Part 53

—— Sagittarii, cluster of the Milky Way round, 387.

—— Virginis, eclipse in, 397; orbit of the revolving star determined, 398.

Ganges, the, tidal wave at the mouths of, 94.

Gardner, Mr., extent of diametrically opposite lands estimated by, 244.

Gases, conditions retaining matter in the form of, 104, 105; combinations of, 111; transmission of radiant heat through, 258; expansion of, 271; voltaic spectrum modified by, 303; effect of heat on the conducting powers of, 309.

Gassiot, Mr., experiments of, on the electric discharge, 306; connexion between magnetism and light discovered by, 321; electric apparatus improved, 328.

Geneva, the Lake of, experiment on the velocity of sound in, 135.

Gensanne, M., increasing temperature of mines tested by, 228.

Geographers, lunar motions important to, 42.

Geological changes, probable cause of, 77.

Geology, the lessons of, 326.

Georgia Island, S., excess of cold in, over corresponding latitudes, 241.

Germany, shooting stars seen from, 421.

Gibraltar, the Straits of, turning aside the tidal wave, 98.

Giromagny, temperature of the lead-mines of, 228.

Glass, effect of cohesion on plates of, 106; musical notes elicited from rods and plates of, 144-147; transmission of waves of light in, 177; polarizing light, 184, 185; elliptical polarization produced by, 193, 194; used in photography, 207; impressions on, from bodies in contact with, 220; impressions on, traced by electricity, 221; transmission of radiant heat by, 259; by coloured, 261, 262; its temper altered by magnetism, 352, 353.

Globular clusters of nebulæ, 413-415.

Glow-discharge observed by Captain Bonnycastle, 295, 296.

Gold, action of, on light, 173.

Good Hope, the Cape of, icebergs drifted to, 101.

Goodricke, Mr., variable stars discovered by, 391; opaque bodies represented as revolving round fixed stars by, 394.

Graham, Mrs., account of an earthquake by, 234.

Graham’s compensation pendulum, 272.

Gravitating force of the sun, 365, 424, 425.

Gravitation, offices of, in the material creation, 1, 2; process of reasoning in ascertaining the law of, 3; law determining its intensity in the solar system, 5; complex action of, by attraction in mass and in particles, 6; increase of, towards the poles of the earth, 45; calculations founded on its increase, 49-51; in a mine, its excess over surface, 57; action of, modifying tides, 92, 93; law, universally acting on matter, 105; the air subject to, 117; influence of, in motions of the heavenly bodies, 382, 383; double stars revolving by, 398; stellar systems subject to, 400; influence of, on nebulæ, 416; a general law of the visible creation, 424; mode of its action, 425, 426.

Gravity, centre of, in spheres, effect of impulses passing through, 7; of the solar system, invariable plane passing through, 23; straight line described by, 24; action of, in determining the figure of the earth, 44, 45; definition irreconcilable with the conservation of force, 354, 355; question of its transmission, 355, 356.

Great Bear, the nebulous zone passing, 416.

—— Gobi, the, effect of the expansion of air over, 124.

Greeks, astronomical observations of, confirming results of analysis, 38.

Greenland, ocean on the northern coast of, 94.

Greenwich, lunar distances computed for, 43; quadrant of the meridian passing through, furnishing a unit of linear measure, 89; periodic circuits of winds, 125.

Grimaldi, coloured fringes bordering shadows described by, 175.

Groombridge, velocity of his proper motion, 404.

Grotthus, the transmission of voltaic electricity investigated by, 298.

Grove, Mr., copper and zinc plates electrified by, 220; substances radiating heat of different refrangibilities enumerated by, 257; the transmission of voltaic electricity investigated by, 298; electric heat tested by, 301, 302; remarks of, on carbon, 302, 303; on the voltaic arc, 304, 305; remarks of, on light and heat, 319; electric apparatus improved by, 328; his definition of the ethereal medium, 355.

Grylli, supposed delicate sense of hearing in, 132.

