Part 51

Antinous, comet observed in the constellation of, 372; the Milky Way between Orion and, 386.

Antithesis, the general character of magnetism, 339.

Aphelion of a planet’s path defined, 16.

Apogee, solar, its coincidence with the solstices, 86, 87.

April, 1833, disappearance of Saturn’s rings, 67; apparent and mean time coinciding in, 84.

Apsides of an axis defined, 9; direct, variable motion of, 14; cause of their advance, or recession, 16.

Apures, the mission of the, Humboldt’s observations on sound at, 135.

Aqueous vapour, proportion of, in the atmosphere, 117.

Ara, nebula in, 414.

Arabian Gulf, the, monsoons blowing over, 124.

Arabs, the, their observations on planetary irregularities, 26; lunar eclipses observed by, 38; their division of time, 85; the pendulum used as a measure of time by, 90.

Arago, François, experiment by, in proof of the undulatory theory of light, 200; decisive experiment suggested by, 202; observations in photography, 213; observations on the moon’s atmosphere, 226; increase of temperature below the earth’s surface calculated by, 230; slow communication of temperature from the earth, observed, 244; source of magnetism discovered, 330; theory of his magnetic experiments, 332; divergent flames of a comet described by, 364; his treatise on comets, 368; nature of comet’s light determined by, 380, 381; numbers of comets computed, 381, 382; remark of, on _fixed_ stars, 405.

Arc, the Voltaic, 303-305.

Arcet, M. d’, vibration of fibres of the retina according to, 178.

Archer, Scott, stimulus given to photography by, 207.

Arcs of the meridian, mode of measuring, 47.

Arctic Sea, depth of the zone of constant temperature, 101.

—— regions, vegetation found in, 249.

Arcturus, comet bearing comparison with, 379; rank of, 384.

Areas, described by the radii vectores of planets, a test of disturbing forces, 10; unequable description of, 15.

Argelander, M., period of a comet calculated by, 370; his mode of estimating distance of fixed stars, 389; periods of fluctuation in stars computed by, 390, 391; sun’s motion proved, 405.

Argentine preparations in photography, chemical energy varying with, 207, 208; changes effected by washing with alkalies, 210, 211.

Argo, variable star in, 393.

Aries, season of the sun’s entrance into, in Hipparchus’ age, 80.

Arseniate of soda, its crystals, 109.

Artesian wells, mode of sinking, origin of the name, 230.

Asia, indigenous productions of, 249.

Assyrians, the, division of time by, 85.

Astronomers, fruits of their labours, 3; question still to be resolved by, 24; terrestrial orbit differently measured by, 36.

Astronomical distances, method of measuring, 43; tables, method of forming, 58-64.

Astronomy, its rank in the physical sciences, an important office of, 1; studies necessary to the study of, 2; the key to divers problems in physical science, 3; the two greatest discoveries in, 23; the three departments of, 58; standards for measurement afforded by, 83; application of, to chronology, 87-89; furnishing standards of weights and measures, 89, 90; atmospheric effects connecting the laws of molecular attraction with, 102; progress lately made by, 419, 420.

Atalanta, diameter of, 56.

Atlantic Ocean, direction of tidal waves in, 93; conditions modifying tides, 94; depth of, 96; currents, 100; origin of hurricanes, 126; superficial temperature of, 244; distinct vegetation of the polar basin, 252; beds of algæ in, 253; meteors falling in, 421.

—— telegraph, 325, 326; terrestrial magnetism disturbing, 346.

Atmosphere of nebulous stars, 411, 412.

—— of planets, 226, 227.

—— of the sun, its constitution, 42; indications of an absorptive surrounding the luminous, 213; the true, 224.

—— terrestrial, solar rays bent by, in lunar eclipses, 40; influence of, in solar eclipses, 41; its analysis, pressure on the surface of the globe, 117; form of, gradual decrease in density of its strata, 117, 118; influence of temperature on its density, 119; mean pressure of, variable, 120; the medium conveying sound, 129; sympathetic vibrations transmitted by, 147, 148; its action on light, falsifying vision, 153; phenomena produced by accidental changes in its strata, 155-156; effects of increased density in the stratum in the horizon, 157, 158; lunar heat absorbed by, 227; cause of the cooler air in higher regions of, 240, 241; sun’s heat modified by, 244; action of electricity in, 284; transmission of electricity by induction, 286; periodical variations of electricity in, 291; accidental developments of electricity, 291, 292; cause of variations in its magnetism, 344, 345; nebulous bodies made visible by, 421-423.

