Part 55

Oscillations, wide-spreading, produced by gravitation, 2; mechanical principle affecting small, 11; of the sines and cosines of circular arcs, 20; invariable plane whence they may be estimated, 24; of the pendulum retarded, 32; of the pendulum, experiments founded on, 50, 51; experiments testing the earth’s density, 57; a measure of time, 83; produced by tides, 95, 96; instruments measuring atmospheric, 113; barometer affected by periodic atmospheric, 120, 122; of ears of corn, 129, 130; producing musical notes, 140-142; instances of forced sympathetic, 148; causing vicissitudes in climates, 247; of the pendulum, disturbed by effects of temperature, 272; measuring variation of electrical intensity, 287.

Otto, M., motions of the heavenly bodies observed by, 405.

Oxidation of metals, electricity developed by, 298; by the Voltaic discharge on polished silver, 305.

Oxides decomposed by electricity, 307; alkalies resolved into metallic, 307.

Oxygen, in crystals, 109; proportion of, in water and carbonic oxide, 111; in the atmosphere, 117; chemical combination with, evolving light and heat, 270; action of electricity on, 284; electricity afforded by combination of metals with, 298; spectrum from, 303; separated from water by electricity, 307; paramagnetic, 344.

Ozone, produced by electricity, 284.

Pacific Ocean, mean depth of, 77; course of tidal waves down, 93; mean depth of, 96; currents, 100.

Paderborn, fulgorites from, 293.

Pallas, inclination of its orbit to the ecliptic, 10; diameter of, 21; astronomical tables, 63; ellipticity of its orbit compared with the terrestrial, 74; height of its atmosphere, 226; comet revolving between the orbits of Mercury and, 367.

Pan’s pipes, vibrations in the air passing over, 142.

Parabolic motion, ratio of forces procuring, 382.

Parallax of the sun, circumstance favourable to its correction, 21.

—— of an object defined, 43.

——, definition, mode of ascertaining, 52; distances computed from, 52-54; calculation from the moon’s horizontal, 55.

—— of fixed stars, 387-390.

—— of meteors, 421, 422.

Paramagnetic substances, 335, 336.

Paramagnetism defined, 335; substances it is resident in, 336; modes of imparting, _ib._; a dual power, _ib._; imparted by induction, 337; law of its intensity, 338; a property of oxygen, 344; in antithesis to diamagnetism, 347; neutral substances obtained by combinations of diamagnetism and, _ib._; Dr. Tyndall’s experiments on polarity of, 348; dependent on arrangement of molecules, 350, 351; affected by compression, 351; truth establishing its identity with diamagnetism, 356, 357.

Parathermic rays, analyzed by Sir John Herschel, 217-219.

Paris, variation in length of the pendulum at, 51; mean annual temperature, 228; temperature of an Artesian well in, 230.

Paths of comets, 359, 360; secrets disclosed by their excentricities, 365.

Parry, Sir Edward, turned back by the Polar current, 101; mean temperature calculated from observations of, 245; thermometer at Melville Island marked by, 247.

Pauxis, the Straits of, ebb and flow of the sea in, 98.

Peel, Sir William, thunderstorm experienced by, 293, 294.

Pegasus, nebulous region of, 417.

Pendulum, the, principle equalizing its oscillations, 50; the earth’s figure calculated by, 50, 51; experiments ascertaining the earth’s density, 57; isochronous, a measure of time, 83; a standard of the measure of extension, 89; the, a connecting link between time and force, 94; inventions to neutralise the effects of temperature, 272.

Penumbra, in lunar eclipse, breadth of space occupied by, 40.

Perigee, of the lunar orbit, period of its revolution, 37, 38; cause of its rapid motion, 55.

——, solar, periods of its coincidence with the equinoxes, 86.

Perihelion of a planet’s path defined, 16.

—— of the earth’s orbit, its position regulating the length of seasons, 74.

Periodic inequalities of planets, 13, 14; law from which they are deduced, 24, 25; of Jupiter’s satellites, 28, 29; lunar, 35.

Perkins, Mr., experiments of, testing the laws of compression, 78.

Peron, M., specific diversity of marine animals asserted by, 254.

Perpendicular force, the source of periodic inequalities, 15; effects produced by, 18.

Perpetual motion, invariable proportion between heat and force precluding, 279.

Perseus, variable star in, 390, 391.

Peters, Mr., comet discovered by, 370; parallax of α Lyræ, 388, 389; distances of fixed stars calculated, 389; his theory of Sirius’ irregular motions, 392; sun’s motion proved by, 405.

