Chapter LXI: Appendix: Table I (2)

Oxygen, telluric absorption by, 22, 23;
presence in the sun, 26, 27, 29;
dark lines of in stellar spectra, 175, 181, 191, 195, 232, 239, 241,
338, 465

Packer, variable stars in cluster, 433

Palmer, distribution of stars in Hercules cluster, 432

Parkhurst, phases of Y Boötis, 313, 314;
irregularity of U Geminorum, 366;
light-curve of S^2 Cygni, 367

Paschen, temperature and energy spectrum, 66

Peek, Sir Cuthbert, work at observatory, 254;
light-curve of S Ursæ Majoris, 353;
light-change of R Lyncis, 356

Pereira, description of a sun-spot, 75;
drawing of a sun-spot, 78

Perrine, expansion of nebulosity about Nova Persei, 394

Perrotin, colours of double stars, 259, 261

Perry, Father, dark helium-line in sun-spot spectra, 94

Perry, Professor, masses and temperatures of stars, 274

Peter, measurements of clusters, 189, 426

Photography, advantages, 3, 5;
lunar, 7;
double slit, 9, 18, 50;
solar, 17, 25, 49;
chromospheric, 18, 99, 100, 114;
of reversing layer, 45, 46;
of corona, 132–135;
of temporary stars, 175, 376, 382, 387, 388, 392;
of nebulous stars, 190, 462, 464, 465, 466;
of irregular nebulæ, 205, 507, 508, 509, 511, 513–515;
of Nova Persei nebula, 394, 395;
of Pleiades nebulosities, 416–420;
of white nebulæ, 442–444, 448, 449, 455, 458;
of planetary and annular nebulæ, 472, 484, 487, 490, 493;
of Orion nebula, 495–497;
of variable nebulæ, 525, 529;
of Milky Way, 539–541;
with portrait-lenses, 423, 513

Photometry, its dual aspect, 8;
of the Pleiades, 421

Photosphere, a limiting surface, 15, 16;
temperature, 49, 64–66, 69;
constitution, 62, 63, 69, 70;
problem of formation, 402

Piazzi, nebulosity of 55 Andromedæ, 466, 467

Pickering, E. C., discovery of a second hydrogen series, 54, 237;
general absorption in solar atmosphere, 70;
spectral character of galactic stars, 173, 196;
fifth stellar type, 188;
spectrum of Procyon, 203;
of 11 Monocerotis, 233;
of Wolf-Rayet stars, 239, 240;
composite stellar spectra, 265;
rotation of Altair, 281;
eclipses of Algol, 302, 303;
light-curves of eclipsing stars, 309;
phases of U Cephei, 310;
of W Delphini, 315;
of S Antliæ, 331;
binary character of V Puppis, 334;
of β Lyræ, 338;
light-curve of T Andromedæ, 357;
spectrum of U Geminorum, 366;
of Nova Persei, 392;
photograph of Nova Persei, 388;
spectra of stars in Præsepe, 413;
counts of Pleiades, 416;
surmised cause of cluster-variability, 436;
catalogue of stars in M 5, 438;
detection of stellar nebulæ, 481, 482;
spectrum of Looped nebula, 512

Pickering, W. H., spectrum of white prominences, 110;
photographs of nebulæ, 190;
of Orion trapezium;
of colossal involving nebulosity, 496;
movements of the entangled stars, 497;
estimated distance, 498;
spectrum of Orion nebula, 503

Pigott, discovery of R Scuti, 363;
of R Coronæ, 371

Planetary nebulæ, affinities, 188;
criteria of distinction from nebulous stars, 461, 469;
spheroidal in shape, 469;
radial velocities, 470, 475, 483;
complex structure, 471;
nuclear stars, 473, 474, 532;
spectra, 475–479;
bi-nuclear, 480;
distribution, 544

Plassmann, light-change of λ Tauri, 307

Pleiades, helium spectra, 181, 194, 413, 420;
nebulously involved, 189, 230, 416–420;
general stability in light, 406, 421;
drifting movement, 409, 415;
a typical nebulous cluster, 415;
fewness of real components, 416;
recession from the sun, 420;
centrifugal tendency, 497

Pluvinel, Fraunhofer-lines in coronal spectrum, 132

Pogson, variability of S Ursæ Majoris, 353;
of R Cephei, 369

Polaris, spectrum, 205;
triple system, 298;
constant brightness, 327

Pollux, estimate of mass, 206

Porro, light-curve of U Orionis, 350

Præsepe, measures of components, 412;
their spectra, 413

Pritchard, parallax of β Aurigæ, 291

Proctor, refraction in sun-spots, 80

Procyon, spectral relationships, 182, 203;
mass, 204;
semi-obscure companion, 400

Prominences, chromospheric outgrowths, 16, 19, 101;
photography, 18, 99, 109;
varieties, 102, 103;
movements in, 103, 106–109;
structure, 103, 105, 109;
diametrical situations, 106;
white and black, 110, 120;
spectrum, 115–121;
relations with coronal jets, 129, 130;
ejective character, 137;
movements in latitude, 153

Pupin, coronoidal discharges, 140

Pye, observation of reversing layer, 44

Rambaut, orbit of β Aurigæ, 291

Ramsay, discovery of helium, 29, 56;
its electric conductivity, 59

Ranyard, photograph of a sun-spot, 76;
coronal structures, 126;
coronal types, 128;
central star in Lyra nebula, 487;
conformation of Orion nebula, 496;
allineation of stars in Key-hole nebula, 507;
dimness of nebulæ, 532;
their small mean density, 533, 534

Red stars, Antarian, 179, 183, 209;
carbon type, 179, 184, 215;
variable in tint, 254–258;
in light, 352, 370, 374;
relation of colour-intensity to length of period, 358

Reed, halts in stellar light-change, 359

Refraction, effects of in sun, 165–167

Regulus, a helium star, 184

Reversing layer, disclosure during eclipses, 9, 44;
position in the sun, 16, 46, 161;
photographed, 45, 46;
analysis, 47, 48, 162;
temperature, 49;
tranquillity, 50;
slight pressure in, 51;
optical rationale, 166, 167

Riccò, level of sun-spots, 80

Rigel, absorption in by helium, 174, 181, 191;
by silicon, 193;
luminosity, 192

Ritchey, expanding nebula round Nova Persei, 394

Ritter, star-masses and temperatures, 274, 276

Roberts, A. W., system of RS Sagittarii, 308;
detection and investigation of eclipsing stars, 313, 314, 316;
phases of δ Cephei, 320;
of R Trianguli, 324;
of R^2 Centauri, 331;
of V Puppis, 334;
of S Aræ, 336;
magnitude of η Carinæ, 371

Roberts, Isaac, photographs of a circular nebula, 190, 514;
of clusters, 410, 433, 436;
of the Andromeda nebula, 440;
of other spirals, 441, 442;
of rifted nebulæ, 447, 448;
of a nebulous star, 465;
of Owl nebula, 472, 473;
of annular nebulæ, 489, 490;
of Trifid, 509;
of Omega nebula, 511;
of nondescript nebulæ, 517, 518, 519, 520;
photographic search for a vanished nebula, 525

Robinson, observation of the Owl nebula, 472

Rosetti, solar temperature, 65

Rosse, Lord, arrangement of stars in M 37, 410;
nebulosity of 15 Monocerotis, 426;
perforated cluster, 435;
ray nebula, 442;
spiral nebulæ, 443, 444, 445;
cometary nebula, 446;
observation of 55 Andromedæ, 466;
Owl nebula, 472, 473;
central stars in annular nebulæ, 486, 489, 493;
Crab nebula, 518;
contours of gaseous nebulæ, 534

Rotation, solar, spectroscopically determined, 7, 19, 144, 145;
from spot-movements, 83, 142, 143;
from faculæ, 145, 146;
attempted explanation of anomalies, 147–149;
theoretical effects in stellar spectra, 280, 281;
unapparent to observation, 282–284;
of planetary nebulæ, 469, 470

Rowland, invention of concave gratings, 18;
map of solar spectrum, 25;
solar chemistry, 25, 26, 30, 31, 32;
photographs of metallic spectra, 26, 91;
variable Fraunhofer-line, 37

Rubens, temperature and spectral energy-curve, 66

Runge, duplicity of clevite-ray, 57;
hydrogen-envelope of a star, 241;
spectrum of Orion nebula, 501

Runge and Paschen, oxygen triplet in solar spectrum, 29;
spectral series, 53, 54;
spectrum of helium, 57, 58

Russell, H. C., movements of stars in Jewel cluster, 414;
photographic and visual observations of Key-hole nebula, 507, 508;
photographs of Coalsack region, 540;
of nebulæ, 544

Russell, H. N., density of eclipsing stars, 307, 308, 310

Rydberg, spectral series, 53;
third hydrogen series, 187, 190, 232, 237, 238, 240

