition, 244.
Landscapes in chiaroscuro, produced
by photography, 207.
Languages, resemblances and analogies
between, 255, 256.

Lapland, arcs of the meridian measured
in, 48; transit of Venus observed
in, 53.

Laroche, M., his experiments on trans-

mission of radiant heat, 259, 261.
Lassell, Mr., satellite of Saturn dis-
covered by, 32; observations of, on
Uranus' satellites, 33; his discovery
of Neptune's satellite, ib.; observa-
tions on Saturn's rings, 66.
Latent heat, energetic action of, or
matter, 275-277.

Latitude, the, of a planet defined,
mode of obtaining, 9, 10; cause of
periodical inequalities in, 15; per-
turbations from action of the per-
pendicular force, 18; moon's mo-
tion in, disturbed, 35; effects of
disturbance, 38; data of, used in
computing a planet's place in the
heavens, 58-60; conditions ensuring
the invariability of geographical,
76, 77; change effected by nutation
in, 81; climate not invariable in
the same, 239; degrees of, where
diminution of mean heat is most
rapid, 244, 245; the same mean

LAYANG.

temperature in different, 246, 247;
of wine-growing, 250; magnetic
storms varying with, 345.
Layang, observations made at, 1100
years before the Christian era, 88.
Le Sueur, specific diversity of marine

animals observed by, 254.
Le Verrier, M., principle of La
Grange applied by, 21; zone of in-
stability found, ib.; discovery of
Neptune, 62; his observations on
atmospheric waves, 122; comets
identified by, 362; his table of
comets' orbits, ib.

Lecaille, his globular nebulous cluster,
414; nebula, 418.
Lenticular nebulæ, 409; haze sur-
rounding the sun, 412.
Leo, nebulous system in, 417.
Leon-Faucault, M., velocity of light
in air and water ascertained by,
202.

Lerius, banks of algae found by, 253.
Leslie, Professor, compression of air
calculated by, 78; experiments on
radiation of heat, 257.

Lexel, observations of, on the comet
of 1770, 361, 362.

Libra, the five great planets in con-

42.

junction near,
Librations of the moon, of Jupiter's

satellites, 69; of a Centauri, 399.
Lichen, red, growing on snow, 249.
Light, rate of its velocity, 31; truth

deduced from the uniformity of its
velocity, 32; from the aberration
of, ib.; period required to reach the
earth from a Centauri, 54; action
of the atmosphere on, 153; con-
ditions regulating the transmission
and reflection of, 156; loss of,
transmitted by the horizontal stra-
tum, 157; effects of transmission
through the atmosphere, 158; New-
ton's analysis of, 159; Brewster's,
161; phenomena disproving New-
ton's theory, 167, 168; undulatory
theory, 168-170; conditions af-
fecting its intensity and colour,
170; experiments testing the mu-
tual relations of colour and, 171-
175; law of its absorption identical

LIQUIDS.

with a law of motion, 175-177;
repeated vibrations producing the
sensation of, 178; polarized, de-
fined, 179; modes of polarization,
substances polarizing, 179-185; ac-
cidental polarization of, 195; de-
graded, or fluorescence, 196; objec-
tions to the undulatory theory
analyzed and disproved, 199-202;
comparative velocity of, in air and
water, 202; pictures produced by
reflected, 203-207; rays of, inde-
pendent of heat, 214, 215; com-
parative amounts of solar and lunar,
225; different measures of illumina-
tion from, 227; influence of, on
vegetation, 249; colour developed
without the influence of, 253; se-
parated from heat by Melloni, 265;
produced by accumulation of heat,
270; law regulating the force of
artificial, 279, 280; electrical, 288,
289; produced by voltaic electri-
city, 302; stratifications of the
electric, 306; influence of mag-
netism and electricity on, 319, 320;
of comets, 379-381; of the fixed
stars, 401-404.
Lightning, development of heat ex-
hibited by, 276, 277; experiment
showing the velocity of, 289;
theory of, 292; the back stroke, ib.;
force of the direct stroke, 293;
sheet, 294; effect of, on the com-
pass, 312.
Lime, carbonate of, variety of form
in its crystals, 107; invariable form
ultimately assumed by, 109.
Lines of magnetic force, 338, 339;
experiment ascertaining the form of,
339, 340; terrestrial, 341, 342;
extensive courses of, 344; a con-
nected system, 345; diamagnetic,
348.

