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]
Pingré, 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, [286] [287]
collective volume, [287]
atmospheres, [288]
Plantade, halo round Mercury, [244]
Pleiades, community of movement near,[ 41];
photographed spectra, [385]
measurements, [410]
photographs, [410] [411]
nebulæ, [410] [411]
Plücker, hydrogen in sun, [212]