Sabine, sun-spot and magnetic periods, 3, 13

Safarik, periodicity of S Persei, 370

Sampson, origin of the solar rotation, 148

Savélieff, solar radiation, 68, _note_

Sawyer, variability of U Ophiuchi, 311;
of R Canis Majoris, 313;
of RX Herculis, 315;
of T Vulpeculæ, 325;
luminous outbursts of R Lyræ, 368;
minimum of R Coronæ, 372

Schaeberle, perspective effects in corona, 124;
coronal photographs, 126, 129;
ejective theory of corona, 137, 165;
conformation of nebulæ, 474, 492;
photograph of a nebula, 515

Scheiner, heat-relations of magnesium-lines, 49, 181, 187, 200, 201;
locus of general absorption in sun, 71;
temperature of the corona, 138;
search for electrical vibrations in sunlight, 159;
carbon bands in stars, 184;
constitution of solar stars, 207;
temperature of electric spark, 273;
incipient brightening of stellar hydrogen bands, 284;
photographic catalogue of stars in M 13, 433;
spectrograph of Andromeda nebula, 439;
photographs of nebulæ, 493, 513;
measurement of stars in Orion nebula, 498;
hydrogen spectrum in nebulæ, 499, 502

Schiaparelli, colour of Sirius, 255

Schjellerup, red stars, 256–258;
observation of 55 Andromedæ, 466

Schmidt, A., optical theory of the sun, 165, 166

Schmidt, J., colour of Algol, 256;
low minimum of S Cancri, 306;
detection of a group of variables, 325;
fluctuations of ζ Geminorum, 328;
periodicity of υ Herculis and R Lyræ, 368;
minima of R Coronæ and of ε Aurigæ, 372

Schönfeld, period of R Lyræ, 368;
variable nebula, 528

Schultz, central star in Lyra nebula, 486

Schumann, constitution of Nova Aurigæ, 378

Schur, light-curve of η Aquilæ, 321;
catalogue of stars in Præsepe, 412

Schuster, spectral series, 53;
variations in the electrical conductivity of space, 158

Schwab, phases of U Sagittæ, 316

Schwabe, discovery of sun-spot period, 13

Schwarzschild, orbit of β Aurigæ, 291

Searle, invisibility of star in bi-annular nebula, 490

Secchi, darkening of sun’s limb, 70;
rosy veils in spot umbræ, 77;
eruptive hypothesis of solar constitution, 165;
localisation of stellar varieties, 173, 179, 181, 185, 186;
bright lines in fourth-type spectra, 185, 216;
spectrum of α Herculis, 211;
of “La Superba,” 217;
of γ Cassiopeiæ, 233, 249;
of β Lyræ, 338;
colours of double stars, 260, 261;
central star in Lyra nebula, 486;
annular nebula in Gemini, 493;
disappearance of Hind’s nebula, 523

See, evolution of double stars, 166, 333, 452;
elements of Sirius, 198;
colour of Sirius, 255;
double nebulæ, 452

Seeliger, selective absorption in the sun, 71;
solar refraction, 167;
encounter-hypothesis of Nova Aurigæ, 377;
theory of stellar outbursts, 379

Shackleton, photograph of flash spectrum, 19, 45

Sidereal physics, defined, 171;
an extension of solar physics, 172;
scope, 177;
connection with sidereal mechanics, 287

Sidgreaves, variable Fraunhofer-line, 37;
convexity of spot-umbræ, 80, 81;
observation of a prominence, 119;
rotation of faculæ, 146;
eruptive hypothesis of solar constitution, 165;
spectrographs of Mira, 185, 223;
of γ Cassiopeiæ, 187;
of β Lyræ, 339;
spectrum of Nova Aurigæ, 379;
of Nova Persei, 390, 391, 392

Silicon, a constituent of the sun, 27, 29;
of stars, 181, 182, 191, 193, 195, 198, 232

Sirius, silicon-absorption in, 193;
spectral character, 197, 200, 201;
mass and brightness, 198, 199;
colour in antiquity, 255, 256;
dusky satellite, 400

Smyth, Admiral, colours of double stars, 259, 260;
gold-dust cluster, 414;
a red satellite star, 464

Smyth, Piazzi, experiments on solar heat-radiation, 68;
colours of 95 Herculis, 260;
redness of η Carinæ, 370

Solà, Comas, triangulation of cluster in Sagittarius, 424

Solar physics, wide range of, 8;
definition, 13;
altered standpoint, 14;
methods and character of progress, 17, 20, 150;
illustrated by sidereal research, 172

Solar stars, characteristics, 182, 205;
transition from hydrogen stars, 203;
giant specimens, 205, 206;
minor orbs, 206, 207;
transition to Antarian stars, 207

Spectra, nebular, difficulty of investigating, 173, 174;
continuous, 439, 440;
gaseous, 475–480, 488, 491;
relative strength of constituent lines, 476, 479, 499–502;
of variable formations, 529

Spectra, stellar, local diversities, 173, 187, 196;
classification, 179–188;
banded, 179, 183, 184, 207, 209–220;
with bright lines, 185–188, 217–220, 222–235, 237–245, 407, 408;
variable, 227, 247–252;
anomalous, 246, 247, 251;
dissimilarly coupled, 263–268, 276;
relations to colour, 263, 270;
evolutionary succession, 271–278;
of Algol variables, 316;
of Cepheid variables, 327;
of Mira variables, 360;
of Novæ, 397;
of clusters, 413, 414;
free from nebular absorption, 532;
galactic types, 543

Spectrography, importance of, 3, 4, 38, 122, 234;
detection of binary systems by, 289;
applied to temporary stars, 376, 384, 385;
to clusters, 413;
to nebulæ, 439, 476, 502

Spectroscopic binaries, discoveries, 176, 289–298;
of dissimilar light-quality, 266, 295;
effects of rotation on, 283;
nature of evidence regarding their movements, 288;
classification, 289

Spectrum, solar, visible section, 21;
infra-red, 24;
photographic, 25;
thronged with absorption-lines, 36;
peculiarities, 37–42, 162;
telluric, 23, 24;
of oxygen, 28;
of helium, 29, 57, 58, 113, 114, 174;
of carbon, 31;
of reversing layer, 44–48;
of hydrogen, 52–54;
of coronium, 60, 130;
of sun-spots, 88–96;
of faculæ, 98, 100;
of chromosphere and prominences, 112–121, 163;
of the corona, 130–132, 163

Spectrum analysis, import of, to astronomy, 3;
to solar physics, 14

Sperra, light-change of S Antliæ, 331

Spica, a spectroscopic binary, 292

Spiral nebulæ, examples, 440–446, 487;
prevalence, 443;
explosive theory, 445;
simulate duplicity, 453

Spitaler, drawings of nebulæ, 456, 457, 458, 526;
measurements of nebulæ, 483;
invisibility of central star in Lyra nebula, 487

Spörer, shiftings of sun-spot zones, 151, 152

Star-clusters, globular, structural plan, 409, 428;
examples, 429–436;
non-nebulous, 433;
nests of variables, 434, 435, 436–438;
frequent the Milky Way, 448

Star-clusters, irregular, conformation, 409;
examples, 410–414;
nebulous, 423–427

Stars, classification, 179;
evolution, 271–279;
rotation, 280–285

Stefan, law of radiation, 64

Stellar nebulæ, limited to the Milky Way, 544

Stephan, nebulous star, 467;
discovery of a nebula, 479

Stone, Ormond, aspect of Orion nebula, 503;
varying brightness of contained stars, 504

Stoney, spectral series, 53;
escape of gases from planetary atmospheres, 55;
composition of photosphere, 63

Stratonoff, rotation of the sun, 83;
of faculæ, 145, 147;
counts of the Pleiades, 416;
nebulosities of the Pleiades, 418

Struve, O., division of γ Andromedæ, 266;
mass of η Cassiopeiæ, 268;
observation of bi-annular nebula, 490;
disappearance of a star in Orion nebula, 504;
discovery of a temporary nebula, 524

Struve, W., colours of double stars, 259, 261;
duplicity of Atlas, 421;
triplicity of 15 Monocerotis, 426

Sun, new views regarding, 14, 15;
appendages, 15;
chemistry, 18, 21, 25–34, 163;
spectral peculiarities, 36–43, 162, 163;
conformation, 62, 161;
general atmospheric absorption, 64, 65, 69, 70, 71;
radiation, 64, 65, 68, 151, 159;
temperature, 65–67, 69;
photospheric veil, 71, 72;
a bright-line star, 121, 154;
mode of rotation, 142–149, 161;
periodicity, 150–160, 162;
a variable star, 151, 362;
theories of constitution, 164–167;
a solitary body, 172, 282;
motion in space, 192, 415;
stage of development, 274

Sun-spots, periodicity, 3, 13, 150–152;
doubts regarding, 9, 86, 87;
spectra, 72, 88–97, 163, 195;
structural features, 73, 75–77;
relations to faculæ, 74, 161;
groupings, 77–79, 85;
question of level, 79–83, 86;
heat-emissions, 81, 82, 164;
movements, 83–85, 96, 142, 144;
dimensions, 85;
chemistry, 91;
scarcity in seventeenth century, 156;
magnetic relations, 154–158;
nature and origin, 162, 164;
refractive effects in, 167

