rominences, 167, 197, 198;
of coronal spectrum, 171, 188, 190;
of prominence-spectrum, 195, 198;
of arc-spectrum, 206, 211;
of solar spectrum, 210, 211, 215, 439, 440;
of Uranian spectrum, 305;
of cometary spectra, 354, 357;
of stellar and nebular spectra, 382-384, 396, 398, 400, 407;
lunar, 152, 153, 268;
detection of comets by, 178, 338, 369;
of asteroids, 284;
of new stars, 399;
use of, in transits of Venus, 234, 236, 240;
Mars depicted by, 277, 281;
Jupiter, 297, 408;
comets, 353, 354, 368, 412;
nebulae, 395, 401, 407-409, 411, 425;
Milky Way, 424, 425;
star-charting by, 413, 414;
star-parallaxes by, 417;
rapid improvement, 438

Photometry, stellar, 49, 420, 421;
of planetary phases, 245, 288;
of Saturn's rings, 299;
photographic, 421

Photosphere, named by Schroeter, 55;
structure, 151, 152, 164, 165

Piazzi, star catalogues, 31;
parallaxes, 33;
motion of 61 Cygni, 35;
birth and training, 72;
5-foot circle, 72, 121;
discovery of Ceres, 73, 74

Picard, Saturn's dark ring, 86;
sun's distance, 228

Pickering, E. C., photometric measures of Martian satellites, 282;
of minor planets, 287;
variability of Japetus, 302;
of Neptune, 305;
meteoric photography, 339;
gaseous stars, 379;
hydrogen spectrum in stars 383;
spectrographic results, 385;
eclipses of Algol, 390;
photographic celestial surveys, 399;
star density in Pleiades, 411;
photometric catalogues, 420, 421;
photographic photometry, 421;
white stars in Milky Way, 425;
climate of Arequipa, 435;
horizontal telescope, 437

Pickering, W. H., corona of 1886, 185;
coronal photographs, January 1, 1889, 186;
lunar twilight, 264;
lunar volcanic action, 267;
melting of snow on Mars, 277;
Martian snowfall, 281;
Jupiter's satellites, 292;
photographs of comets, 368;
of Orion nebula, 408;
observatory at Arequipa, 435

Pingre, phenomena of comets, 92, 96

Planets, influence on sun-spots, 163;
periods and distances, 228;
intra-Mercurian, 248-250;
inferior and superior, 288;
trans-Neptunian, 306, 307;
origin, 309, 313;
relative ages, 314, 315

Planets, minor, existence inferred, 71, 72;
discoveries, 73-75, 77, 283, 284;
solar parallax from, 237-239;
distribution of orbits,