Atmospheric air, extreme elasticity of, 105.

—— pressure, effect of, on electricity, 288.

Atomic constitution determining crystalline forms, 109.

Atoms, qualities of, determining the nature of substances, 110; differences in weight of, 111.

Attraction, modes of, in spheres, in the celestial bodies, 4; determining the forms of planets, 6; determining the motions of planets, 7; solar, compelling the elliptical revolutions of planets, 8; mutual, of planets, complicating their motions, 10; interference of, disturbing the motions of heavenly bodies, 11; disturbances from the operation of reciprocal, 13; disturbances from inequality of, 14; of satellites to primaries, little disturbed, 26; disturbing force of, in spheroids, 27; its effects on Jupiter’s satellites, 28; sun’s, of the moon, 34; principle modifying the earth’s, 37; local, affecting the plumb-line, 48; comparative force of the sun’s, 57; of an external body affecting a spheroid, 79; producing tides, 91, 92; of particles of matter, 103; capillary, 113; producing annual atmospheric undulations, 121; the lunar atmosphere affected by, 226; expansive force of heat overcoming, 271; of electricities, 283; destruction of, producing electricity, 284; laws of electrical, 286-288; modes of, in static and in voltaic electricity, 317; action of planetary, on comet’s orbits, 361-363; range of solar, 365.

Aurora, the, affecting the compass, 312.

Australia, evidence of deserts in the interior of, 124; species of plants common to Europe and, 251.

Auvergne, temperature of hot springs in, 231.

Axes, change in form of masses revolving round, 6.

——, major, length of, in orbits, invariable, 20; of the orbits of Jupiter’s satellites, cause of the direct motion observed in, 28; position of, in the solar system, 65; a nutation in planetary, 66; of the moon, 68, 69; mechanical law affecting, 76.

——, optic, of crystals, 183.

Axis, greater, of the earth’s orbit, period of its revolution, 38; period of the earth’s revolution, 58; excess of Jupiter’s equatorial over his polar, 66; of rotation, proof of its being invariable, 76, 77.

——, major, of a planet’s orbit, distance from the sun measured by, 8; designation of its extremities, 9; length of, determining the form of the orbit, 10; periods of its revolutions, 17; length of, not permanently changed, 20; Jupiter’s periodically diminished, Saturn’s increased, 26; of the solar ellipse, period of its revolution, 86.

——, magnecrystallic, 349.

Azores, the, icebergs reaching, 100.

Babbage, Charles, his theory of volcanic action, 235-237; quotation from, on the nature of force, 353.

Babinet, M., his theory of dark lines observed in the solar spectrum, 163; comet’s light computed by, 359.

Babylon, eclipse observed at, 36.

Bacon, Francis, anticipation of discovery by, 32.

Baily, Mr., compression of the terrestrial spheroid calculated by, 50; density of the earth determined, 57; fictitious antiquity ascribed to Indian astronomical observations, 88.

Bali, volcanic eruption in, 233.

Balloon, rarity of the air felt in a, 118; observations made from, 119.

Baltic, the, a tideless sea, 98; decreased atmospheric pressure on the shores of, 120.

Barlow, Mr., observations supporting his theory of electric currents, 346.

Barometer, the, principles of cohesion and attraction applied to the construction of, 113; density of the atmosphere measured by, 117; mean heights of, varying with atmospheric densities, 118; mountain heights measured by, 119, 120; atmospheric phenomena affecting, 120; used to trace the course of atmospheric waves, 121; cause of sudden fall in, before hurricanes, 127; refraction varying with, 154.

Barrow, Cape, observations on magnetic storms at, 345, 346.

Battery, voltaic, construction of, 298, 299; Professor Daniell’s improvements, 299, 300; action of, charged with water, 300; constant flow of electricity obtained by means of, 312.

——, magnetic, constructed by Dr. Faraday, 324, 325; Mr. Henley’s magneto-electric, 325; Atlantic telegraph, 326; structure of, for land telegraphs, 328; relation of heat to power of, 329; thermo-electric, 333.

Batsha, port of, tides neutralised in, 99.

Bayle, comparative density of the atmosphere in interplanetary space according to his law, 356.

Bear, Little, the, the polar star in, 82.

Becquerel, M. E., unexplained photographic phenomenon observed by, 213; phosphorescent property in the solar spectrum discovered, 216; cause of phosphorescence, 217; electricity excited by pressure, 283; light attributed to electricity by, 284; cause of phosphorescence investigated, 296; instrument comparing intensities of electricities invented, 300; crystals formed by agency of electricity, 308; thermo-electric battery constructed by, 333; effect of atmospheric on terrestrial magnetism estimated, 345.