Swift, black lines in prominences, 110;
nebulosity in Monoceros, 425;
hairline nebulæ, 442;
double nebulæ, 455, 457;
nebular groups, 458;
nebulous stars, 462, 463;
new features in Trifid and Omega nebulæ, 522;
observation of a variable nebula, 527

Sykora, measures of the sun’s diameter, 74

Tacchini, daylight extent of chromosphere, 109;
white prominences, 110, 120;
coronal relations of prominences, 129;
magnetic influences of the chromosphere, 157

Telluric absorption, 22–25

Tempel, discovery of Merope nebula, 416, 522;
drawing of a spiral nebula, 443;
Chacornac’s nebula, 523;
observation of Struve’s temporary nebula, 525

Temperature, of reversing layer, 49;
relations of to hydrogen spectrum, 54, 201;
in solar photosphere, 63–67, 69;
in sun-spots, 92, 96, 164;
in solar corona, 138, 140;
in stars, 193, 195, 199–201, 273, 274;
in nebulæ, 502, 535

Temporary nebulæ, 524, 526, 528, 529

Temporary stars, spectral character, 175, 397;
recent apparitions, 375–396;
photographic discoveries, 382–387;
summary of facts regarding, 396–398;
galactic proclivities, 396, 402, 543

Theodorus, observation of η Carinæ, 371

Thome, colour of η Carinæ, 371

Thomson, electrical affinities of hydrogen-lines, 112

Tisserand, disturbances of Algol, 305, 306;
of U Cephei, 310

Titanium, absorption by in the sun, 32, 49;
in spots, 91, 92;
in stars, 192, 193, 198, 226, 232;
bright lines of in flash and chromospheric spectra, 47, 118

Toucani, 47, globular cluster, 431, 436

Trapezium stars, composition of group, 230;
spectrum, 231, 232, 498, 532;
inconspicuously variable, 406;
photographed, 495;
proper motion, 497, 498

Trifid nebula, nuclear multiple star, 406, 510;
conformation, 509, 510;
spectrum, 510

Trouvelot, veiled spots, 102;
observations of prominences, 106, 110

Trowbridge, spectroscopic experiments, 34

Trowbridge and Hutchins, carbon in the sun, 32

Turner, photographs of the corona in polarised light, 132

Tuttle, discovery of a variable nebula, 527

Vanadium, a constituent of the sun, 32, 49;
of prominences, 119;
of Sirius, 198;
prominence of absorption in spot-spectra, 91, 92;
emission in γ Cassiopeiæ, 234, 249

Variable nebulæ, evasive of recognition, 522;
authentic examples, 523–528;
problem of, 529

Variable stars, solar analogy, 151, 176, 362, 406;
their helium emissions, 175, 226, 228;
open to research, 175, 176;
in clusters, 177, 319, 335, 336, 433–438;
with fourth-type spectra, 215, 358–360;
with bright-line fluted spectra, 222–228, 407;
with anomalous spectra, 246–248;
redness, 253–255, 352, 358;
of short period, 319–336, 404;
of long period, 347–362;
irregular, 363–374, 405;
correlation of spectrum and period, 406–408

Variable stellar spectra, an inexplicable phenomenon, 227;
examples, 247–252, 338, 339, 344

Vega, spectrographed, 182;
character of spectrum, 197, 198, 201;
remoteness, 200

Very, photospheric radiation, 67, 68;
nebulous formation round Nova Persei, 395

Vogel, H. C., spectrographic investigation of radial motion, 4;
solar atmospheric absorption, 70, 71;
helium stars, 174, 181;
stellar classification, 180, 277;
carbon stars, 184, 277;
fluted spectra, 211, 277;
spectrum of Mira, 223;
of a Wolf-Rayet star, 239;
of R Geminorum, 246;
of γ Cassiopeiæ, 248;
of β Cygni, 265;
of 95 Herculis, 267;
of Capella, 294;
of β Lyræ, 339, 344;
colour of γ Delphini, 260;
rotation of Altair, 281;
period of Mizar, 290;
duplicity of Spica, 292;
composition of Nova Aurigæ, 378;
radial motion of Nova Persei, 390;
structure of a planetary nebula, 471;
observations of annular nebulæ, 487, 490, 493;
invisibility of a nebula, 528

Vogel, H. W., fifth hydrogen-line, 52

Wadsworth, small apertures for nebular photography, 423, 496

Webb, colours of double stars, 259, 261;
discovery of a planetary nebula, 479

Weiss, coronal structure, 126

Wells, Miss, discovery of W Delphini, 315;
of S^2 Cygni, 366

Wendell, photometric measures of U Pegasi, 332

Wesley, study of, and drawings from coronal photographs, 125, 126, 134,
135

Wiedemann, effects of luminescence, 243, 397

Wilczynski, mode of solar rotation, 148

Williams, Stanley, discoveries of eclipsing stars, 316;
of V Puppis, 334

Wilsing, rotation of faculæ, 145;
of the sun, 148, 149;
absence of Hertzian vibrations in sunlight, 159;
luminescence of temporary stars, 397;
system of 61 Cygni, 403

Wilson, Alexander, perspective effects in sun-spots, 79, 80

Wilson, H. C., structure of Maia nebula, 417;
exterior Pleiades nebulosity, 419

Wilson, W. E., heat of sun-spots, 82;
nebula round Nova Persei, 395;
photographs of nebulæ, 444, 445, 484, 516

Wilson and Gray, determination of the sun’s temperature, 64, 65, 67;
variable radiation, 68

Wilson and Rambaut, arrest of heat in solar and terrestrial
atmospheres, 65, 69

Winkler, detection of germanium, 33

Winnecke, coronal observations, 123, 126;
measures of stars in Præsepe, 412;
variability of 15 Monocerotis, 425;
description of Webb’s nebula, 479;
indications of nebular variability, 528, 529

Wolf, C., map of the Pleiades, 421

Wolf, Max, photographs of galactic nebulosities, 205, 514;
of the place of Nova Aurigæ, 375;
of the Nova Persei nebula, 394;
of the Pleiades nebulosities, 418;
of planetaries, 482;
electrical rationale of Nova Persei nebula, 395;
photographic nebular survey, 449, 544;
a cluster of nebulæ, 458;
nebular distribution, 544, 545

Wolf, R., sun-spot and magnetic periods, 3, 154

Wolf-Rayet stars, metals unapparent in, 175;
spectrographs, 177;
galactic distribution, 187, 242, 543;
nature of spectra, 188, 237–240, 284;
affinities, 195, 217, 218, 246, 278, 440;
specimen with a hydrogen-envelope, 240, 241, 244;
stability in light, 406

Wolfer, solar rotation, 83, 147

Woods, eclipses of S Velorum, 314

Wright, orbit of η Aquilæ, 322;
spectrum of Nova Sagittarii, 385;
of Nova Aquilæ, 386

Yendell, orbit plane of Algol, 303;
light-change of d Serpentis, 335

Young, prominence photography, 18;
spectroscopic measurement of the sun’s rotation, 19, 283;
observation of reversing layer, 19, 44;
description of flash photograph, 45;
thermal variations of the sun, 67;
structure of sun-spots, 77;
their spectra, 88, 91, 93, 94;
helium absorption in, 94;
calcium in the sun, 114;
chromospheric spectrum, 119;
mode of solar rotation, 149;
eruptions in the sun, 165

Zeeman effect, described, 6;
possibly present in spectrum of Mira, 224

THE END

_Printed by_ R. & R. CLARK, LIMITED, _Edinburgh_

-----

Footnote 1:

Fowler, Introduction to _Novum Organum_, p. 38; _Descriptio Globi
Intellectualis_, chaps. v., vii.; _De Augmentis_, iii. 4.

Footnote 2:

_Astrophysical Journal_, vol. vi. p. 273.

Footnote 3:

_The Observatory_, vol. xx. p. 144.

Footnote 4:

The indications of this beautiful instrument, which depend upon the
changes of electrical resistance in a strip of platinum, produced by
differences of temperature, are believed to be reliable to
one-hundred-millionth of a degree centigrade. Langley, _Phil. Mag._
July 1901, p. 123.

Footnote 5:

_Proc. Royal Society_, vol. xlvi. p. 134.

Footnote 6:

_Journal de Physique_, t. x. p. 16.

Footnote 7:

Cortie, _Astronomy and Astrophysics_, vol. xi. p. 399.

Footnote 8:

_Trans. Royal Society of Edinburgh_, vol. xxxvi. part i.

Footnote 9:

_Phil. Mag._ August 1892.

Footnote 10:

A micron = one-thousandth of a millimetre.

Footnote 11:

_Annals of the Smithsonian Astrophysical Observatory_, vol. i. p. 170.