Petit, M., observations of, on meteoric satellites, 423.

Peru, arcs of the meridian measured in, 48.

Phases of the moon, regulating returns of eclipses, 39.

Phenomena, of effects of light in eclipses, 41, 42; applied to computing longitudes, 43; caused by tidal oscillation, 96; from force of cohesion, 106, 107; of capillary attraction, 115; produced by refraction and reflection, 155-157; by polarization of light, 186-190; exhibited in fluorescence of light, 196, 197; resulting from interaction of rays and molecules, analogous to effects of photography, 219-222; phosphorescent, 295, 296; of galvanism, 310; of magnetism, 335, 345-348; magnecrystallic, 349, 350; exhibited by comets, 363, 364, 369, 370, 372-376; by the Milky Way, 385-387; by variable stars, 390-393; by double stars, 397-401; by nebulæ, 409-415, 417-419; by meteoric showers, 421, 422.

Phosphorescence, rays of the solar spectrum exciting, 216; cause of, in the solar spectrum, 217; excited by electricity, 294; fish possessing the property of, 295; the glow discharge, 295, 296; experiments investigating the nature of, 296.

Photo-galvanic engraving, 309.

Photography, first suggestions, 203; discoveries and improvements in, 204-207; conditions affecting the chemical properties of rays producing, 207, 208; images of the solar spectrum obtained by, 208-210; coloured copy of an engraving, 211; phenomena in, suggesting an absorptive action in the solar atmosphere, 212, 213; chemical energy producing, distinct from light and heat, 214; experiments by means of, testing the properties of rays, 218, 219; experiments on action of light, heat, electricity, producing results analogous to effects of, 219-223.

Photosphere, the, of the sun described, 224.

Physical Sciences, the most extensive example of their connection, mode of its operation, 1.

Pi Herculis, direction of solar motion with regard to, 406.

Pisces, nebulous region of, 417.

Planetary motion, representation of, 14.

—— nebulæ, 409; appearance of, 412.

Planets, paths round the sun described by, 5; law determining their revolutions, _ib._; forces adjusting their forms, 6; their motions in elliptical orbits, mean distance from the sun, 8; mode of obtaining the place of, in their orbits, 9; computations giving the place of, in space, 10; disturbances from reciprocal attraction affecting, compensations, 13-19; telescopic, 20, 21; perturbations in the mean motions of, 25, 26; influence of, on lunar motions, 36; eclipses and conjunctions of, 42; formula finding their masses, 55; their diameters, 56; mass of the telescopic, compared with the moon, _ib._; comparative density, 58; method of computing their places, 58-64; discovery of, 61-63; exploded theory touching telescopic, 63; periods of their rotations, 66; variation and position of the plane of the ecliptic produced by, 79; its effect on the equinoctial points, 80; climates of, 225, 226; probably magnets, 346; constant velocity of their mean motions, 366.

Plants, distribution of known species over the globe, 249, 250.

Plates, vibrating, experiments by means of, 144-146.

Plateau, M., experiments of, on colour, 165, 166.

Platina, incandescent, used as a source of heat, 260.

Platinum, experiment producing spontaneous combustion of, 112, 113.

Playfair, Professor, quoted in reference to La Grange’s discovery, 23.

Pleiades, the, nebulous stars, 415.

Plücker, Professor, discoveries of, in the action of magnetism in crystals, 349.

Plumb-line, deviations of, from local attraction, 48; earth’s density calculated from a deviation of, 58.

Poinsot, M., La Place’s discovery extended by, 23; comparison by, 24.

Point, ready escape of electricity from a, 288.

Poisson, M., decisions of, on the phenomena of capillary attraction, 114.

Polar basin, probable temperature of, 245, 246.

—— star, change of position in the, 81, 82.

—— vegetation, contrasted with tropical, 248.

Polarity, produced by electricity, 282; of magnets defined, 336; induced in iron, 337; its antithetical manifestations of, 339; invariably dual, 341; of diamagnetic substances, 347, 348.

Polarization of light, definition of, 179; refracted by various substances, 180-183; by reflection, 184; angles of, 185; phenomena exhibited by transmission through analyzing media, 186-188; circular, 189-191; theory of circular and elliptical, 192, 193; substances producing, 193, 194; theory of coloured images formed by, 194; accidental, 195; discovery of, _ib._; degraded light incapable of, 198; communicating electricity, 220; plane of motion of vibrations in, 223.

