Chapter XLVI: Section XXXVII (6)

Trade winds, friction of, not affecting the earth’s velocity, 72;
action on the general motion of the sea, 100;
system of, accounting for atmospheric anomalies, 120;
theory of their origin, phenomena connected with, 122, 123;
becoming monsoons, 124.

Transits of Venus, 52, 53.

——, two consecutive, of any star, a measure of time, 83.

Transmission of radiant heat, 258, 262;
of electricity, 284, 285;
of voltaic electricity, 298;
molecular structure affecting, 303;
method of, determining the influence of electric currents, 317;
of gravity, an unsolved question, 355;
probable agent, 356;
medium of, in space, 424.

Transparent bodies, temperature of, unaffected by the sun’s rays, 227.

Trees, number of species of forest, found in America and Europe, 252.

Tribes, apparently distinct, of the human race, 255.

Triple stars, 395;
periods of revolution in, 400.

Tropical year, change in its length, 80;
period of, 83;
difficulty of adjusting its estimation, 85.

—— revolution of the major axis of the solar ellipse, its period, 86.

—— vegetation, the luxuriance of, 248.

Tuileries, clock in the, showing decimal time, 84.

Twilight, caused by refraction, 154;
effect of reflection, 158.

Tyndall, Professor, his experiments proving diamagnetic polarity, 348;
on magnetic action in crystals, 349.

Undulations, theory of, 99;
of the atmosphere, 121, 122;
of the waves of sound, 129, 130;
intervals produced by interference, 139;
giving musical notes, 142, 143;
sympathetic, 147, 149;
of the luminous ether, 169, 170;
in refraction and reflection, 177;
producing fluorescence, 197;
different, in light and sound, 199, 200;
constituting a sunbeam, 223;
heat propagated by, 267;
of light, evolution of latent force in extinguished, 279, 280;
of natural forces identical, 281.

Undulatory theory of light, 168-170;
law of motion affecting, 176, 177;
phenomena proving, 198;
objection, from the different action of light and sound, refuted,
199;
proving the existence of the ethereal medium, 358;
acceleration in comet’s motion proving, 367.

—— theory, experiments determining in favour of, 200, 201;
final and decisive experiment, 202;
of heat, 267.

Unison, note in, 142.

United States, astronomical observations made in, 371, 373.

Uranium, phosphorescent property of, 296;
peculiar luminous properties of, 296.

Uranus, effect of reciprocal attraction between Neptune and, 22;
periods of the revolutions of his satellites, 33;
distance from the sun, 54;
astronomical tables of, 60;
discovery suggested by his perturbations, 61;
observations on, leading to Neptune’s discovery, 62;
sun’s influence in, 225;
action of, on Halley’s comet, 363;
appearance of the sun to, 380, 381;
comets in his orbit, 381, 382.

Ursa Major, periodic time of a double star in, 398;
nebulous region of, 417.

Utah, deserts of, causing monsoons, 124.

Vacuum produced by shell-fish, 117;
existing in the air, 118.

Valz, M., telescopic planet discovered by, 21;
comet observed by, 358;
observations on a comet’s approach to the sun, 364;
cause assigned by, for contraction in diameter of comets, 377, 378.

Vapour, formation and dispersion of, 269, 270;
force developing, 277.

Variable stars, periodic fluctuation of lustre in, 390, 391;
new, appearing and vanishing, 392, 394;
missing, 395.

Variables, region of the, 122.

Vegetation, effect of, in lowering temperature, 243;
the two requisites for, 248;
strength and vitality of, 249;
chemical action of light influencing, _ib._;
laws of its distribution, 249-252;
distribution of marine, 252, 253;
theories of specific diversity of original distribution of, 253, 254.

Venus, zone of instability between the sun and, 21;
perturbation in the mean motion of the earth and, 26;
eclipsing Mercury, 42;
transits of, parallaxes calculated from, 52, 53;
astronomical tables of, 63;
climate, 226.

Vernal equinox, planetary motions estimated from, 9.

Vesta, astronomical tables of, 63;
no atmosphere surrounding, 226.

Vesuvius, revived volcanic action of, 234.

Vibrating plates used in experiments on musical sound, 144, 147.

Vibrations of the air producing sound, 129;
in music, 131;
number made by the human voice in a second, 132.

—— of the ether in natural and polarized light, 193;
in fluorescence of light, 196;
plane of, in polarized light, 223.

Vico, Padre de, comet discovered by, 370.

Vienna, observations on comets from, 370.

Vietch, James, comet with luminous rings discovered by, 374, 375.

Vincent, St., revival of an extinct volcano in, 234.

Virginia, daguerreotyped spectral image obtained in, 213.

Virgo, planetary conjunction between Libra and, 42;
variable star in, 392;
star vanished from, 395;
nebulous zone passing, 416, 417.

Viviers, transit of a comet across the sun observed from, 374.