Footnote 12:

_Trans. Swedish Acad. of Sciences_, 1889; _Journ. de Physique_, t. x.
p. 141.

Footnote 13:

_Phil. Trans._ vol. clxxvii. p. 457.

Footnote 14:

_Ibid._ p. 462.

Footnote 15:

Wiedemann’s _Annalen_, Bd. xlvii. p. 208 (1892). See also E. P.
Lewis’s important investigations of “The Wave-Lengths of Infra-Red
Lines,” _Astr. Ph. Journal_, vol. ii. p. 1.

Footnote 16:

Published in its enlarged form in 1889.

Footnote 17:

_Die Spectralanalyse der Gestirne_, p. 177.

Footnote 18:

_Astrophysical Journal_, vol. ix. p. 214.

Footnote 19:

_Astr. and Astrophysics_, vol. xiii. p. 506.

Footnote 20:

_Comptes Rendus_, t. cxi. p. 431.

Footnote 21:

_Astr. and Astrophysics_, vol. xiii. p. 216.

Footnote 22:

Runge and Paschen, _Wiedemann’s Annalen_, Bd. lxi. p. 641 (1897).

Footnote 23:

_Astroph. Journ._ vol. iv. p. 317, vol. vi. p. 426. A second triplet
is also possibly present, but it is less obvious than the first.

Footnote 24:

_Astroph. Journ._ vol. vi. p. 101.

Footnote 25:

_Proceedings Royal Society_, vol. xxvii. p. 308.

Footnote 26:

_American Journ. of Science_, vol. xxxiv. p. 348.

Footnote 27:

Kayser and Runge, _Wied. Annalen_, Bd. xxxviii. p. 80; Crew and
Basquin, _Astroph. Journ._ vol. ii. p. 103.

Footnote 28:

Hartley, _Proc. Royal Society_, vol. lv. p. 348.

Footnote 29:

_Astroph. Journ._ vol. iv. p. 232.

Footnote 30:

_Ibid._ vol. v. p. 194.

Footnote 31:

Moissan, _Le Four Électrique_, pp. 257, 261.

Footnote 32:

_Journal Chemical Society_, 1887, vol. lv. p. 284.

Footnote 33:

Cleve, _Trans. Chem. Society_, 1895, p. 470.

Footnote 34:

_What is Electricity?_ p. 299.

Footnote 35:

_Amer. Journ. of Science_, vol. i. p. 331, 4th series.

Footnote 36:

_Astroph. Journ._ vol. i. p. 89.

Footnote 37:

_Ibid._ vol. x. p. 161.

Footnote 38:

R. A. Porter, _Astroph. Journ._ vol. xv. p. 281.

Footnote 39:

Fowler, _Knowledge_, vol. xxiii. p. 11.

Footnote 40:

_Astr. and Astrophysics_, vol. xi. p. 79.

Footnote 41:

Cortie, _ibid._ p. 591.

Footnote 42:

_Astroph. Journ._ vol. iii. p. 106.

Footnote 43:

_Astroph. Journ._ vol. iii. p. 157.

Footnote 44:

_Ibid._ pp. 92, 93.

Footnote 45:

_Astroph. Journ._ vols. iii. p. 114, iv. p. 175, vi. p. 169.

Footnote 46:

_Ibid._ vol. vi. p. 225.

Footnote 47:

_Astroph. Journ._ vol. xi. p. 240.

Footnote 48:

_Ibid._ vol. iii. p. 100.

Footnote 49:

_Astroph. Journ._ vol. iii. pp. 102, 103 (Jewell), p. 158 (Hale).

Footnote 50:

Jewell, _Astroph. Journ._ vol. xi. p. 236.

Footnote 51:

_Memoirs Royal Astr. Society_, vol. xli. pp. 339, 434 (Ranyard).

Footnote 52:

_Ibid._ p. 115.

Footnote 53:

_The Sun_, ed. 1897, p. 358.

Footnote 54:

Only the more refrangible parts of the portrayed spectra have been
reproduced. The complete images reach down to λ 6000 in the orange.

Footnote 55:

_Phil. Trans._ vol. cxcvii. A. p. 402.

Footnote 56:

S. A. Mitchell, _Astroph. Journ._ vol. xv. p. 118.

Footnote 57:

_Monthly Notices_, vol. lviii. p. 300 (Evershed).

Footnote 58:

Hale, _Astroph. Journ._ vol. iii. p. 160.

Footnote 59:

_Proc. Royal Society_, 17th Jan. 1901.

Footnote 60:

_Knowledge_, vol. ix. p. 50.

Footnote 61:

W. E. Wilson, _Proc. Royal Soc._ 12th Dec. 1901.

Footnote 62:

_Ibid._ vol. xxx. p. 93.

Footnote 63:

_Sitzungsberichte Berlin Acad. der Wiss._ March 1894.

Footnote 64:

_Comptes Rendus_, 9th July 1894.

Footnote 65:

_Publicationen des Haynaldschen Observatoriums_, Heft vi. p. 15, 1892.

Footnote 66:

See _Knowledge_, vol. ix. p. 49 (E. W. Maunder).

Footnote 67:

The third hydrogen line (Hγ), often called “G,” is adjacent to the
band at λ 431 named G by Fraunhofer.

Footnote 68:

_Wiedemann’s Annalen_, Bd. xxv. p. 80.

Footnote 69:

_Phil. Mag._ vol. xli. p. 294 (1871).

Footnote 70:

_Trans. Royal Soc. of Edinburgh_, vol. xxxii.

Footnote 71:

_Journ. Chem. Society_, vol. xliii. p. 390.

Footnote 72:

_Journ. de Physique_, t. v. p. 341 (1886).

Footnote 73:

_Phil. Trans._ vol. clxxiv. p. 187.

Footnote 74:

_Nature_, vol. lv. p. 200.

Footnote 75:

_Phil. Mag._ vol. xxix. p. 331; _Wied. Ann._ Bd. lii. p. 119.

Footnote 76:

_Ibid._ Bd. lxi. p. 641.

Footnote 77:

_Berlin Abhandl._ 1890

Footnote 78:

_Phil. Mag._ vol. xxx. p. 33 (1890).

Footnote 79:

_Astroph. Journ._ vol. v. p. 209.

Footnote 80:

_Ibid._ vol. v. p. 92; Kayser, _ibid._ pp. 95, 243.

Footnote 81:

Rydberg, _ibid._ vol. vi. p. 233.

Footnote 82:

Dewar, _Trans. Chem. Society_, 1898, p. 535.

Footnote 83:

_Astroph. Journ._ vol. vii. p. 25. The idea seems to have been
anticipated by Waterston in 1845. E. Rogovsky, _ibid._ vol. xiv. p.
251, _note_.

Footnote 84:

S. R. Cook, _ibid._ vol. xi. p. 36; but cf. Stoney, _ibid._ pp. 251,
357.

Footnote 85:

Rowland observed in his photographs some “thin haze,” which he
regarded as possibly due to diffuse absorption by four ultra-violet
hydrogen lines, but the connection is very doubtful. Huggins, _Atlas
of Stellar Spectra_, p. 150.

Footnote 86:

_Chemical News_, 29th March 1895; _Nature_, 19th December 1901.

Footnote 87:

_Nature_, 6th June 1895.

Footnote 88:

Their wave-lengths are λλ 7066, 5016, 4472, and 4026.

Footnote 89:

Lockyer, _Nature_, 3rd October 1895.

Footnote 90:

Runge and Paschen, _Nature_, 26th Sept. 1895; _Sitzungsberichte Berlin
Akad._ 20th June 1895; _Astroph. Journ._ vol. iii. p. 4; Maunder,
_Knowledge_, vol. xix. p. 285.

Footnote 91:

Ramsay and Collie, _Proc. Royal Society_, vol. lx. p. 56.

Footnote 92:

_Ibid._ vol. lix. p. 222.

Footnote 93:

See _Nature_, 17th and 24th May 1900 (Cook and Johnstone Stoney).

Footnote 94:

_Fifth Robert Boyle Lecture_, 2nd June 1895.

Footnote 95:

Ramsay, Collie, and Travers, _Journ. Chem. Society_, 1895, p. 697.

Footnote 96:

Collie and Ramsay, _Proc. Royal Society_, vol. lix. p. 264.

Footnote 97:

_The Sun_, p. 110, edit. 1897.

Footnote 98:

_Proc. Royal Society_, vol. xvi. p. 29.

Footnote 99:

Scheiner, _Strahlung und Temperatur der Sonne_, p. 27.

Footnote 100:

_Proc. Royal Society_, vol. lviii.

Footnote 101:

Young, _The Sun_, p. 302.

Footnote 102:

_Phil. Trans._ vol. clxxxv. p. 396.

Footnote 103:

_Phil. Mag._ vol. viii. pp. 324, 550.

Footnote 104:

_Wiedemann’s Annalen_, Bd. xxxix. p. 309.

Footnote 105:

_Proc. Royal Society_, 12th December 1901.

