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F.

Fallacies in judging of the bulk of objects by their apparent
distance, 128, applied to the solution of the horizontal
Moon, 131.

First meridian, what, 152,

Fixed stars, why they appear of less magnitude when view-
ed through a telescope than by the bare eye, 378.
Their number, 379.

Their division into different classes and constellations, 380.

G.

General phenomena of a superior planet as seen from an in-
ferior, 106.

Georgium Sidus, its distance, diameter, magnitude, annual
revolution, 63, n.

Not readily distinguished from a fixed star, 63, n.
Inclination of its orbit, 63, n.

Place of its nodes, 63, n.

Its satellites, their distance, periods, and remarkable po-
sition of their orbits, 63, n.

Gravity, demonstrable, 74-75.

Keeps all bodies on the Earth to its surface, or brings
them back when thrown upward; and constitutes their
weight, 74, 86.

Retains all the planets in their orbits, 75.

Decreases as the square of the distance increases, 76.
Proves the Earth's annual motion, 77.

Demonstrated to be greater in the larger planets than in
the smaller; and stronger in the Sun than in all the
planets together, 112.

Hard to understand what it is, 113.

Acts every moment, 115.

Globe (Celestial), improved, 447.

H.

Harmony of the celestial motions, 78,
Harvest-Moon, 233–246.

None at the equator, 233.

Remarkable at the polar circles, 241.

In what years most and least advantageous, 245.

Heat, decreases as the square of the distance from the Sun
increases, 118.

Why not greatest when the Earth is nearest the Sun, 151.
Why greater about three o'clock in the afternoon than
when the Sun is on the meridian, 252.

Heavens, seem to turn round with different velocities as
seen from the different planets; and on different axes
as seen from most of them, 83.

Only one hemisphere of them seen at once from any one
planet's surface, 88.

Changes in them, 385.

Horizon, what, 88, n.

Horizontal Moon explained, 131.

Horizontal parallax, of the Moon, 132; of the Sun, 135;
best observed at the equator, 137.

Hour-circles, what, 153.

Hour of time equal to 15 degrees of motion, 153.

How divided by the Jews, Chaldeans, and Arabians, 395.
HUYGENIUS, his thoughts concerning the distance of some
stars, 32.

I.

Inclination of Venus's axis, 43.

Of the Earth's, 49.

Of the axis or orbit of a planet only relative, 145.

Inhabitants of the Earth (or any other planet) stand on op-
posite sides with their feet toward one another, yet each
thinks himself on the upper side, 86.

Julian period, 415.

J.

Jupiter, its distance, diameter, diurnal and annual revolu-
tions, 56, 57.

The phenomena of its belts, 57.

Has no difference of seasons, 58.

Has four Moons, 58, their grand period, 58, the angles
which their orbits subtend, as seen from the Earth, 59.
most of them are eclipsed in every revolution, 59.
The great difference between its equatorial and polar
diameters, 59.

The inclination of its orbit, and place of its ascending
node, 60.

The Sun's light 3000 times as strong on it as full Moon
light is on the Earth, 64.

Is probably inhabited, 65.

The amazing power required to put it in motion, 112.
The figures of the paths described by its satellites, 228.

L.

Light, the inconceivable smallness of its particles, 116; and
the great mischief they would do if they were larger;

117.

Its surprising velocity, 117, compared with the swiftness
of the Earth's annual motion, 139.

Decreases as the square of the distance from the lumi-
nous body increases, 118.

Is refracted in passing through different mediums, 119,

120.

Affords a proof of the Earth's annual motion, 139, 158.
In what time it comes from the Sun to the Earth, 156;
this explained by a figure, 157.

Limits of eclipses, 264.

Line, of the nodes, what, 265; has a retrograde motion, 267.
LONG (Rev. Dr.) his method of comparing the quantity of
the surface of dry land with that of the sea, 50.

LONG, his glass sphere, 90.