Volcanic regions of the globe, 232;
annual number of eruptions, 233;
celebrated eruptions, _ib._;
earthquakes caused by, 234;
supposed causes of action, 235;
Sir John Herschel’s theory, 235-237.

Volta, Professor, electricity rendered manageable by, 297;
the world’s debt to, 328.

Voltaic electricity, first suggestions of, 297;
theory of the transmission of, 298;
construction of the battery, 298, 299;
theory of its production, 300;
characteristic properties, 300, 301;
action of, generating heat and light, 301-303;
arc, experiments, 303-305;
the, discharge oxidizing silver, 305, 306;
stratified light, 306, 307;
chemical decomposition effected by agency of, 307, 308;
crystallization, 308;
an agent in the fine arts, 309;
conductors of, _ib._;
relations of heat and, 310;
fish producing effects of, 310, 311;
science suggested by its influence on a magnetized needle, 312;
rotation effected by, 313, 314;
inducing magnetism, 314, 315;
distinction between static electricity and, 317;
unvarying dual force of, 334.

Voltaic pile, the, invention of, 297;
perfected, 298-300.

Vortices, molecular, theory of, 104.

Vosges mountains, temperature of mines in the, 228.

Vulpecula, nebula in, 409.

Wardhus, transit of Venus observed at, 53.

Watches, irregular action of, corrected by the laws of unequal
expansion, 272.

Water, constituent parts of, 111;
boiling point of, an estimate of mountain heights, 120;
as a medium for sound, 135;
light polarized circularly by, 194;
experiment deciding the velocity of light in, 202;
law of expansion of, 271;
process of congelation, 276;
boiling points of, 277;
decomposed by electric agency, 307;
as an electric conductor, 309;
rotating by electricity, 314.

Waterspouts, origin and cause of, 128.

Waterstone, Mr., magnetic property of the ethereal medium maintained
by, 357.

Waves neutralized by interference, 99.

——, atmospheric, over local districts, periods, dimensions of, 121,
122.

—— of sound, 131;
furnishing an illustration of reflections of sound and light, 137;
interference of, producing calm, 139.

Wedgwood, Dr., attempts of, to trace objects by means of light, 203,
204.

Week, the, of seven days, the most ancient and universal division of
time, 85.

Wells, increase of temperature in, 230, 231.

Welsh, Mr., observations made by, in a balloon ascent, 119.

West Indies, the, cause of hurricanes in, 126.

Wheels invented to test intensity of sound, 132, 133.

Wheat, range of its cultivation, 250.

Wheatstone, Professor, experiments in acoustics of, 132;
musical instruments invented by, 143;
paper on musical vibrations read by, 145;
experiments on sounding boards of, 150;
experiments on sound reinforced by resonance, 151;
instrument measuring velocities of electricity and light invented by,
202;
spectrum of an electric spark observed, 289;
speed of electricity measured, 289, 290;
experiments on the spectrum of Voltaic flame, 303.

Willis, Mr., articulating machine invented by, 151;
investigations of, into the mechanism of the larynx, 152.

Winds, trade, 122, 123;
monsoons, 124;
extra-tropical, in the North Atlantic, _ib._;
currents above the trade winds, 124, 125;
phenomena of rotatory motion, 125;
hurricanes, 125, 128;
agency of, influencing temperature, 244, 245.

Wines, range of cultivation of the best, 250.

Winter, atmospheric electricity in, 291.

——, mean temperature of, varying in the same latitude, 246, 247.

Wolf, Professor, periods of variation in solar heat computed by, 225.

Wollaston, Dr., experiments of, on sensitiveness to sound, quotation
from, 132;
experiment of, to show the effect of variable media on refraction,
156;
discovery of rayless lines in the solar spectrum, 162;
observations of, on the chemical properties of the solar spectrum,
203, 209;
magnetic rotation suggested by, 313;
light emitted by the heavenly bodies calculated, 404.

Xi Ursæ Majoris, periodic time of, 398;
velocity of the revolving star, 400.

Year, a, in Jupiter and Saturn, 66;
tropical change in its length, 80;
length of the sidereal, _ib._;
period of the mean, 83;
estimation of the Egyptian, 85;
first of our era, 86;
length of the, affected by a comet’s passage, 359.

Young, Dr., his calculation of the possible compression of solids, 78;
date of a horoscope determined by, 89;
density of a liquid column estimated by, 114;
exception adduced by, to a general law in acoustics, 137;
his theory of the pleasures of harmony, 142;
undulatory theory established by, 169;
data used by, to test his theory of light, 175;
illustration of, proving sound and heat kindred forces, 280, 281.

Zeta Cancri, a triple star, 395;
periodic time of, 398;
revolution, 400;
colours, 401.

Zeta Herculis, periodic time, eclipse of, 398;
light, 402.