Footnote 106:

_Comptes Rendus_, t. cxiv. p. 737, 1892.

Footnote 107:

_Journ. de Physique_, t. vi. p. 474, 1887.

Footnote 108:

_Wied. Ann._ Bd. liii. p. 284, 1894.

Footnote 109:

_Astroph. Journ._ vols. ii. p. 202, x. p. 40, xi. p. 288.

Footnote 110:

_Ibid._ vol. ii. p. 57.

Footnote 111:

F. W. Very, _Astroph. Journ._ vol. ii. p. 317.

Footnote 112:

_Ibid._ vol. iv. p. 44.

Footnote 113:

The “solar constant” is the number of units of heat per unit of area
which would be received in unit of time by the earth’s surface if its
atmosphere were removed. The most approved value is three (small)
calories per square centimetre per minute, a “small” calorie being the
quantity of heat requisite to raise one gramme of water one degree
centigrade.

Footnote 114:

Hence Savélieff’s experiments, according to which the solar energy
progressively augmented with the increase in the number of spots in
the years 1890, 1891, and 1892, are suggestive rather than conclusive
(_Comptes Rendus_, t. cxviii. p. 62, and _Astroph. Journ._ vol. xiii.
p. 346).

Footnote 115:

_Astroph. Journ._ vol. vii. pp. 255, 264.

Footnote 116:

_Proc. Royal Irish Acad._ vol. ii. p. 299, third series.

Footnote 117:

_Monatsberichte_, Berlin, 1877, p. 104.

Footnote 118:

_Astroph. Journ._ vol. i. p. 261.

Footnote 119:

_Proceedings Amer. Acad. of Sciences_, 1880; _Amer. Journ. of
Science_, vol. xxi. p. 41, 1881.

Footnote 120:

_Strahlung und Temperatur der Sonne_, p. 49.

Footnote 121:

Vol. i. p. 74, 1902.

Footnote 122:

_Astr. Nach._ Nos. 3330, 3410.

Footnote 123:

Rev. W. Sidgreaves, _Astr. and Astrophysics_, vol. xi. p. 212.

Footnote 124:

_Astroph. Journ._ vol. v. p. 250; _Observatory_, vol. xxi. p. 404.

Footnote 125:

_Memoirs Royal Astr. Society_, vol. xli. p. 8 (Ranyard).

Footnote 126:

_Memoirs Brit. Astr. Ass._ vol. v. p. 84.

Footnote 127:

A. J. S. Adams, _Journ. Brit. Astr. Ass._ vol. iv. p. 203; E. Brown,
_ibid._ p. 300.

Footnote 128:

_The Sun_, p. 125.

Footnote 129:

_Il Sole_, p. 62, ed. 1884.

Footnote 130:

Suffusions of dark red matter were observed in the umbræ of a multiple
spot by E. S. Martin, 17th September 1893, _Popular Astronomy_, vol.
i. p. 91.

Footnote 131:

_Memoirs Brit. Astr. Ass._ vol. iv. p. 92.

Footnote 132:

Maunder, _Observatory_, vol. xxi. p. 403.

Footnote 133:

_Ibid._ p. 402, vol. xxiii. p. 233.

Footnote 134:

_Monthly Notices_, vol. lv. p. 73.

Footnote 135:

_Ibid._ vol. lviii. p. 91.

Footnote 136:

_Old and New Astronomy_, p. 382.

Footnote 137:

_Knowledge_, vol. xxi. p. 89.

Footnote 138:

_Astroph. Journ._ vol. vi. p. 91.

Footnote 139:

_Monthly Notices_, vol. lv. p. 282.

Footnote 140:

_Astroph. Journ._ vol. vi. p. 366.

Footnote 141:

_Astr. and Astrophysics_, vol. xi. p. 734; _Astroph. Journ._ vol. iv.
p. 201. Cf. J. Halm, _Annals Edin. Observatory_, vol. i. p. 145.

Footnote 142:

_Monthly Notices_, vol. lv. p. 458.

Footnote 143:

_Ibid._ vol. xxxvii. p. 5.

Footnote 144:

_Astr. and Astrophysics_, vol. xii. p. 739.

Footnote 145:

Frost, _Astroph. Journ._ vol. iv. p. 200.

Footnote 146:

_Journ. Brit. Astr. Ass._ vol. vii. p. 121.

Footnote 147:

Maunder, _Knowledge_, vol. xvii. p. 198.

Footnote 148:

_Observatory_, vol. xxiii. p. 230.

Footnote 149:

_Knowledge_, vol. xvii. p. 199.

Footnote 150:

Cortie, _Observatory_, vol. xxiii. p. 230.

Footnote 151:

_Recherches sur la Rotation du Soleil_, p. 12.

Footnote 152:

Young, _The Sun_, p. 132.

Footnote 153:

_Astr. and Astrophysics_, vol. xi. p. 242.

Footnote 154:

_Proc. Royal Society_, vol. xv. p. 257.

Footnote 155:

_Chemistry of the Sun_, p. 324.

Footnote 156:

_Ibid._ p. 319.

Footnote 157:

_Memoirs Royal Astr. Society_, vol. l. p. 50.

Footnote 158:

_Monthly Notices_, vol. lviii. p. 373.

Footnote 159:

Frost-Scheiner, _Astronomical Spectroscopy_, p. 177; J. S. Ames,
_Astroph. Journ._ vol. i. p. 89; Hartley, _Proc. Royal Society_, vol.
lvi. p. 192.

Footnote 160:

_Monthly Notices_, vol. xlvii. p. 19.

Footnote 161:

_Nature_, 12th Dec. 1872.

Footnote 162:

_Astroph. Journ._ vol. v. p. 248.

Footnote 163:

Gases glowing electrically in vacuum tubes were found by M. Cantor
incapable of absorption. But the results of further experiments must
be awaited before conclusions in so delicate a matter can be availed
of to elucidate the state of helium in the sun.

Footnote 164:

_Nature_, 12th Sept. 1895; _The Sun_, p. 134.

Footnote 165:

_Monthly Notices_, vol. lii. p. 424.

Footnote 166:

_Journ. Brit. Astr. Ass._ vol. ix. p. 253.

Footnote 167:

_Ibid._ vol. vii. p. 191.

Footnote 168:

_Astr. and Astrophysics_, vol. xi. p. 313.

Footnote 169:

Mascari, _Astroph. Journ._ vol. vi. p. 372.

Footnote 170:

_Astr. and Astrophysics_, vol. xi. pp. 159, 414.

Footnote 171:

_Comptes Rendus_, 8th Feb. 1892; _Knowledge_, vol. xvi. p. 230.

Footnote 172:

Deslandres, _L’Astronomie_, Dec. 1894.

Footnote 173:

Deslandres, _Comptes Rendus_, t. cxiv. No. ii.; _Journ. Brit. Astr.
Ass._ vol. ii. p. 237.

Footnote 174:

Evershed, _Astr. and Astrophysics_, vol. xi. p. 240.

Footnote 175:

_Amer. Journ. of Science_, vol. xi. p. 169 (1876).

Footnote 176:

_Publicat. Haynald Observatory_, Bd. vi. p. 40.

Footnote 177:

_Comptes Rendus_, 25th Jan. 1897.

Footnote 178:

_Astr. and Astrophysics_, vol. xiii. p. 124.

Footnote 179:

_Astroph. Journ._ vol. i. p. 212.

Footnote 180:

_Comptes Rendus_, t. ci. pp. 50, 475.

Footnote 181:

Trouvelot, _Bull. Astr._ t. iii. p. 21.

Footnote 182:

Fényi, _Astr. and Astrophysics_, vol. xii. p. 38.

Footnote 183:

Deslandres, indeed, observed velocities to become, as a rule,
accelerated in the upper sections of prominences (_Éclipse du 16
Avril, 1893_, p. 60); but this need not imply that they spring up in a
perfect vacuum.

Footnote 184:

_Astr. and Astrophysics_, vol. xi. p. 63.

Footnote 185:

H. H. Turner, _ibid._ p. 67.

Footnote 186:

Brester, _Théorie du Soleil_, p. 54.

Footnote 187:

Hale, _Astroph. Journ._ vol. iii. p. 377.

Footnote 188:

_Phil. Trans._ vol. clxxx. p. 345.

Footnote 189:

_L’Astronomie_, t. xii. p. 11.

Footnote 190:

_Lick Reports on Total Eclipse of 1st January 1889_, p. 204.

Footnote 191:

_Memoirs Royal Astr. Society_, vol. xli. p. 519 (Ranyard).

Footnote 192:

_Phil. Trans._ vol. cxc. p. 204 (Wesley).

Footnote 193:

_Bull. de l’Acad. Imp. des Sciences_, Mars 1897, p. 253.

Footnote 194:

Frost-Scheiner, _Astronomical Spectroscopy_, p. 189.

Footnote 195:

_Proc. Royal Society_, vol. lviii. p. 255.