Beehive, the, a nebulous star, 415.

Berard, M., experiments of, in polarizing heat, 264.

Berlin, line of coincidence in temperature passing through, 238.

Berne, increasing temperature of a deserted mine in, 230.

Berre, Dr., photographic pictures perfected by, 205.

Bessel, M., his calculations from measurements of arcs of the meridian, 48; calculation of the sun’s mean apparent diameter, 56; his computation of the mass of Saturn’s ring, 68; diminished obliquity of the ecliptic observed by, 81; parallax calculated, 389; his theory of Sirius’s irregular motions, 392; catalogue of double stars, 396; mass of 61 Cygni found by, 404.

Beta Lyræ, a variable star, 391; nebula between γ Lyræ and, 410.

Benzenberg, M., velocities of falling stars computed by, 423.

Biela, M., date of the discovery of his comet, 367; possibility of collision with the earth, 368; present and prospective planetary influence on, 369; becoming two distinct bodies, 369, 370.

Binary systems of stars, 395-406. _See_ Double stars.

Biot, M., his ascent in a balloon, 118; experiments of, on the transmission of sounds through pipes, 137; liquids possessing the power of circular polarization discovered by, 190; his theory of circular polarization, 191; cause of phosphorescence in the solar spectrum investigated by, 217.

Birds, distribution of distinct species of, 255.

Birt, Mr., atmospheric waves measured by, 121, 122.

Bise, in Switzerland, cause of, 242.

Bismuth, its magnetic and electric properties, 347.

Black Sea, the, scarcely affected by tides, 98.

Bode, Baron, law of, assumed in computing Neptune’s position, 61; failing in the case of Neptune, 63.

Bond, Mr., satellite of Saturn discovered by, 32; elliptical nebula resolved, 413.

Bonnycastle, Captain, phosphorescent phenomenon observed by, 295, 296.

Bonpland, M., identical productions of the Old and New World found by, 251.

Boötes, nebulous system in, 417.

Bore, the, of the Hoogly, its origin, 94.

Botanical districts, distinct, of the globe, 251, 252.

Botto, M., thermo-electricity used in decomposition by, 333.

Bouguer, degrees of the meridian measured by, 48.

Boussingault, M., depth of the underground stratum of constant heat calculated by, 228.

Bouvard, M., atmospheric undulations estimated by, 121.

Bradley, Dr., motion of the pole of the equator discovered by, 84; his tables of refraction, 155.

Brahmins, measurement of time by, 85.

Brand, M., observation of, on meteors, 423.

Brewster, Sir David, his analysis of the solar spectrum, 161; experiments on rayless lines, 163; experiments on spectra of flames, 164; law discovered by, determining angles of polarization for light, 183; experiments on fluorescence of light, 197; line of coincidence in temperature of springs and of the atmosphere determined by, 238; temperature of a pole of maximum cold determined, 245; isogeothermal lines determined by, 246; observations on the light of fixed stars, 402.

Brighton, phenomenon caused by reflection observed from, 157.

Brinkley, Bishop, mass of the moon determined by, 56.

British Channel, height of tides in, 98.

—— Isles, atmospheric wave passing over, 121.

Brorsen, M., periods of comets discovered by, 370.

Brown, Dr. Robert, peculiar vegetation found by, in Australia, 251.

Buchan, Dr., phenomenon caused by reflection observed by, 157.

Cæsar, Julius, era computed from his reign, 85.

Cagniard de la Tour, M., instrument designed by, measuring musical notes, 143.

Calms produced by the trade-winds, 122, 123.

Calorific rays. _See_ Rays of heat.

Calotype, the invention of, 204.

Camelopard, nebulous system in, 417.

Canaries, the, vegetation of, 252.

Canary-glass, fluorescence of light in, 196.

Cancer, the calms of, 123; the tropic of, marking the limit of the trade-winds, 126; nebulous cluster in, 415.

Canis Major, position of, 390.

—— Venatica, nebulous system in, 417.

Capillarity, theory of, 113; forces producing, 114; familiar examples of, 115; curious phenomena, 115, 116.

Capricorn, the calms of, 123; the tropic of, hurricanes changing their direction at, 126.

Carbon, its powers contrasted as a crystal and as an opaque amorphous substance, 302, 303.

Carbonate of lime. _See_ Lime.