Lion, the, conjunction of planets in,
42.

Liquids, balance of forces constituting,

104, 105; action of capillary at-
traction on, 113-116.

possessing the property of cir-
cular polarization of light, 190,
191-193.

LIQUIDS.

Liquids, conditions affecting the trans-
mission of radiant heat by, 263;
evaporation from, 269; expansion
of, by heat, 271; propagation of
heat in, 273; action of heat as a
mechanical force on, 275-277.
London, retarding of the tidal wave
between Aberdeen and, 94.

-, pendulum vibrating in its lati-
tude, a standard of measurement,
89; fulgorites exhibited in, 293.
Long, Dr., his attempt to measure
distances of fixed stars, 388.
Longitude, mode of reckoning mean
and true, 9; of the perihelion and
of the epoch defined, 10; cause of
periodical perturbations in, 14;
calculation from the moon's influ-
ence on the sun's, 55; data of, used
in computing a planet's place in
the heavens, 58-60; change effected
by precession and nutation in,

81.

Lloyd, experiments of, in polarization
of heat, 264.

Lubbock, Sir John, theory of plane-
tary motion completed by, 64; his
theory of shooting stars, 423.
Lumière cendré, definition of, 227.
Lunar distance, defined, 43.

theory, mean distances obtained
from, 43.

tides of the terrestrial atmos-
phere, 121.

Lundahles, M., motions of heavenly

bodies investigated by, 405.
Lupus, position of, 390.

Lussac, Gay, M., uniting of gases by
volumes discovered by, 111; ascent
of, in a balloon, 118; course of
a lightning flash ascertained by,

292.

Lutetia, diameter of, 56.

Lyell, Sir Charles, his theory of
changes of temperature in the
northern hemisphere, 75; annual
number of volcanic eruptions com-
puted by, 233; volcanic pheno-
mena related by, 234.
Lyncis 12, a triple star, 395.
Lyra, a variable star in, 391; a
double star, 395; nebula, 410.

MAGNETO.
MACHINERY, relations of, to force,
353.

Mackintosh, Sir James, quotation from,
illustrating the essential advantages
of study, 1.

Maclear, Mr., parallax calculated by,
387.

Madeira, vegetation of, 252.

Madras, Saturn's ring discovered from,
66.
Magnecrystallic action, 349; tem-
perature affecting, 352.

Magnetic bodies, difference in power
of, 347.

elements, the three terrestrial,

343.

equator of the earth, 343.
meridian, the, mean action of
forces determining, 343.

poles of the earth, 343.

storms, 344; varying with lati-
tude, 345, 346.

Magnetism, source of, 318; producing
electrical phenomena, 322, 323;
rotatory motion a source of, 330;
classification of substances, with
regard to their susceptibility of,
332; residing in substances after
two manners, 335; experiment il-
lustrating the forces of, 338; anti-
thesis, its general character, 339;
form of its lines of force, 339, 340;
analogous properties of electricity
and of, 340, 341; terrestrial, 342-
347; connexion between solar and
terrestrial, 344; action of, in
crystals, 349-351; influence of
temperature in, 352; affecting elas-
ticity of matter, 352, 353; a pro-
perty of the ethereal medium (?),
356, 357.

―, electro, discovery, importance of

the science, 312; rotation effected
by, 313, 314; electric intensity
measured, 315; action of currents
in, defined, 316; Ampère's theory
of, 317, 318; causing rotation of
polarized rays, 319; action of,
on light, 320; accidental combina-
tions, 342; influencing metallifer-
ous deposits, 346.
Magneto-electricity, principle suggest-