Olmsted, radiant of Leonids,328;orbit,329
Oppenheim, calculation of Schmidt's comet,363
Oppolzer, E. von, theory of sun-spots,159;variability of Eros,285
Oppolzer, Th. von, Winnecke's comet,94;comet of 1843350
Oxygen in sun,213-215;telluric absorption,214in stars,384
Packer, variable stars in cluster,436
Palisa, search for Vulcan,181250;discoveries of minor planets,283
Pallas, discovery,74;inclination of orbit,75,286diameter,75,287288
Pape, Donati's comet,345
Parallax, annual, of stars,10,16,33,36,416-418;horizontal, of sun,227Encke's result,230232[Pg 483]improved values from oppositions of Mars,231237from light velocity,231232241from recent transits,236240from observations of minor planets,238239general result,242
Paris Catalogue of Stars,415
Paschen, oxygen in sun,215;solar temperature,220
Pastorff, drawings of the sun,101
Peirce, structure of Saturn's rings,298
Perrine, eclipse photographs,190;nature of corona,191observationof Holmes's comet,369nebula round Nova Persei,401
Perrotin, rotation of Venus,252;markings on,255canals of Mars,279clouds on Mars,281striation of Saturn's rings,299rotation and compression of Uranus,303304changes of Pons's comet,366Maia nebula,410measures of double stars,419
Perry, eclipse of December, 1889187
Personal equation,123235
Peter, star-parallaxes,417
Peters, C. A. F.,parallax of 61 Cygni,36disturbed motion of Sirius,42
Peters, C. F. W., orbit of Leonid meteors and comet,332
Peters, C. H. F., sun-spot observations,147148;discoveries of minor planets,283star maps,284415
Peytal, description of chromosphere,69
Phobos, rapid revolution,282283314;tidal relations,320321
Photography, solar,145153154165;of corona,166173175178181185-190without an eclipse,178-180of prominences,167197198of coronal spectrum,171188190of prominence-spectrum,195198of arc-spectrum,206211of solar spectrum,210211215439440of Uranian spectrum,305of cometary spectra,354357of stellar and nebular spectra,382-384396398400407lunar,152153268detection of comets by,178338369of asteroids,284of new stars,399use of, in transits of Venus,234236240Mars depicted by,277281Jupiter,297408comets,353354368412nebulæ,395401407-409411425Milky Way,424425star-charting by,413414star-parallaxes by,417rapid improvement,438
Photometry, stellar,49,420421;of planetary phases,245288of Saturn's rings,299photographic,421
Photosphere, named by Schröter,55;structure,151152164165
Piazzi, star catalogues,31;parallaxes,33motion of 61 Cygni,35birth and training,725-foot circle,72,121discovery 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,287variability of Japetus,302of Neptune,305meteoric photography,339gaseous stars,379hydrogen spectrum in stars383spectrographic results,385eclipses of Algol,390photographic celestial surveys,399star density in Pleiades,411photometric catalogues,420421photographic photometry,421white stars in Milky Way,425climate of Arequipa,435horizontal telescope,437
Pickering, W. H., corona of 1886185;coronal photographs, January 1, 1889186lunar twilight,264lunar volcanic action,267melting of snow on Mars,277Martian snowfall,281Jupiter's satellites,292photographs of comets,368of Orion nebula,408observatory at Arequipa,435
Pingré, phenomena of comets,92,96
Planets, influence on sun-spots,163;periods and distances,228intra-Mercurian,248-250inferior and superior,288trans-Neptunian,306307origin,309313relative ages,314315
Planets, minor, existence inferred,71,72;discoveries,73-75,77,283284solar parallax from,237-239distribution of orbits,286287collective volume,287atmospheres,288
Plantade, halo round Mercury,244
Pleiades, community of movement near,41;photographed spectra,385measurements,410photographs,410411nebulæ,410411
Plücker, hydrogen in sun,212
Plummer, solar translation,39;Encke's comet,99
Plutarch, solar corona,65
Pogson, prominence spectrum,168;reversing layer,172discovery of a comet,335339new star in cluster,395[Pg 484]new star in cluster,395
Pond, errors of Greenwich quadrant,28;controversy with Brinkley,33
Pons, discoveries of comets,90,94,365
Pontécoulant, return of Halley's comet,101
Poor, C. Lane, calculation of Lexell's comet,367
Porter, solar translation,40
Pouillet, solar constant,216225;temperature of the sun,217of space,270
Poynting, mean density of the earth,261
Prince, glow round Venus,253
Pritchard, parallax of β Aurigæ,388;photographic determinations of stellar parallax,417photometric catalogue,420
Pritchett, corona of January, 1889186;red spot on Jupiter,294
Proctor, glare theory of corona,182;speed of ejections from sun,205transit of Venus,233distance of sun,236atmosphere of Venus,254rotation of Mars,275map and canals of Mars,278279condition of great planets,289Nova Andromedæ,403status of nebulæ,422423structure of Milky Way,424star drift,426
Procyon, satellite,42; parallax,417
Prominences, observed in 184263,64,68;described by Vassenius,68observed in 185170photographed during eclipse,167188190without eclipse,197198spectrum,168178194195198199spectroscopic method of observing,168-170194-196white,183184chemistry,195199classification,196distribution,199movements in,204-206heat of development,220
Quetelet, periodicity of August meteors,329
Ranyard, drawing of sun-spot,101;coronal types,175185lunar atmosphere,265Jupiter's markings,297meteors from fixed radiants,341cometary trains,348tenuity of nebulæ,409
Rayet, spectrum of prominences,168170
Red spot on Jupiter,293296