Zinc, seleniate of, effect of temperature on its crystals, 107;
sulphate of, its crystals boiled in alcohol, 108.

——, electricity communicated to plates of, 220.

Zodiac, the, signs of, change in their positions, 80.

Zone of constant temperature in the atmosphere, 119;
laws of storms in the temperate and torrid, 127, 128;
of spots on the sun’s surface, its breadth, 224;
of constant temperature below the earth’s crust, 228;
comparative unequal distribution of land in temperate and torrid,
244;
of fixed stars, 385;
of stars nearest the sun, 390;
nebulous, 416;
of nebulous patches, 417;
of meteoric nebulæ, 423.

Zones of instability of planetary orbits, 21.

—— of temperature in the ocean, 101.

—— of vegetation on the Peak of Teneriffe, 250.

Zoophytes, specific distribution of, 254.

THE END.

LONDON: PRINTED BY W. CLOWES AND SONS, STAMFORD STREET,
AND CHARING CROSS.

These correspond to No. 1, 6, and 7 of Faraday’s plate in his 29th Series of Experimental Researches in Electricity.

Fig. 1.
Spiral nebulæ of 51 Messier, as seen by Lord Rosse.

Fig. 2.
Great nebula of Orion.
]

Footnotes

Footnote 1:

The mean distance of the earth from the sun is 95,000,000 miles, but
to avoid the inconvenience of large numbers, it is assumed to be the
unit of distance; hence the mean distance of Mars is 1·52369, or 1·5
nearly, that of the earth being = 1.

Footnote 2:

The obliquity given in the text is for the year 1858.

Footnote 3:

Sir John Herschel remarks that there are just as many thousands of
feet in a degree of the meridian in our latitude as there are days in
the year, viz. 365,000.

The Greenwich Observatory is in N. lat. 51° 28ʹ40ʺ.

Footnote 4:

Or more correctly 3422ʺ·325 and 238,793 miles, as deduced from Mr.
Adams’ more accurate calculations.

Footnote 5:

Neptune was discovered in the year 1846.

Footnote 6:

The satellites of the two great planets on the farthest verge of the
solar system form a singular exception to this law.

Footnote 7:

See the chapter on the Tides and Currents in the ‘Physical Geography,’
by the author, 4th edition.

Footnote 8:

Sir John Herschel on Meteorology.

Footnote 9:

Bakerian Lecture, by Michael Faraday, Esq. Phil. Trans. 1857.

Footnote 10:

See page 104.

Footnote 11:

M. Marbach of Breslau.

Footnote 12:

‘Meteorology,’ by Sir J. Herschel.

Footnote 13:

This theory of heat and motion originated with Mr. Joule, of
Manchester, who has maintained it with the greatest talent, both by
experiment and analysis; and it has had an able advocate in Professor
W. Thomson, of Glasgow.

Footnote 14:

To this remarkable man the world is indebted for the locomotive
railway system, which is rapidly advancing the civilization of
mankind. Britain may well be proud of its working classes, which can
produce such men; and Mr. George Stephenson is not the only one; there
are many others; but no man has ever had greater influence by his
labours and discoveries on human affairs.

Footnote 15:

‘Correlation of the Physical Forces, by W. R. Grove, Esq.,’ one of the
most remarkable and talented works that has appeared, to which the
author with pleasure acknowledges her obligations.

Footnote 16:

“Eripuit fulmen Cœlo, sceptrumque tyrannis,” is the inscription on a
medal struck in honour of Franklin.

Footnote 17:

Faraday.

Footnote 18:

Professor Matteucci still expresses doubts on this subject, but has
not yet finished his experiments.

Footnote 19:

Babbage.

Footnote 20:

Phil. Mag. for May 1858.

Transcriber's Notes

Some corrections were made to the original text. In particular, punctuation was corrected without further note. Inconsistent spelling and hyphenation was retained unless noted otherwise. There were two Notes 189 in the original; this was retained as printed. Spelling of Index entries was changed to reflect the body text where inconsistencies were found. Index page numbers were corrected where errors were found. Further corrections are noted below:

p. 50 0·005·1449 -> 0·0051449
p. 61 24,000 -> 240,000
p. 62 M. Leverrier -> M. Le Verrier
p. 84 in mean solar day -> in a mean solar day
p. 96 syzigies -> syzygies
p. 115 arrising -> arising
p. 120 Herchel -> Herschel
p. 123 generally know -> generally known
p. 159 Fraunhoffer’s -> Fraunhofer’s
p. 168 contaary -> contrary
p. 214 oxyde -> oxide
p. 216 aperature -> aperture
p. 296 M Niepce -> M. Niepcé
p. 306 torrecelian -> Torricellian
p. 307 potass -> potash
p. 350 de Roux -> le Roux
p. 423 Β -> β
p. 447 areal -> aërial
p. 456 perigree -> perigee
p. 471 108° -> 180°
p. 478 Meissier -> Messier