Guanaxato, temperature of the silver-mine of, 228.

Gulfs separating stars, 390.

Gum-guaiacum, chemically affected by rays of the solar spectrum, 203; condition of its sensibility to light, 206; effect of red rays on, 209; used in experiments on parathermic rays, 217, 218.

Gum-lac, electrical intensity measured by means of, 286, 287.

Gymnotus electricus, the, 310.

Haidinger, M., experiments of, proving water an essential part of crystals, 107.

Hail, formation of, 270.

Hales, his calculation of the amount of surface exposed by the leaves of a helianthus, 243.

Hall, Mr., achromatic telescope constructed by, 165.

Halley, elements of a comet’s orbit computed by, 362; return of his comet, 363; changes in its aspect, 363, 364; records of, 365; no solid nucleus in, 374; cause of its luminous sectors, 376; Sir John Herschel’s observations on, 378.

Hare, the, comet observed near, 372, 373.

Harmonics of the fundamental note in music, 140, 141.

Harmony, property of sound regulating, 131; definition of, vibrations producing, 142.

Harris, Sir William Snow, experiments of, in electricity, 287, 288; lightning-conductors invented by, 293.

Harrison, pendulum invented by, 272.

Hastings, coast of France distinctly seen from, 157.

Heat affecting the form of crystals, 107; evolved in chemical combinations, 110; irregular decrease of, in the atmosphere, 119; maxima of, in the solar spectrum, 215; peculiar chemical quality of, in parathermic rays, 218; impressions traced by, 220-222; periodical variations in the sun’s, 225; different proportions of solar, reaching the planets, 225, 226; effect of the terrestrial atmosphere on lunar, 227; mode of its development in opaque bodies, _ib._; sources of terrestrial, 228-238; irregular distribution of, 239-247; laws affecting its radiation, 257; its transmission, 258-262; polarization of, 264-267; undulatory theory, 267; absorption and reflection of radiant, 268; phenomena caused by radiation of, 269; accumulation of, producing light, 270; expansive force of, 271, 272; modes of propagation, 273, 274; produced by motion and equivalent to it, 274-277; laws regulating the force of artificial, 279, 280; power evolved by application of, 280; identical in nature with sound, 281; electrical, 288; sheet-lightning caused by, 294; phosphorescence, 294; developed by voltaic electricity, 301, 302; effect of, on electrical conductors, 309; connexion between the production of electricity and, 310; its direct relation to magnetism and electricity, 319, 320; mechanical power and convertible forces, 329; terrestrial magnetism attributed to the action of, 333; measured by electric currents, 334; affecting atmospheric magnetism, 344; fundamental principle of the dynamic theory, 357.

Helena, St., distinct flora of, 252.

Helix, circular and elliptical, described in polarization of light, 192, 193; electrical experiments by means of, 314; induction of, increasing electric power, 322, 323.

Heller, his observations on the comet of 1556, 370, 371.

Helmholtz, Professor, power of chemical force estimated by, 112; his calculation of the chemical force developed by combustion, 278; of the amount of latent force in our system, 280.

Hemisphere, cause of excess of cold in the southern, 241; superficial extent of land in northern and southern, 244.

Henley, Mr., magneto-electric machine constructed by, 325.

Henderson, Professor, parallax of α Centauri calculated by, 387; of Sirius, 389.

Henry, Professor, experiments of, on magnetism, 315.

Herapath, Mr., his view of elastic force preferred to Sir Humphry Davy’s, 276.

Hercules, eclipse of a double star in, 398; globular nebulous cluster, 414.

Herschel, Sir William, observations of Saturn’s and Uranus’s satellites by, 32, 33; theory of, regarding the solar constitution, 41; cause of effects of light in eclipses according to, 42; rotation of Jupiter’s satellites determined by, 70; mutual independence of light and heat, 214, 215; influence of the sun’s spots on heat, 225; point of maximum heat in the solar spectrum, 263; comet of 1811 observed by, 374; its luminous envelopes examined, 375; the Milky Way examined by, 385; his discovery of the orbital motions of double stars, 388; catalogue of double stars by, 395, 396; periodic time of γ Virginis determined by, 398; eclipse of a double star observed, _ib._; binary system discovered, 400; remarks on the motions of the stars, 405; nebulæ resolvable into stars, 507.