Polarization of heat, first attempts, 264; successful experiments, 265-267.

—— of electricity by induction, 286.

——, experiment showing the action of magnetism on, 319; affected by mechanical compression, 352.

Poldice mine, the, temperature of the water pumped from, 229.

Poles, the, cause of the flattening of a spheroidal mass at, 6; diameter of Jupiter at, 27; experiment determining the increase of gravitation towards, 49, 50; the, drifting of ice from, 100, 101; of maximum cold, centres of the isothermal lines, 245, 246; nature of magnetic force distinguished by, 332; four terrestrial, of maximum magnetic force, two magnetic, 343.

Pollux, an optically double star, 401.

Port Bowen Harbour, transmission of sound across, when frozen, 136.

Positive electricity, defined, 282; mode of exciting, 283.

—— impressions in photography, 204.

Pouillet, M., his estimate of the mean temperature of space, 119; quantity of solar heat received by the earth computed by, 238; data furnished by, to Professor Thomson, 279; development of electricity investigated by, 291.

Powell, Baden, substances producing elliptical polarization enumerated by, 193; dispersion of light accounted for by the undulatory theory, 200, 201; experiments in transmission of radiant heat, 262; attempts to polarise heat, 264.

Power, Mr., undulations producing fluorescent light computed by, 197; law of solar rays acting on media, 198.

Præsepe, the, in Cancer, 415.

Precession, a, in the equinoxes of planets, its cause, 66; mean, of the equinoctial points, defined and calculated, 80; influence of, on the pole of the equator, on longitudes, 81.

Pressure, electricity elicited by, 283, 284; law of electrical, 288.

Principato Citeriore, earthquake in, 234.

Prisms, solar spectrum formed by, 159; neutralizing effects of colour, 164; of brown tourmaline, light polarized by, 180; resolution of the pure white sunbeam by, 222; substance of, determining the point of maximum heat in the solar spectrum, 263, 264; electrical light analysed by, 288.

Problem determining the motions of translation of the celestial bodies, 11; of the three bodies, 58; the hardest astronomical, 92.

Procyon, light of, 402.

Proportion, definite, the law of, in mixing substances, 111, 112.

Protoxides of metals, their crystals, 109.

Prussia, Eastern, fulgorites from, 293.

Ptolemy, decrease in the inclination of Jupiter’s orbit since the age of, 19; discovery of the Evection by, 35; Indian lunar tables calculated in his time, 88; horoscope ascribed to the age of, 89; effects of refraction observed by, 155; colour of Sirius in his time, 401.

Quadratures, the equation of the centre in, 9; lunar orbit augmented in, 35; tides affected by the moon in, 96.

Quadrupeds, distribution of distinct species of, 255.

Quartz, crystallised, light polarized circularly by, 189, 190; varieties of polarization exhibited by, 193.

Quebec, extremes of temperature found in, 247.

Quinine, sulphate of, producing fluorescence of light, 197.

Radial force producing periodical changes in relative positions of the heavenly bodies, 15; effects produced by, 16, 17; principle neutralising its ultimate result, 19, 20.

Radiation of heat, laws regulating, 257; universal from substances, 268; natural phenomena resulting from, 269; slow decrease of the earth’s central heat from, 232; influence of, on temperature, 239; power of, in water compared with dry land, 242; of heat, a transfer of motion, 277.

Radii vectores, signification of, 8; areas described by, 10; force disturbing in the direction of, 14, 15.

Ragona-Scina, M., his theory of rayless lines in the spectrum, 163.

Rain, force shaping drops, 106; cause of periodic tropical, 123; region of, 124; theory of its formation, 270; an electric conductor, 292.

Rankine, Mr., his theory of the structure of matter, 104; his theory of the absorption of light, 177.

Rays, common nature and common properties of, 268.

—— of heat, existing independently of luminous, 257; laws of transmission of, 258; analogy between transmission of luminous rays and, 259; temperature of their source affecting transmission, 260; varying in nature with their origin, 261; transmitted through coloured glass, 262; traversing various media, _ib._; subject to refraction and reflection, 263; polarized, 265-267; absorption and reflection of, 268; rotation of polarized, caused by magnetism, 319.

