Line, meridian, method of drawing, 40
Logarithms invented by Baron Napier, improved by Urfinus and Briggs, 28
Longitude of the heavenly bodies, 251 of places on the earth, method of finding, 274
Long, Dr., his account of the solar spots, 66
Lovelie's observations on the moon's ring, 126
Lowe's, Mr., method of finding the longitude, 274
Lunation, or month, 61
Mackay, Mr., method of finding the longitude, 274
Mars, spots first seen, 155 bright about the poles, 156 Dr Herschel's account of, 157 appear and disappear, 158 white about the poles, 162 position of the poles, 159 seasons, 160 resembles the earth, 161
Mars, his form spheroidal, No 163 difference of diameters, 164 atmosphere, 165
Maskelyne, Dr., improves the lunar method of finding the longitude, 36
Mercury's apparent motions, 135 diameter, 136 nature, 137
Meridian explained, 37 line, method of drawing, 40
Milky-way, 211
Moon's motion in her orbit, 79 orbit elliptical, 80 eccentricity, 81 eviction, 83 variation, 84 annual equation, 85 revolution of her nodes, 86 parallax, method of determining, 87 distance, 89 phases, 90 is opaque, 91 mode of measuring the year, 93 the earth appears a moon to it, 92 longitude found, 94 nonagesimal degree, 98 eclipses, 99 period, 100 why visible when eclipsed, 101 eclipses observed with difficulty, 102 number in a year, total and annular, 104 extent of shadow and penumbra, 107 size, 111 light, 112 spots, 113 names of, ib. inequalities of surface, 114 method of measuring mountains, 115 mountains, height of, overrated, 116 volcanoes, 119 substance, conjectures of, atmosphere, existence of, disputed, 121 ring observed in eclipses, 123 lightning, 127 height of atmosphere accounted for, 128 has no sensible atmosphere, 131 libration, 133 theory, 134 tendency the same as gravitation, 350 motion explained, 351 inequalities, 377 nearest the earth when least attracted, 379 orbit, cause of dilatation, 380
A a z Moon's Moon's orbit changed by the action of the sun, 381 nodes, 382 motion explained, 384 inclination, 383 motion, irregularities from being elliptical, 385 orbit, inequality in the eccentricity, 391 inequalities computed, 392 mean distance, secular equation, 393 has no atmosphere, why, 399
Motion, definition of, 331 Motions, of the, 51
N Nadir, 37 Napier, Baron, invents logarithms, 26 Nebula, our sidereal system, one, 236 extent, 239 how to be delineated, 241 Nebulae in the milky-way, 219 arranged in strata, 220 assume various shapes, 221 how formed, 231 vacancies, how occasioned, 232 decay and recomposition, 242 universe composed of, 243 size and distance, 244 time of forming, 245 planetary, 247 Newton, Sir Isaac, his discoveries, 31 determines the motions of the comets, 324 his opinion of comets defended, 316 observations on the precession of equinoxes, 407 sketch of his investigation, 408 determination of the form and dimensions of the earth, 409 examination of phenomena of precession on mechanical principles, 410 Node, ascending, 86 Nodules on the luminous clouds of the sun, 75 Number, golden, 61 Nutation, lunar, 421 compared with precession, 423
O Observatory, portable, 364 Openings formed by the sun's luminous clouds being removed, 72 Oscillation of the planetary system, 369
P Pallas, planet, elements not precisely known, 183 Perigee of the moon's orbit, 81 of the planets, 293 Phanicians taught astronomy by the Egyptians, 7 apply it to navigation, 7 Philostratus asserts the annual motion of the earth round the sun, 11
Planets, apogee and perigee, difference of apparent diameters, 293 appearances of superior, explained, 294 orbits and laws of their motions, 295 heliocentric circles, 296 nodes, 297 tables of elements, 298 revolve round the sun, 343 in consequence of a force in the sun, 344 the same tendency in all, 346 and same in their satellites, 347 react on the sun, 354 densities calculated, 356 masses, table of, 357 gravity at their surfaces, 359 secular and periodical inequalities, 360 motion of the aphelion motions, method of correcting, 361 Jupiter and Saturn influence each other's motions, 362 deflection of, towards each other, 363 Pendulum regulated by gravitation, 337 Precession of equinoxes, 257—259 observation by Newton and others, 407 Newton's investigation, 408 lunar, greatest equation, 420 425 Ptolemy, his system erroneous, 16 Ptolemy Philadelphus encourages the sciences in Egypt, 12 Pythagoras improves astronomy, 11 correct notions of the solar system, ib. of the moon's light, ib. of the milky-way, ib.
Q Quadrants, 361 Quadratures of the moon, 90
R Revolution of a body round a centre explained, 339 Regiomontanus constructs astronomical apparatus, calculates lunations and eclipses, 20 writes a theory of planets and comets, ib. Ridges of the sun's luminous clouds, 74 Reimer discovers the progressive motion of light, 33 Rothman, an astronomer, 23 Ring of Saturn, discovery concerning, by Dr Herschel, 395
S Satellites, tend to the sun, 347 to their primaries, 349 irregularities in Jupiter's, 394 Saturn, telescopic appearance of, 178 ring discovered by Huygens, 179 supposed to revolve round its axis, 180 diameter, ib. satellites, two discovered by Herschel, 183 number, 329 Seasons explained, 44 changes illustrated, 290 different, explained, 291 Sector, equatorial, 362 Selenographia compiled by Hevelius, 30 Shadows of the sun's luminous clouds, 93 Shepherd, Asiatic, observe the heavens, 255 Signs of the zodiac, 52 Society, Royal, founded in London, 80 Stars, fixed, occultations by the moon, 130 Style, old, 64 new, ib. Sun, annual motion, 39 altitude, 41 motion, method of ascertaining, 42 not uniform, 45 diameter varies, 46 distance varies, 47 motion varies, 48 orbit, elliptical, 50 varies, 53 distance determined, 54 spots, first discovered, 65 Long, Dr, his account of them, 66 move from west to east, 67 observed by different astronomers, 68 Dunn, Mr, his account of them, 69 appearances of the luminous clouds, 72—76 two regions of clouds, 77 theory of phenomena, 78 eclipses, 103 beginning and ending, 108 account of one by Dr Halley, 124 his place in the universe, 224 centre attracts all bodies, 348 moves round the common centre of gravity, 364 Synodic of the moon, 90 Stars, fixed, number increased by telescopes, 192 difference in magnitude, 193 telescopic, 194 uniformed, 195 division in constellations, and uses, 196 ASTROPE WELLS, near Banbury in Oxfordshire, are recommended as excellent in many disorders. The water is a brisk, nutritious, pleasant-tasted chalybeate, and is also gently purgative. It should be drank from three to five quarts in the forenoon.