ossibility of ejecting meteorites, 402;
possibly fractured off from the earth, 543;
prehistoric tides on, 548, 549;
produces precession, 497-499;
proximity to the Earth of, 73, 75;
receding from the Earth, 545;
relative position of with regard to the Earth and the Sun, 76, 77;
revolution of, round the Earth, 75, 76, 558;
"seas" on, 82, 83;
shadows of, 85;
size of, compared with that of the Earth, 74;
test for chronometers, a, 80;
thraldom of terrestrial tides, 549;
waterless, 100;
weather not a affected by the phases of, 82;
weight of, 74

Motion, laws of planetary, 138, 141, 142, 147, 148

Mountains of the Moon, 83, 85, 93

N

Nasmyth, Mr., and the formation of lunar craters, 95

Natural History Museum, meteorites, 394

_Nautical Almanack_, 189

Neap Tides, 538

Nebula, in Andromeda, 469;
annular, in Lyra, 469;
in Orion, 269, 461, 466-469;
colour of, 468;
magnitude of, 468;
nature of, 467;
planetary, in Draco, 470;
simplest type of a, 528;
various grades of, 528

Nebulae, 464-472;
condensation, 528;
distances of, 464;
double, 470;
Herschel's labours respecting, 464-465, 528, 529;
number of, 466;
planetary, 470;
self-luminous, 464;
smallest greater than the Sun, 464;
spiral, 470

Nebular theory, the, 526

Neptune, 112;
Adams's researches, 324-326, 332;
Challis's observations of, 326-328;
density of, 558;
diameter of, 333, 558;
disc of, 332;
discovery (1846) of, 315;
distance from the Sun of, 334, 558;
Lalande's observations of, 332, 333;
Le Verrier's calculations, 324-332;
moment of momentum of, 554;
orbit of, 117;
periodic time of, 558;
revolution of, 334;
rotation of uncertain, 333;
satellite of, discovered by Mr. Lassell, 559;
size of, compared with other planets, 119;
vaporous atmosphere of, 333;
weight of, 333

Newall, Mr. H.F., and Capella, 487;
and the values of velocity of stars, 483

Newcomb, Professor, 9, 264, 267, 522

Newton, Professor, and meteoric showers, 377, 384

Newton, Sir Isaac, discovery of gravitation verified Kepler's laws, 144;
dynamical theory, 214;
illustrations of his teaching, 144-147;
law of gravitation and, 125, 126, 537;
parabolic path of comets and, 338-340;
reflecting telescope, 19;
weight of the Earth and, 203

Nickel in the Sun, 50

Nineveh, astronomers of, 156

Nordenskjoeld, and the Ovifak meteorite, 407

Nova Cy