—— of light, bent by passing from rare into dense media, 153; partial and total reflection of, 156; loss of, by obliquity of incidence, 158; theory of their transmission and absorption, 159-161; comparative refrangibility of, 163; experiments on dispersion of, 164; principle determining their colour, 170, 171; transmission of, in glass or water, 177, 178; conditions of polarized, 179; double refraction, 181-183; polarized by reflection, 184, 185; coloured images produced by interference of, 194, 195; internal dispersion of, 195-198; heat, light, chemical action, independent properties of, 214, 215; undulations constituting, 223; conditions modifying the power of solar, to produce heat, 237; transmitted independently of calorific rays, 258; magnetizing of polarized, 318, 319.

Rays, solar, effect produced by their refraction in lunar eclipse, 40; passing between lunar mountains in solar eclipse, 41.

—— of the solar spectrum, their chemical properties, 203; varying chemical energy, 207, 208; varying nature of their action, 208; peculiar chemical action of the red, 209-211; deoxydating and oxydating action of, 211, 212; experiments detailed, 212-215; new, obscure, detected by Sir John Herschel, 217.

Red Sea, the, tide in, 98.

Reflection of waves of sound, 137, 138; of rays at surfaces of strata differing in density, phenomena occasioned by, 156, 157; affecting colour, 160; motion of a ray of light in, 177; light polarized by, 184, 185; elliptical polarization produced by, 193; heat polarized by, 266; of radiant heat from surfaces, 268.

Refraction of the sun’s rays in lunar eclipses, 40; of waves of sound, 138; of light by the atmosphere, 153, 154; mode of estimating, in case of celestial bodies, 155; formulæ obtaining in case of terrestrial objects, _ib._; phenomena occasioned by, 155, 156; colours decomposed by, 159, 160; produced without colour, 164, 165; power of, in media affecting the elasticity of the luminous ether, 177; of a polarized ray, 180; double, 181, 182; Fresnel’s theory of, 183; diminished capability of producing fluorescence, 196; capability of, in rays, affecting their chemical action, 209-212; effect of, on the lunar atmosphere, 226; influence of, on transmission of heat, 258; of rays of heat, 261-264; heat polarized by, 266.

Refrangibility, substances diminishing, of light, 196; affecting the chemical action of rays, 209-212; affecting radiation of heat, 257; affecting transmission of radiant heat, 261-263.

Reich, Professor, temperature of mines observed by, 228; mean increase calculated by, 230.

Reptiles, distribution of distinct species of, 254.

Repulsion of electricities, 283; experiments determining the laws of electrical, 286, 287; modes of, in static and in Voltaic electricity, 317; developing comets’ tails, 375-377.

Resistance, a cause of accelerated motion, 367.

Retina, the, action of, in receiving impressions, 166; comparative sensibility of its fibres to light, 178.

Retrograde motion of comets, 359, 368, 373, 379.

Rhodiola rosea, identical species of, found in Tartary and in Scotland, 251.

Rhombohedrons of carbonate of lime, 109.

Richman, Professor, killed by lightning, 293.

Richter, variation in length of the pendulum observed by, 51.

Rings of Saturn, 66-68; Saturn’s, diamagnetic, 347; luminous, surrounding comets, 374, 375; surrounding Donati’s, 379.

Ritchie, Professor, electrical experiments of, 314.

Ritter, M., chemical properties of the solar spectrum observed by, 203; oxydizing effect of red rays, 209.

Rive, M. Auguste de la, rate of increase of temperature in wells observed by, 230.

Rivers, curvature of the land proved by, 46; influence of, on the earth’s rotation, 71; rising of tides in, 98; effect of, in cooling the atmosphere, 243.

Roget, Dr., phenomena of electro-magnetism explained by, 313.

Rome, observations on lunar mountains made at, 70; era fixed at, 85; comet discovered from, 370.

Ross, Sir James, stratum in the ocean discovered by, 101; depressure of the barometer observed by, 120; volcanic region discovered, 232.

Rosse, Lord, nebulæ resolved by his telescope, 407, 408; spiral nebula, 409, 410; annular nebulæ discovered by, 410; nebulous star, 411; planetary nebulæ, 412; nebulæ resolved by, 415.

Rotation affecting winds, 122-127; of winds, 124, 125; of hurricanes, 125, 126; produced by the Voltaic current acting on iron, 305; of stratifications of electrical light, 307; caused by electricity, 313, 314; of light caused by an electric current, 319; of magnets producing electricity, 330-332; changes produced in comets by, 376.

Rotations of the solar system, 7; of the sun, 65; of the planets, 66; of satellites, 68; of Jupiter’s satellites, 70; of the earth, a measure of time, 71; influence of temperature on, 72; axis of, invariable, 76, 77.

Rotatory motion, form indicating, 65; of Donati’s comet, 379.