Carbonic oxide, its constituent parts, 111.

—— acid, proportion of, in the atmosphere, 117.

Cardinal points, the, position of continental masses with regard to, influencing temperature, 244.

Caribbean Islands, hurricanes beginning at, 126.

Castor, discovered by Sir William Herschel, 396.

Cassiopeia, star appearing and vanishing in, 392, 393.

Categat, the, consequence of its narrowness, 98.

Cauchy, M., data furnished by, for investigation of the theory of light, 201.

Cayenne, variation in length of the pendulum between Paris and, 51.

Celestial bodies: law of their mutual attraction, 4; of the solar system: law determining their attraction to the sun, 5; problem to fix the positions of, on occurrence of disturbance in their motions through counteracting attractions, 11; theory of their mutual connection and dependence, 24; mode of finding the absolute distances of, 43; distances of, computed from their parallax, 52, 54; apparent position of, affected by refraction, 153, 154; apparent infinity of, 420.

Centaur, position of, 390; brilliant double star in, 399.

Central Asia, the mountains of, their ascent by Marco Polo, 118.

Centre of gravity. _See_ Gravity.

Centrifugal force, moon’s motions modified by, 5; influence of, on planet-forms, 6; retarding oscillations of the pendulum, 32; action of, in determining the figure of the earth, 44, 45; measurement of its intensity, 49; resolved into two forces, its action on the sea, 100.

Ceres, astronomical tables of, 63; height of her atmosphere, 226; comet of 1770 revolving beyond the orbit of, 361.

Cetus, nebulous patches crossing, 417.

Chaldeans, the, mean longitude found from observations of, 36; result of comparison of their observations with modern, 38.

Challis, Professor, Brewster’s analysis of light questioned by, 161.

Charcoal, light produced by electricity from, 302-303.

Charles V., the Emperor, observations on comets, made in his reign, 370.

Chaudes Aigues, temperature of, 231.

Chemical action of rays of the solar spectrum, 203, 207; varying maximum of energy, 208; action varying with refrangibility, 209-212; action in luminous spectrum not continuous, 213; energy an independent property of rays, 214; properties of the parathermic rays, 219; action of light maintaining vegetation, 249; affinities the source of the power of steam, 278; of electricity on oxygen, 284; eliciting voltaic electricity, 297, 300; voltaic electricity, an agent in, analysis, 307, 308.

—— combinations, theory of, 110; invariable proportions of, 111; cohesive force inducing, 112; producing combustion, 270.

—— force, the power of, 112.

—— rays, causing the deposition of dew, 269.

Chile, elevation of land by an earthquake in, 234.

China, distinct flora of, 251.

—— Sea, the, monsoons blowing over, 124.

—— ink, polarized light reflected from, 193.

Chinese, the, observations of, on the mean motions of Jupiter and Saturn, 25; proof of their early study of astronomy, 88; decimal divisions used by, 90; elements of comets computed from their observation, 365; comet of 1264 recorded by, 370.

—— Tartary, herbarium collected in, 250, 251.

Chladni, discovery of, in musical science, 145.

Christian era, traces of astronomical records before, 365.

Chromatype, the invention of, 206.

Chronology, dependent on astronomy, 87-89.

Chrysotype, the, coloured photographs obtained from, 206.

Circuit, galvanic, modes of obtaining, 332.

Circular arcs, principle with regard to their sines and cosines, a pledge for the stability of the solar system, 20.

—— motion, ratio of forces procuring, 382.

—— orbits of planets distinguished from elliptical, 8; of satellites, 27.

—— polarization of light, 189-192; of heat, 266.

Circumference of the earth, 49.

Civil time, measure of its periods, 83; not precisely adjusted to solar revolutions, 85.

Clairaut, periodic time of Halley’s comet computed by, 362, 363.

Cleavages of crystals, 109; position of, affecting the intensity of magnetic action, 350.

Climates, planetary, 225, 226; cause of the different terrestrial, 237; phenomena affecting, 239, 240; causes of variety of, 243, 244; milder, of the Polar Ocean, 245, 246; like mean annual temperatures not ensuring like, 246; compensations of irregularities, 247.

Clocks, showing apparent sidereal time, 83; regulated to show decimal time, 84; irregular action of, corrected by the laws of unequal expansion, 272.

Clouds, circling the belt of equatorial calms, 123; region of, 124; electricity evolved from, 291-292.

Cloyne, Bishop of, his calculation of the moon’s mass, 56.

Coal-measures, tropical plants in, 72, 73; age of their formation, 75.