Footnote 196:

Some American photographs taken during the eclipse of 28th May 1900
(_Astroph. Journ._ vol. xii. p. 63) show a brightening upward from the
limb, as if through increased rarefaction, of a few lines belonging to
green helium. This behaviour runs in the direction indicated by
vacuum-tube experience.

Footnote 197:

See _ante_, p. 60.

Footnote 198:

_Proc. Royal Society_, vol. lxvii. p. 467.

Footnote 199:

_The Chemistry of the Sun_, p. 194.

Footnote 200:

_Proc. Royal Society_, vol. lxi. p. 433. Besides H and K, _echoes_ of
them survive in a pair situated so high in the ultra-violet that they
can only be photographed with a specially adapted apparatus. Their
wave-lengths are λ 3179 and λ 3159. They may or may not be
chromospheric lines. The records so far obtained do not extend to
their remote position.

Footnote 201:

_Bulletin of the Yerkes Observatory_, No. 4, 1897.

Footnote 202:

_Observations de l’Éclipse Totale du Soleil du 16 Avril_, 1893, p. 64.

Footnote 203:

Hale, _Astroph. Journ._ vol. v. p. 225.

Footnote 204:

Evershed, _Nature_, 9th Sept. 1897.

Footnote 205:

_Astr. and Astrophysics_, vol. xi. p. 738.

Footnote 206:

_Ibid._ p. 430.

Footnote 207:

_The Indian Eclipse_, p. 70.

Footnote 208:

_Astroph. Journ._ vol. xi. p. 243.

Footnote 209:

_Ibid._ p. 165.

Footnote 210:

_Ibid._ vol. vi. p. 412.

Footnote 211:

_Ibid._ vol. x. pp. 112, 287.

Footnote 212:

_Astr. and Astrophysics_, vol. xi. p. 66.

Footnote 213:

_Astr. and Astrophysics_, vol. xi. p. 821.

Footnote 214:

_Proc. Royal Society_, vol. lxviii. p. 396.

Footnote 215:

See a valuable discussion by Hale, _Astroph. Journ._ vol. iii. pp.
374–387.

Footnote 216:

_Phil. Trans._ vol. cxcvii. A, p. 399.

Footnote 217:

_Astr. and Astrophysics_, vol. xi. p. 431; _Comptes Rendus_, 17th Aug.
1891 (Fényi).

Footnote 218:

_Astr. and Astrophysics_, vol. xiii. p. 119.

Footnote 219:

_Comptes Rendus_, 25th July 1892; _Knowledge_, vol. xvi. p. 146 (A. M.
Clerke).

Footnote 220:

_The New Astronomy_, p. 40.

Footnote 221:

_Memoirs Royal Astr. Society_, vol. xli. p. 563 (Ranyard).

Footnote 222:

_Publications Pacific Society_, vol. ii. p. 68.

Footnote 223:

_Memoirs Royal Astr. Society_, vol. xli. p. 656.

Footnote 224:

Ranyard, _ibid._ p. 652.

Footnote 225:

_Ibid._ p. 589 (Pope Hennessy).

Footnote 226:

Perrine, _Lick Bulletin_, No. 9.

Footnote 227:

Ranyard, _Memoirs Royal Astr. Society_, vol. xli. p. 687.

Footnote 228:

_Lick Reports_, p. 193.

Footnote 229:

_Phil. Trans._ vol. cxc. p. 204.

Footnote 230:

_Knowledge_, vol. xii. p. 145, 1889.

Footnote 231:

_Report on the Eclipse_, p. 96.

Footnote 232:

_Ibid._ p. 100; _Observatory_, vol. xvii. p. 350.

Footnote 233:

_Mémoires Acad. de St. Pétersbourg_, t. iv. p. 38, 1862.

Footnote 234:

_Memoirs Royal Astr. Society_, vol. xli. p. 602.

Footnote 235:

_The New Astronomy_, p. 55.

Footnote 236:

_Memoirs Royal Astr. Society_, vol. xlvi. p. 238.

Footnote 237:

Young, _The Sun_, p. 264.

Footnote 238:

_Bull. de l’Acad. de St. Pétersbourg_, t. vi. p. 286.

Footnote 239:

_Atti dell’ Accad. dei Lincei_, 1889, p. 763.

Footnote 240:

Schaeberle, _Report on the Eclipse of 16th April 1893_, pp. 92–98.

Footnote 241:

_Bull. de l’Acad. de St. Pétersbourg_, t. vi. p. 253, 1897.

Footnote 242:

_Nature_, vol. lix. p. 529.

Footnote 243:

_Astroph. Journ._ vol. x. p. 190.

Footnote 244:

S. J. Brown, _Astroph. Journ._ vol. xii. p. 63.

Footnote 245:

_Ibid._ p. 73.

Footnote 246:

Frost-Scheiner, _Astr. Spectroscopy_, p. 192; _Comptes Rendus_, t.
cxvii. p. 25.

Footnote 247:

_Astroph. Journ._ vol. xi. p. 232.

Footnote 248:

Schuster, _Monthly Notices_, vol. xl. p. 35.

Footnote 249:

_Observatory_, vol. xxi. p. 157.

Footnote 250:

Burnham and Schaeberle, _Report on Eclipse of December 1889_, p. 38.

Footnote 251:

_Bull. de l’Acad. de St. Pétersbourg_, t. iv. p. 275.

Footnote 252:

_Popular Astronomy_, vol. viii. p. 369.

Footnote 253:

_The Indian Eclipse_, p. 114.

Footnote 254:

_Ibid._ p. 118.

Footnote 255:

Wesley, _Knowledge_, Oct. 1900, p. 227.

Footnote 256:

Maunder, _Knowledge_, vol. xxi. p. 109. Cf. the visual observations of
Seagrave in 1900, _Astroph. Journ._ vol. xii. p. 99.

Footnote 257:

Hale, _Astr. and Astrophysics_, vol. xiii. p. 662.

Footnote 258:

_Observations de l’Éclipse du 16th Avril 1893_, p. 43.

Footnote 259:

_The Observatory_, vol. xxi. p. 188.

Footnote 260:

_Astroph. Journ._ vol. x. p. 186.

Footnote 261:

_Loc. cit._ p. 50.

Footnote 262:

_Total Solar Eclipse_, Dec. 1889, p. 47.

Footnote 263:

_The Indian Eclipse_, p. 121.

Footnote 264:

_Popular Astronomy_, p. 260 (edit. of 1878).

Footnote 265:

_Astroph. Journ._ vol. xii. p 25.

Footnote 266:

_Proc. Royal Society_, vol. xxxix. p. 108.

Footnote 267:

Deslandres, _loc. cit._ p. 62.

Footnote 268:

_The Solar Corona discussed by Spherical Harmonics_, 1889.

Footnote 269:

_Public. Pacific Society_, vol. iii. p. 216.

Footnote 270:

_Astr. and Astrophysics_, vol. xii. p. 804.

Footnote 271:

_Magnetic Fields of Force_, p. 73 (1897).

Footnote 272:

_Reports on Eclipse of 1st January, 1889_, p. 10.

Footnote 273:

_Bull. de l’Acad. des Sciences de St. Pétersbourg_, t. vi. March 1897.

Footnote 274:

_Astr. and Astrophysics_, vol. xi. p. 483.

Footnote 275:

_Amer. Journ. of Science_, vol. xi. p. 253, 1901.

Footnote 276:

_Annalen der Physik_, 1900, p. 462; quoted by G. F. Fitzgerald,
_Nature_, vol. lxii. p. 7.

Footnote 277:

_Comptes Rendus_, t. cxxx. p. 1691; _Nature_, 5th July 1900.

Footnote 278:

Bigelow, _Astr. and Astrophysics_, vol. xii. p. 823.

Footnote 279:

_Astr. and Astrophysics_, vol. xii. p. 825.

Footnote 280:

_History of Astronomy_ (A. M. Clerke), 4th edit. p. 202.

Footnote 281:

_Recherches sur la Rotation du Soleil_, p. 55.

Footnote 282:

_Potsdam Publ._ Bd. iv. pt. ii.; _Astr. Nach._ Nos. 3000, 3153, 3287.

Footnote 283:

_Astr. and Astrophysics_, vol. xii. p. 632.

Footnote 284:

_Astr. Nach._ Nos. 3275, 3344.

Footnote 285:

_Monthly Notices_, vol. lv. No. 1; _Astroph. Journ._ vol. xiv. p. 317.

Footnote 286:

See _ante_, p. 98.

Footnote 287:

_Vierteljahrsschrift Naturforsch. Ges. in Zürich_, Bd. xli. 1896.

Footnote 288:

_Astroph. Journ._ vol. iv. p. 138.

Footnote 289:

_Bull. de l’Acad. de St. Pétersbourg_, t. vi. No. 3, p. 293.

Footnote 290:

_Astr. Journ._ No. 416; _Astroph. Journ._ vol. iv. p. 101.

Footnote 291:

_Ibid._ vol. v. p. 37.

