ter Posidonius, 87

Schwabe, and Sun-spots, 40

Seas in the Moon, 82

Secchi, and stellar spectra, 479

Shoal of shooting stars, 377;
dimensions, 377

Shooting stars (_see_ Stars, shooting)

Sickle, the, 421

Sidereal aggregation theory of Sir W. Herschel, 529

Siderite, Rowton, 395

Sinus Iridum, 83

Sirius, change in position of, 425;
companion of, 427, 428;
exceptional lustre of, 110;
irregularities of movement of, 426;
larger than the Sun, 110;
most brilliant star, 419;
periodical appearances of, 157;
proper motion of, 425;
spectrum of, 479;
velocity of, 426;
weight of, 427

Smyth, Professor C.P., 493

Sodium, colour of flame from, 49;
in the Sun, 50

Solar corona, prominences etc. (_see under_ Sun)

Solar system, 107-121;
Copernican exposition of the, 7;
influence of gravitation on, 149;
information respecting, obtained by observing the transit of Venus, 174;
island in the universe, 121;
minor planets, 229-244;
moment of momentum, 554;
movement of, towards Lyra, 457;
origin of, as suggested by the nebular theory, 526;
position of Saturn and Uranus in, 297, 305

South, Sir James, 12

Spectra of stars, 479

Spectro-heliograph, 58

Spectroscope, 43-56;
detection of iron in the Sun by the, 50

Spectroscopic binaries, 487

Spectrum analysis, 47;
dark lines, 49, 50;
gaseous nebulae, 474;
line D, 48, 49

Speculum, the Rosse, 20

Spica, 423, 487

Spider-threads for adjusting the micrometer, 86;
for sighting telescopes, 22

Spots on the Sun, 36-43;
connection with magnetism, 42;
cycles, 41;
duration, 41;
epochs of maximum, 42;
motion, 36;
period of revolution, 40;
Scheiner's observations, 36;
zones in which they occur, 39

Star clusters, 461-464;
in Hercules, 462;
in Perseus, 462

Stars, apparent movements due to precession, nutation, and aberration, 504;
approximate number of, 28;
attraction inappreciable, 316;
catalogues of, 310, 311, 409, 431;
charts of, 325, 328;
circular movement of, 505-507

Stars, distances of, 441;
Bessel's labours, 442-449;
Henderson's labours, 442;
method of measuring, 443-445;
Struve's work, 442, 448, 449;
parallactic ellipse, 444-449

Stars, double, 434;
Bode's list, 435;
Burnham's additions, 439;
Cassini, 434;
Herschel, 435, 436;
measurement, 435, 436;
revolution, 436;
Savary, 436;
shape of orbit, 436;
variation i