Coal, chemical force evolved from, by combustion, 278; source of its combustible qualities, 279, 280.

“Coal Sacks” in the Milky Way, 386.

Cohesion, influence of, on matter, 105; phenomena arising from its force, 106; attraction of, overcome by the expansive power of heat, 271.

Cohesive force, properties of material molecules constituting, 103; effectual only to unite particles of like nature, 110; inducing chemical combination, 112; capillary attraction, an action of, 113.

Coins, impressions taken from, by contact, 220; by electricity, 221.

Cold, contraction caused by, 271, 272; mitigated by slow propagation of heat in air, 273; generated by voltaic electricity, 302; increasing the conducting power of the air, 345.

Colladon, M., experiments of, testing the velocity of sound, 135.

Collision between the earth and comets, possibilities, possible effects of, 367, 369.

Collodion, sensitiveness of, to light, 203; properties of, as an agent in photography, 207.

Colours, seven primary, 159; theory of the decomposition of white light into, 160; degree of refrangibility not invariable, 161; three primary, _ib._; new, discovered by Sir John Herschel, 162; rays refracted without, 164; rarely homogeneous, 165; experiments on accidental and complementary, 165, 166; determined by undulations of ether, experiments, 170-175; of material substances, whence derived, 175; produced by analyzing polarized light, 186-188; varying with refrangibility of rays, 198; obtained in photography, 206; images of the solar spectrum imitating the prismatic, 208-209; of seaweeds, 253; not invariably dependent on light, _ib._; affected by absorption and reflection, 268; of the electric spark, affected by the atmosphere, 289; of the voltaic spectrum, 303; of the electric spark, 304; produced by oxidation on silver, 305; of the fixed stars, 401, 402; of planetary nebulæ, 412; of nebulous clusters, 415.

Columbus, beds of algæ found by, 253.

Column, capillary, forces producing changes in its form, 114, 115.

Coma Berenices, a nebulous cluster, 415; nebulous zone passing, 416, 417.

Combustion, cause of, 270; defined, 304.

Comets, attraction by the sun of, 5; disturbances in the motion of, a key to the nature of the ethereal medium, 22; retrograde motion in, 33; passing through Jupiter’s satellites, 69; return of, to their perihelia, furnishing historical data, 88; existence of the luminous ether demonstrated by, 168, 169; terrestrial atmosphere unaffected by, 358; amount of their light computed, 358, 359; passages of, through the solar system, 359; velocity, paths of, 359, 360; proof of the return of, 360; disturbing action of planets on their orbits, 361; of 1770, an example, 361, 362; computed return of Halley’s, 362, 363; aspects, records of Halley’s, 363-365; discoveries made by the revolutions of, 365; of the solar system, Encke’s, 365, 366; Biela’s, possibility of collision with, 367, 370; periods of various, 370; cause of their brilliancy, 371; velocity, sun’s influence on, 371, 372; of 1843, 372, 373; their constitution, 373, 374; of 1811, its luminous envelopes, 374, 375; sudden convulsions in, 375; tails, 375-377; causes assigned for contraction of diameter in, 377, 378; Donati’s, 378, 379; nature of their light, 379-381; computations of their numbers, 381, 382; orbits of, 383; nebula resembling, 413.

Compass, mariner’s, phenomena disturbing, 312; intensity of a galvanic current measured by, 315.

Compression of the terrestrial spheroid, calculations of, 48-51; cause of the great, in Jupiter, 66; measures of, from pressure of superincumbent mass, 78; effect of, on magnetic action, 351.

Concord, a, in music, 142.

Conductors of electricity, 284, 285; lightning, 293; molecular structure determining the power of, 303.

Conic sections, conditions compelling bodies in space to move in, 5; principle determining their nature, 11.

Constellations, nearest the sun, 390; where the orbit of the solar system lies, 406; occupied by the nebulous system, 417.

Contraction caused by cold, 271, 272.

Cook, Captain, object of his first voyage, 53.

Cooper, Mr., list of missing stars drawn up by, 395.

Copper, electricity communicated to plates of, 220; lightning-conductors of, 293; action of an electro-magnet on, 351, 352.

Cordier, temperature of mines observed by, 228.

Cordilleras, effect on temperature of their table-lands, 241.

Corn, a, field used to illustrate the propagation of sound, 129, 130.

Cornwall, hot-springs in mines of, 229.

Corona Australis, nebula in, 414.

Corpuscular theory of light, 167; phenomena disproving, 171, 175, 176.