Footnote 292:

_Astr. Nach._ No. 3039; _Astroph. Journ._ vol. iii. p. 247.

Footnote 293:

_Memoirs Royal Astr. Society_, vol. li. p. 123.

Footnote 294:

_Astroph. Journ._ vol. iii. p. 248.

Footnote 295:

Cf. Halm, _Annals Edin. Observatory_, vol. i. p. 99, 1902.

Footnote 296:

Clerke, _Hist. of Astr._ pp. 148, 149, 4th ed.; Spoerer, _Potsdam
Publ._ Bd. x. part i. 1894.

Footnote 297:

_Knowledge_, vol. xv. p. 131.

Footnote 298:

Fényi, _Publ. Haynald Observ._ Bd. vi. p. 41.

Footnote 299:

Mascari, _Astroph. Journ._ vol. ii. p. 119; Evershed, _Astr. and
Astroph._ vol. xi. p. 426.

Footnote 300:

Mascari, _Astroph. Journ._ vol. vi. p. 371.

Footnote 301:

_Proc. Royal Society_, vol. lxiii. p. 64; _Monthly Notices_, vol. lx.
p. 142.

Footnote 302:

_Knowledge_, vol. xvii. p. 175.

Footnote 303:

_Ibid._ p. 206 (A. M. Clerke).

Footnote 304:

_Trans. Astr. Society of Toronto_, 1897, p. 80.

Footnote 305:

_Observatory_, vol. xiv. p. 328.

Footnote 306:

_Ibid._ vol. xv. p. 143.

Footnote 307:

Maunder, _Knowledge_, vol. xv. p. 89.

Footnote 308:

_Ibid._ p. 93.

Footnote 309:

_Astr. and Astrophysics_, vol. xi. p. 437.

Footnote 310:

_Ibid._ p. 925.

Footnote 311:

_Astr. and Astrophysics_, vol. xii. p. 717.

Footnote 312:

_Report Brit. Ass._ 1892, p. 634.

Footnote 313:

_Astr. Nach._ Nos. 2836, 2837.

Footnote 314:

_Nature_, vol. lxi. p. 445; vol. lxii. p. 460; _Astr. Nach._ No. 3619.

Footnote 315:

_Wiedemann’s Annalen_, Bd. lix. p. 782, 1896.

Footnote 316:

Bigelow, _Report on Solar and Terrestrial Magnetism_, p. 15.

Footnote 317:

_Astroph. Journ._ vol. iii. p. 112.

Footnote 318:

_Astr. and Astrophysics_, vol. xii. p. 740.

Footnote 319:

_Astr. and Astrophysics_, vol. xiii. p. 278.

Footnote 320:

_The Sun_, p. 187.

Footnote 321:

_Astr. and Astrophysics_, vol. xii. p. 833.

Footnote 322:

_Die Strahlenbrechung auf der Sonne_, Stuttgart, 1891.

Footnote 323:

_Monatsberichte_, Berlin, 1860, p. 405.

Footnote 324:

Knopf, _Astr. Nach._ No. 3199.

Footnote 325:

_Sirius_, 1893, p. 176.

Footnote 326:

_Astr. Nach._ No. 3187.

Footnote 327:

Frost, _Astroph. Journ._ vol. iv. p. 196.

Footnote 328:

_Ibid._ vol. xii. p. 185.

Footnote 329:

_Monatsberichte_, Berlin, 24th October 1895.

Footnote 330:

_Harvard Annals_, vol. xxviii. part i. 1897.

Footnote 331:

S. A. Mitchell, _Astroph. Journ._ vol. x. p. 32.

Footnote 332:

_Astr. and Astrophysics_, vol. xiii. p. 661.

Footnote 333:

This “short title” was first applied to them by Sir Norman Lockyer.
See _Nature_, 18th May 1899.

Footnote 334:

_Potsdam Publicationen_, No. 14, p. 26, 1884.

Footnote 335:

_Die Spectralanalyse der Gestirne_, p. 320.

Footnote 336:

Dunér, _Astroph. Journ._ vol. ix. p. 131.

Footnote 337:

_Astroph. Journ._ vol. x. p. 108.

Footnote 338:

_Astroph. Journ._ vol. viii. p. 233.

Footnote 339:

Campbell, _Astroph. Journ._ vol. ii. p. 181.

Footnote 340:

_Harvard Annals_, vol. xxviii. pp. 49, 93, 100, 142.

Footnote 341:

_Monthly Notices_, vol. lix. p. 507.

Footnote 342:

_Comptes Rendus_, t. lxxiv. p. 516.

Footnote 343:

Pickering, _Astroph. Journ._ vol. vi. p. 459.

Footnote 344:

_Astr. Nach._ No. 3025.

Footnote 345:

Campbell, _Astr. and Astrophysics_, vol. xiii. p. 474.

Footnote 346:

_Phil. Trans._ vol. cxci. p. 129.

Footnote 347:

Maury, _Harvard Annals_, vol. xxviii. p. 15.

Footnote 348:

_Abhandl. der kön. Sächs. Gesellschaft_, Bd. xv. Th. 1.

Footnote 349:

One taken 1st February is shown in _Knowledge_, vol. xix. p. 109.

Footnote 350:

_Astr. and Astrophysics_, vol. xiii. p. 178.

Footnote 351:

_Knowledge_, vol. xix. p. 39.

Footnote 352:

_Harvard Annals_, vol. xxxii. p. 66.

Footnote 353:

ε Orionis = N.G.C. 1990.

Footnote 354:

Barnard, _Pop. Astr._ Sept. 1897, p. 232.

Footnote 355:

_Spectra of Southern Stars_, p. 11.

Footnote 356:

_Proc. Royal Society_, 27th April 1899.

Footnote 357:

_Astr. and Astrophysics_, vol. xiii. p. 491.

Footnote 358:

_Astr. Nach._ Nos. 3565, 3583. Bellatrix was one of McClean’s original
oxygen stars.

Footnote 359:

_Nature_, vol. lxi. p. 263.

Footnote 360:

_Astroph. Journ._ vol. xi. p. 262.

Footnote 361:

_Ibid._ vol. x. p. 31 (Mitchell).

Footnote 362:

_Atlas of Stellar Spectra_, p. 152.

Footnote 363:

Scheiner, _Sitzungsberichte_, Berlin, 13th February 1890.

Footnote 364:

_Nature_, vol. lix. p. 342.

Footnote 365:

Hartley, _Astroph. Journ._ vol. x. p. 164.

Footnote 366:

_Astroph. Journ._ vol. ix. p. 267.

Footnote 367:

_Nature_, 16th March 1899.

Footnote 368:

Cf. A. Cotton on “Kirchhoff’s law,” _Astroph. Journ._ vol. ix. p. 244,
note.

Footnote 369:

Huggins, _Atlas of Spectra_, p. 148.

Footnote 370:

_Astr. Nach._ No. 3025.

Footnote 371:

_Spectra of Southern Stars_, p. 3.

Footnote 372:

A. C. Maury, _Harvard Annals_, vol. xxviii. p. 24.

Footnote 373:

Frost-Scheiner, _Astronomical Spectroscopy_, p. 243.

Footnote 374:

_Proc. Royal Society_, vol. xlviii. p. 216.

Footnote 375:

_The Sun’s Place in Nature_, p. 305.

Footnote 376:

_Sitzungsberichte_, Berlin, March 1894.

Footnote 377:

_Astr. and Astrophysics_, vol. xiii. p. 660.

Footnote 378:

_Harvard Annals_, vol. xxviii. p. 27.

Footnote 379:

A. C. Maury, _Harvard Annals_, vol. xxviii. p. 30.

Footnote 380:

_Astr. and Astrophysics_, vol. xii. p. 720.

Footnote 381:

_Phil. Trans._ vol. cxci. plate 6.

Footnote 382:

Fowler, _Knowledge_, vol. xx. p. 78.

Footnote 383:

_Harvard Annals_, vol. xxviii. p. 39.

Footnote 384:

_Astronomical Spectroscopy_ (Frost), p. 266.

Footnote 385:

_Harvard Annals_, vol. xxviii. p. 40.

Footnote 386:

Dunér, _Sur les Étoiles à Spectres de la Troisième Classe_, p. 9.

Footnote 387:

Thiele, _Astroph. Journ._ vol. viii. p. 1.

Footnote 388:

_Harvard Annals_, vol. xxviii. p. 42.

Footnote 389:

Frost-Scheiner, _Astr. Spectroscopy_, p. 308.

Footnote 390:

_Astroph. Journ._ vol. vi. p. 423.

Footnote 391:

_Potsdam Publicationen_, No. 14, p. 22.

Footnote 392:

_Spectra of Southern Stars_, Plate iv.

Footnote 393:

_Astroph. Journ._ vol. vi. p. 424.

Footnote 394:

The star was named _Ant-Ares_ (“like Mars”) because of its resemblance
to the planet in colour.

Footnote 395:

_Monthly Notices_, vol. lii. p. 154.