Longitude, how found, 152-155.
Lucid spots in the heavens, 384,
Lunar cycle deficient, 396.

Magellantic clouds, 385.

M.

Man, of a middle size, how much pressed by the weight of
the atmosphere, 123; why this pressure is not felt, 123.
Mars, its diameter, period, distance, and other phenomena,
55-56.

Matter, its properties, 74.

Mean anomaly, what, 176.

Mercury, its diameter, period, distance, &c. 40.

Appears in all the shapes of the Moon, 40.

When it will be seen on the Sun, 41.

The inclination of its orbit and place of its ascending notle,

41.

Its path delineated, 98.

Experiment to shew its phases, and apparent motion, 102.
Mercury (Quicksilver) in the barometer, why not affected
by the Moon's raising tides in the air, 260.

Meridian, first, 152.

Line, how to draw one, 166.
Milky way, what, 383.

Months, Jewish, Arabian, Egyptian, and Grecian, 391.
Moon, her diameter and period, 51.

Her phases, 51, 218.

Shines not by her own light, 52.
Has no difference of seasons, 52.
The Earth is a Moon to her, 52.

Has no atmosphere of any visible density, 52; nor seas,

53.

How her inhabitants may be supposed to measure their
year, 55.

Her light compared with day-light, 64.

The eccentricity of her orbit, 73.

Is nearer the earth now than she was formerly, 115.
Appears bigger on the horizon than at any considerable
height above it, and why, 131; yet is seen nearly under
the same angle in both cases; 131.

Her surface mountainous, 217: if smooth, she could give
us no light, 217.

Why no hills appear round her edge, 217.

Has no twilight, 218.

Appears not always quite round when full, 219.

Her phases agreeably represented by a globular stone
viewed in sunshine when she is above the horizon,
and the observer placed as if he saw her on the top of
the stone, 219.

Turns round her axis, 221.

The length of her solar and sidereal day, 221.

Her periodical and synodical revolution represented by
the motions of the hour and minute hands of a watch,

222.

Her path delineated, and shewn to be always concave to
the Sun, 223-227.

Her motion alternately retarded and accelerated, 226.
Her gravity toward the Sun greater than toward the

Earth at her conjunction, and why she does not then
abandon the Earth on that account, 227.

Rises nearer the time of sun-set when about the full in
harvest for a whole week than when she is about the
full at any other time of the year, and why, 233–240:
this rising goes through a course of increasing and de-
creasing benefit to the farmers every 19 years, 245.

Moon continues above the horizon of the poles for fourteen
Moon
of our natural days together, 246.

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Proved to be globular, 261; and to be less than the Earth,
262.

Her Nodes, 263; ascending and descending, 267; their
retrograde motion, 267.

Her acceleration proved from ancient eclipses, 278, n.
Her apogee and perigee, 305.

Not invisible when she is totally eclipsed, and why, 314.
How to calculate her conjunctions, oppositions, and eclip-

ses, 318.

How to find her age in any lunation by the Golden num-
ber, 452.

Morning and evening star, what, 104.

Motion, naturally rectilineal, 74.

Apparent, of the planets as seen by a spectator at rest

on the outside of all their orbits, 94; and of the hea-
vens as seen from any planet, 95.

Natural day, not completed in the time that the Earth turns
round its axis, 164.

New and full Moon, to calculate the times of, 318-328.
New stars, 396; cannot be comets, 385.

New style, its origin, 390.

Nodes of the planets' orbits, their places in the ecliptic, 38.
Of the Moon's orbit, 263; their retrograde motion, 267.
Nonagesimal degree, what, 220.

Number of Direction, 412.

0.

Objects, we often mistake their bulk by mistaking their dis-
tance, 128.

Appear bigger when seen through a fog than through
clear air, and why, 129; this applied to the solution of
the horizontal Moon, 131.

Oblique sphere, what, 93.

Olympiads, what, 279, n.

Orbits of the planets not solid, 39.

Orreries described, 430, 434, 437.

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