Herschel, Sir John, approximate periods of satellites ascertained by, 33; thickness of Saturn’s ring computed, 67; observations of, on seasons, 74; difficulty of varying time, in observations at distances, obviated by, 86; tenuity of atmospheric air demonstrated, 110; rapid decrease of density in the atmosphere, 118; mean temperature of space computed by, 119; height of Etna measured, 120; his explanation of anomalies in atmospheric phenomena, _ib._; quotation from, on the transmission of sound, 136; observations of, on thunder, 138; remarks on the absorption of light by coloured media, 175, 176; on polarization of light, 179; experimentalising apparatus, 188; discovery of epipolic light, 197; discoveries in photography, 205, 206; analysis of the solar spectrum, discovery of its chemical properties, 207-219; his theory of volcanic action, 235-237; observations showing the maximum of heating influence of the solar rays, 238; theory of the original distribution of plants, 254; divergent flame of a comet observed by, 364; remarks on the possible destruction of the solar system, 372; causes assigned by, for contraction of diameter in comets, 378; comparative lustre of stars measured by, 384, 385; the Milky Way described, 385, 386; number of stars in a group of the Milky Way computed, 387; variable star discovered, 391; remarks of, on the nature of the fixed stars, 392; variable stars discovered by, 393; remarks on variable stars, 394; star missed by, 395; double stars discovered, 396; eclipse of a double star observed, 397; orbits determined, 398, 399; observations on colours of double stars, 401; light of α Centauri compared with the moon’s by, 404; light of the fixed stars calculated, _ib._; observations on nebulæ corrected, 407; catalogues of nebulæ, 408; nebulæ discovered by, 409; annular nebula described, 410; magnitude of planetary nebulæ computed, 412; globular nebulous cluster described, 413; law of gravitation ascribed to nebulæ, 416; nebula round η Argus described, 418; his work on Nebulæ, 419.

Herschel, Miss, Encke’s comet seen by, 365; catalogue of nebulæ, 407.

Hevelius, divergent flames of a comet described by, 364; contraction in diameter of comets observed, 377; phases in comets observed, 380.

Hieroglyphics interpreted by astronomy, 89.

Himalaya, the, inappreciable effect of, on the globe’s surface, 6; singular effect of refraction on, 156; cause of greater elevation of the snow-line on the northern side of, 241; flora of, 250.

Hind, Mr., comet’s orbit computed by, 370, 371; observations of, on Donati’s comet, 379; variable stars discovered by, 391; vanishing star discovered, 393; his belief in planetary systems, 394.

Hindostan, the tidal wave striking on its coasts, 94.

Hipparchus, precession discovered by, change of seasons since his age, 80; phenomenon suggesting his catalogue of the stars, 392.

History corroborated and corrected by astronomy, 87, 89.

Hoar-frost, cause of, 269.

Holtzmann, M., opinion of, with regard to the vibrations of polarized light, 223.

Hoogly, the, bore of, 94.

Horizon, effects produced by the denser stratum of air in, 157, 158.

Horologium, nebulous patches in, 417.

Horton coal-mine, experiments with the pendulum in, 57.

Hours, cause of their mal-correspondence over the globe, 86.

Hudson’s Bay, tide in, 98.

Humboldt, his sufferings from rarity of the atmosphere, 118; his explanation 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 enumerated by, 240; identical productions 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 procuring, 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; farthest range of northern and southern, 241; effect of electricity in collisions, 284.

Iceland spar, its property of double refraction, 181; polarized ray analyzed by, 187; transmission of radiant heat by, 258; electricity elicited from, 284.

Illumination, comparative, of objects, experiments determining, 227.