Reduction of observations,31;Bessel's improvements,32,122Baily's,60
Refraction, atmospheric,31;effects looked for in comets,106353Cytherean,235253254lunar263264
Reichenbach, foundation of Optical Institute,28,34,122
Repsold, astronomical circles,41,122;Cape heliometer,416
Resisting medium,93,94,360
Respighi, slitless spectroscope,173;prominences and chromosphere,194196199solar uprushes,205spectrum of γ Argûs,380
Reversing layer, detected,171172;photographed,172189depth,173
Riccioli, secondary light of Venus,255
Riccò, trials with coronagraph,180;distribution of prominences,199spectrum of Venus,254spot on Jupiter,294spectrum of great comet,364
Richer, distance of the sun,228
Ristenpart, solar translation,40
Ritchey, nebula round Nova Persei,401;photographs of nebulæ,432
Ritter, development of stars,375
Roberts, A. W., southern variables,392
Roberts, Isaac, search for ultra-Neptunian planet,306;photographs of Orion nebula,408of Andromeda nebula,409of the Pleiades,411
Roberval, structure of Saturn's rings,299
Robinson, reflectors and refractors,431
Roche, inner limit of satellite-formation,301;modification of nebular hypothesis,321
Römer, star places,10;invention of equatoreal and transit instrument,120of altazimuth,121velocity of light,231satellite transit on Jupiter,291
Rosenberger, return of Halley's comet,101
Rosetti, temperature of the sun,219
Rosse, third Earl of, biographical sketch,114;great specula,115-117discovery of spiral nebulæ,118resolution of nebulæ,119climate and telescopes,434
Rosse, fourth Earl of, experiments on lunar heat,269
Rost, nature of sun-spots,54
Roszel, mass of asteroids,287
Rowland, photographic maps of solar spectrum,210440;elements in run,213concave gratings,439440
Rümker, observation of Encke's comet,90
Russell, H. C., red spot on Jupiter,295;change in Argo nebula,404photographs of Nubeculæ,425[Pg 485]photographs of Nubeculæ,425
Russell, H. N., atmosphere of Venus,254
Rutherfurd, lunar photography,268;star spectra,372photographs of the Pleiades,410diffraction gratings,439
Sabine, magnetic and sun-spot periods,127128130
Safarik, secondary light of Venus,256;compression of Uranus,304
Satellites, discoveries,110282293;transits,291292variability,292302origin,309318
Saturn, low specific gravity,298;rotation,302spectrum,303
Saturn's rings, first disclosure,85;dusky ring,86stability,298300meteoric constitution,300eventual dispersal,301
Savary, orbits of double stars,46
Savélieff, solar radiation,164225
Sawerthal, discovery of a comet,366
Schaeberle, discovery of Procyon's satellite,42;coronal photographs,187188theory of corona,191meteoric photography,339discovery of a comet,355
Schaeberle and Campbell, observations of Jupiter's satellites,292
Scheiner, Father, nature of sun-spots,52,54;equatoreal instrument, 120notesolar rotation,146darkening of sun's limb,221
Schiener, Dr. J., photospheric structure,165;spectrographic researches,384405spectrum of Andromeda nebula,403stars and nebulæ in Orion,407
Schiaparelli, rotation of Mercury,247;of Venus,251252spots on Mars,275snow-cap,277canals,278-280compression of Uranus,304comets and meteors,327331332338anomalous tail of great comet,364Pons's comet,365origin of comets,370measures of double stars,419
Schmidt, A., circular refraction in sun,159
Schmidt, J., sun-spot period,126;lunar rills,263lunar maps,265disappearance of Linné,267cometary appendages,363new stars,393
Schönfeld, extension of Bonn Durchmusterung,412414
Schrader, construction of reflectors,243
Schröter, a follower of Herschel,5;motions of sun-spots,146biographical sketch,243244observations on Mercury,244246247on Venus,250-253255on the moon,263a lunar city,265Linné,267spots on Mars,275Jovian markings,290
Schülen, perspective effects in sun-spots,54
Schuster, photographs of corona,178185;spectra of oxygen,214
Schwabe, sun-spot periodicity,125126
Secchi, chromosphere,70;Biela's comet,97cyclonic movements in sun-spots,144distribution,148profundity,154nature,156158constitution of photosphere,151eclipse observations,166167reversing layer,171observations of prominences,194196199absence of helium absorption,213temperature of the sun,218solar atmospheric absorption,221Martian canals,279spectrum of Uranus,304of Coggia's comet,343stellar spectral researches,372373carbon stars,372381gaseous stars,377
See, stellar orbits,42,46;measures of Neptune,84measures of Uranus,304belts of Neptune,306colour of Sirius, 375notesouthern double stars,419evolution of stellar systems,420
Seeliger, photometry of Saturn's rings,299;rationale of new stars,396
Seidel, stellar photometry,420
Sherman, spectrum of Nova Andromedæ,395
Short, reflectors,4,109115121;chromosphere,68satellite of Venus,256striation of Saturn's rings,299
Sidereal science, foundation,9,442;condition in 178510progress,50
Sidgreaves, spots and faculæ,159
Siemens, regenerative theory of the sun,312
Simony, photographs of ultra-violet spectrum,215
Sirius, a binary star,41;mass,42parallax,42,416spectrum,133373383former redness, 375noteradial movement,386387
Smyth, Admiral, Donati's comet,324
Smyth, Piazzi, oxygen spectrum,215;lunar radiations,269expedition to Teneriffe,434
Solar constant,216225
Solar spectrum, fixed lines in,133-135;maps,133136206210211224440distribution of energy,222223
[Pg 486]Solar system,translation through space,15,39,40,406development,308309313-316322complexity,441