Roux, M. le, observations on magnetic action in crystals, 350.

Rudberg, M., refrangibility of substances ascertained by, 201, 202.

Ruhmkorff, M., improvements on his electro-inductive apparatus, 328.

Russell, Scott, Mr., velocity of the tidal wave estimated by, 95.

Russia, arc of the meridian measured in, 48; climates of, 244.

Sabine, General, variations in the magnetic elements investigated by, 343, 344.

Sagittarius, comet traversing the constellation of, 379; the Milky Way in, 386; nebula, 414.

Sahara, the, causing monsoons, 124.

—— desert, extent, influence of, on the atmosphere, 243.

Salt, Mr., papyrus sent from Egypt by, 89.

Sand, tubes in, formed by lightning, 293.

Sandy deserts influencing temperature, 243.

Sandwich Land, excess of cold in, over corresponding latitudes, 241.

Sargassa, or grassy sea, found in the Atlantic, 253.

Satellites, intensified action of attraction upon, 7; intimate union of, with their primaries, 26; exceptions to a general law of the solar system, 65, _note_; rotations equal to the times of their revolutions, 68; comet passing through, 69.

——, Jupiter’s, proportion of their mass to that of their primary, 27; disturbing force of attraction affecting their orbits, 28; periodic and secular inequalities, 28, 29; eclipses, 30; rotation, 70; passage of a comet through, 359; comet nearly approaching, 370.

—— of Saturn, 32; of Uranus and Neptune, 33.

——, mode of computing their masses, 55; comparative density of, 58.

—— of Neptune, 63.

—— of the earth, shooting stars, 423.

Saturn, unequally occurring compensations of disturbance in its motions, 15; disturbing influence of, on Jupiter, excentricity of its orbit compared with Jupiter’s, 17; retarding the revolution of Jupiter’s nodes, 19; invariable plane passing between Jupiter and, 24; observations on the mean motions of Jupiter and, 25, 26; eclipse of, 42; internal structure, 58; astronomical tables of, 60; period of his year, 66; the rings of, described, 66-68; his ring probably diamagnetic, 347; action of, on Halley’s comet, 362, 363; comets having their perihelia in his orbit, 381.

Saurian reptiles, distinct tribes of, 254.

Saussure, M., temperature of mines observed by, 228, 229; lichen discovered by, 249.

Savart, M., his researches and experiments in acoustics, 132, 133; experiments on vibrations of glass rulers, 145-147; experiments showing sympathetic undulations, 148, 149; discoveries on the nature of voice, 152.

Savary, M., orbital elements of a double star determined by, 396; his mode of ascertaining the actual distances of fixed stars, 402, 403.

Scheele, M., chemical changes effected by the solar spectrum observed by, 203.

Schroëter, height of planetary atmospheres calculated by, 226.

Schwabe, M., periodic variation in the solar spots observed by, 344.

Science, its value regarded as the pursuit of truth, 1; errors of the senses corrected by, 32; evidence of its antiquity, 87.

Sciences, mutual relations of forces proving the connexion between, 319-321; analysis proving the whole circle of, kin, 427, 428.

Scoresby, Captain, phenomenon occasioned by refraction observed by, 156.

Scorpio, vacant patch of the Milky Way in, 386; position of, 390; a double star in, 395; nebula in, 414.

Scotland, progress of the tidal wave round, 94.

Sea, the, inappreciable influence of, on the direction of gravity, 77; mean height of snow-line above the level of, 241; comparative extent of, 242.

Seasons, conditions determining the duration of, 74; cause of their unequal periods, 87; theory of the tropical dry and rainy, 123.

Seaweeds, photographic impressions of, 205, 206; luxuriance, deep colours of, 253.

Secchi, Professor, mountains of the moon observed by, 70; photographic image of the moon obtained, 214; temperatures of the sun’s surface estimated, 225; experiments of, in photographing the moon and Jupiter, 226, 227.

Secular inequalities of planets, 13, 14; means of discovering, 24, 25; effect of, on the mean motion of the moon, 36, 37.

—— variations in mean values of the magnetic elements, 343.

Seebeck, point of maximum heat in solar spectrum fixed by, 263; discovery of, 264; relations of heat to electricity discovered by, 332, 333.

Seed-lobes, proportion in the distribution of plants having one or two, 252.

Seleniate of zinc, crystals of, 107.

Senarmont, M., experiments of, in expansion of crystals, 273.

Senses, necessarily inaccurate testimony of the, 281.

September, times coinciding in, 84.