Images, coloured, of the solar spectrum, 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 astronomical knowledge, 85; observations 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; phenomena of, produced by electric currents, 324; illustrated by the Atlantic telegraph, 325, 326; velocity 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 capable of, 348.

Indus, comet passing through the constellation 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 undulations, 138, 139; the theory of, referred to a general law, 169.

Iota Cetæ, comet observed near, 372.

—— Orionis, a nebulous star, 411.

Ireland, progress of the tidal wave towards, 94.

Iron, distilled, 305; rotation of its particles, _ib._; magnetized by electricity, 314, 315; magnetic properties of, 332; rendered paramagnetic, 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 defined, 240; latitudes of, deviation from the line of the equator, 245; formula determining, 246; similarity of vegetation in the same, 253.

Italy, local attraction, occasioning inaccuracy in measurement, 48.

Ivory, M., his method of computing heights, 120; his theoretical investigation of planet forms, 44; deduction from measurement of arcs of the meridian, 48.

Jacob, Mr., discovery of Saturn’s ring by, 66; periodic time of α Centauri determined by, 399; periodic 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 mechanical force by, 275; his view of elastic force, 276; amount of latent force in a pound of coal, computed by, 278; furnishing data to Professor Thomson, 279; quantity of heat generated in a unit of time by electricity computed by, 302; powerful 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; astronomical tables of, 63.

Jupiter, rotation of, distinguished from the other planets, 7; periodical inequality in his motions, 15; discovery 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, apparently anomalous, 25, 26; his mass proved not homogeneous, 29; eclipses, 30, 31; compression 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 atmosphere, 227; action of, on the comet of 1770, 361, 362; on Halley’s comet, 362, 363; comet revolving between the orbits of the earth and, 367; future influence of, on comets, 369; comet nearly approaching his fourth satellite, 370; comets having their perihelia in his orbit, 381.

——, orbit of, revolutions of its major axis, source of variation in excentricity, 17; slow revolution of its nodes, decrease in its inclination to the ecliptic, 19.

—— with his satellites, an epitome of the solar system, 27; effect of his excessive equatorial diameter on their orbits, 28; satellites, libration in, 69; rotation of, 70.

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 temperature of, compared with Edinburgh, 246, 247.

Kater, Captain, approximate length of the pendulum, determined by, 89.

Kempelen, M., speaking-machine invented 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 calculating 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 magnecrystallic axis proved by, 349.

Knowledge, limited nature of human, 2.

Kotzebue, stratum in the ocean discovered by, 101.

Kratzenstein, M., instrument invented by, articulating words, 151.

Kupffer, M., observations of, on temperature, 246.

La Basilicata, earthquake in, 234.

Lacaille, his globular nebulous cluster, 414; nebula, 418.

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 astronomical calculations established, 23; angle of inclination fixed, 24; his theory accounting for acceleration in the moon’s mean motion, 36, 37; result of observations compared with his theory of Jupiter’s satellites, 55; theory of planetary motion, 65, 66; universal epoch proposed by, 87; scientific observations complementing historical 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 computed 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 transmission of radiant heat, 259, 261.

Lassell, Mr., satellite of Saturn discovered by, 32; observations of, on Uranus’ satellites, 33; his discovery of Neptune’s satellite, _ib._; observations on Saturn’s rings, 66.

Latent heat, energetic action of, on matter, 275-277.

Latitude, the, of a planet defined, mode of obtaining, 9, 10; cause of periodical inequalities in, 15; perturbations from action of the perpendicular force, 18; moon’s motion 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 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 instability found, _ib._; discovery of Neptune, 62; his observations on atmospheric waves, 122; comets identified by, 362; his table of comets’ orbits, _ib._

Lenticular nebulæ, 409; haze surrounding the sun, 412.

Leo, nebulous system in, 417.

Léon-Faucault, M., velocity of light in air and water ascertained by, 202.

Lerius, banks of algæ 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 conjunction near, 42.

Librations of the moon, of Jupiter’s satellites, 69; of α Centauri, 399.

Lichen, red, growing on snow, 249.