Footnote 396:

_Monthly Notices_, vol. lviii. p. 443.

Footnote 397:

_Astroph. Journ._ vol. x. p. 93.

Footnote 398:

Espin, _loc. cit._

Footnote 399:

_Astroph. Journ._ vol. ix. p. 132.

Footnote 400:

_Astroph. Journ._ vols. viii. p. 237, ix. p. 271, x. p. 87.

Footnote 401:

Hale, _First Annual Report_, p. 7. Spectrographs of 152 Schjellerup,
taken by McClean with two hours’ exposure, were described by him in
1897 as showing a multitude of dark lines.—_Monthly Notices_, vol.
lvii. p. 8.

Footnote 402:

_Astroph. Journ._ vol. viii. p. 239.

Footnote 403:

_Sugli Spettri Prismatici delle Stelle Fisse_, Mem. ii. 1869.

Footnote 404:

_Sur les Étoiles à Spectres de la Troisième Classe_, pp. 10, 82.

Footnote 405:

_Astroph. Journ._ vol. ix. p. 119.

Footnote 406:

_Ibid._ vol. x. p. 110.

Footnote 407:

_Astroph. Journ._ vol. x. p. 112.

Footnote 408:

_First Annual Report_, p. 8.

Footnote 409:

_Sur les Étoiles_, p. 45.

Footnote 410:

_Astroph. Journ._ vol. ix. p. 274.

Footnote 411:

They are catalogued in the southern zones of the Bonn Durchmusterung
as −10°5057 and −10°513.

Footnote 412:

Hale, _Astroph. Journ._ vol. viii. p. 239; Espin, _ibid._ vol. x. p.
170.

Footnote 413:

Sidgreaves, _Monthly Notices_, vol. lviii. p. 345.

Footnote 414:

_Sitzungsberichte_, Berlin, 26th March 1896.

Footnote 415:

_Monthly Notices_. vol. lviii. p. 344.

Footnote 416:

_Astroph. Journ._ vol. ix. p. 31; _Observatory_, vol. xxii. p. 152.

Footnote 417:

Krüger, _Astroph. Journ._ vol. ii. pp. 151, 158.

Footnote 418:

Keeler, _Lick Publ._ vol. iii. p. 225.

Footnote 419:

Espin, _Astr. Nach._ No. 2859.

Footnote 420:

Maunder believed it to be of fourth type, 1st Oct. 1888. _Monthly
Notices_, vol. xlix. p. 303.

Footnote 421:

_Astr. Nach._ No. 3765.

Footnote 422:

_Astroph. Journ._ vol. viii. p. 233.

Footnote 423:

_Astroph. Journ._ vol. ii. p. 178.

Footnote 424:

Runge, _Astr. Nach._ No. 3471.

Footnote 425:

Professor Frost’s conjecture that such stars may possess atmospheres
preferentially absorbent of the shorter radiations did not seem to
himself plausible enough for publication. _Astroph. Journ._ vol. ii.
p. 182. A similar explanation, however, has lately been recommended by
Dr. Kayser. _Ibid._ vol. xiv. p. 313.

Footnote 426:

_Astroph. Journ._ vol. ii. p. 181.

Footnote 427:

Evidently analogous is Hale’s result that the lines first reversed in
metallic spectra are the most refrangible. _Astroph. Journ._ vol. xv.
p. 227.

Footnote 428:

A. C. Maury, _Harvard Annals_, vol. xxviii. p. 104.

Footnote 429:

Keeler, _Astr. and Astrophysics_, vol. xiii. p. 486. The helium line,
λ 4472, is specially described. It is bright in the Orion nebula, dark
in all Orion stars.

Footnote 430:

Proc. _Royal Society_, vol. xlvi. p. 41.

Footnote 431:

Campbell, _Astr. and Astroph._ vol. xiii. p. 397.

Footnote 432:

_Comptes Rendus_, 11th Oct. 1897; _Astroph. Journ._ vol. vi. p. 322;
_Atlas of Spectra_, p. 138.

Footnote 433:

A. C. Maury, _Harvard Annals_, vol. xxviii. p. 104.

Footnote 434:

_Astroph. Journ._ vol. ii. p. 180.

Footnote 435:

A. C. Maury, _loc. cit._ pp. 49, 100.

Footnote 436:

Sidgreaves, _Monthly Notices_, vol. lix. p. 506.

Footnote 437:

_O Gyalla Beob._ Bd. vii. p. 14. For Keeler’s failure to perceive
D-absorption see _Publ. Pacific Society_, vol. i. p. 80.

Footnote 438:

_System of the Stars_, p. 70.

Footnote 439:

Bélopolsky, _Astr. Nach._ No. 3603; _Astroph. Journ._ vol. x. p. 319.

Footnote 440:

_Harvard Annals_, vol. xxviii. p. 175.

Footnote 441:

_Astr. Nach._ No. 2963.

Footnote 442:

_Astr. and Astroph._ vol. xiii. p. 158.

Footnote 443:

Frost, _Astroph. Journ. vol._ x. p. 365.

Footnote 444:

A. C. Maury, _loc. cit._ p. 104.

Footnote 445:

McClean, _Proc. Royal Society_, vol. lxii. p. 419.

Footnote 446:

_Astroph. Journ._ vol. iv. p. 369. For a list of analogous objects see
_Observatory_, vol. xxii. p. 54.

Footnote 447:

_Observatory_, vol. xxii. p. 52.

Footnote 448:

_Astr. and Astroph._ vol. xiii. p. 467.

Footnote 449:

_Astroph. Journ._ vol. ii. p. 177.

Footnote 450:

_Harvard Annals_, vol. xxviii. p. 247.

Footnote 451:

_Spectra of Southern Stars_, p. 15, Plate xii.

Footnote 452:

Campbell, _Astr. and Astroph._ vol. xiii. p. 449; _Astroph. Journ._
vol. ii. p. 178.

Footnote 453:

_Publ. Pac. Society_, vol. i. p. 81.

Footnote 454:

Hale, _Yerkes Observ. Report_, ii. p. 6.

Footnote 455:

_Potsdam Publ._ No. 14, p. 15.

Footnote 456:

_Astr. and Astroph._ vol. xiii. pp. 460, 468.

Footnote 457:

Campbell, _Astr. and Astroph._ vol. xiii. pp. 456, 468; Pickering,
_Astr. Nach._ No. 3025; Vogel, _Potsdam Publ._ No. 14, p. 17; A. J.
Cannon, _Harvard Annals_, vol. xxviii. pp. 147, 248.

Footnote 458:

Pickering, _Astr. Nach._ No. 2986.

Footnote 459:

_Astr. and Astroph._ vol. xiii. p. 461.

Footnote 460:

_Ibid._ vols. xii. p. 913; xiii. p. 461.

Footnote 461:

_Astr. Nach._ No. 3471.

Footnote 462:

_Astroph. Journ._ vol. viii. p. 113.

Footnote 463:

_Proc. Royal Society_, vol. xlix. p. 33.

Footnote 464:

Jewell, _Astroph. Journ._ vol. iii. p. 99.

Footnote 465:

_Astr. Nach._ No. 2000.

Footnote 466:

Frost-Scheiner, _Astr. Spectroscopy_, p. 323.

Footnote 467:

Argelander, _Astr. Nach._ No. 624.

Footnote 468:

_Monthly Notices_, vol. li. p. 12; Krüger, _Cat. der färbig. Sterne_,
p. 81.

Footnote 469:

_Astr. Nach._ No. 3200.

Footnote 470:

_Ibid._ No. 3633.

Footnote 471:

_Monthly Notices_, vol. li. p. 12.

Footnote 472:

_Cat. der färbig. Sterne_, p. 99.

Footnote 473:

_Bothkamp Beob._ Heft ii. p. 146.

Footnote 474:

Copeland, _Monthly Notices_, vol. xlvii. p. 92.

Footnote 475:

_Astr. Nach._ No. 2539.

Footnote 476:

_Proc. Royal Society_, vol. lvii. p. 174.

Footnote 477:

_Monthly Notices_, vol. lix. p. 505.

Footnote 478:

_Sugli Spettri Prismatici delle Stelle_, Mem. ii. 1868.

Footnote 479:

Frost-Scheiner, _Astr. Spectroscopy_, p. 256.

Footnote 480:

Lockyer, _Proc. Royal Society_, vol. lvii. p. 173.

Footnote 481:

_Publ. Pacific Society_, vol. i. p. 80.

Footnote 482:

_Astr. Nach._ No. 3129.

Footnote 483:

A. C. Maury, _Harvard Annals_, vol. xxviii. pp. 124, 126.

Footnote 484:

_O Gyalla Beob._ Bd. vii. p. 14.

Footnote 485:

_Harvard College Circular_, No. 32; _Annals_, vol. xxviii. p. 183.

Footnote 486:

_Harvard Circular_, No. 32.

Footnote 487:

_Ibid._ No. 21; _Annals_, vol. xxviii. p. 184.

Footnote 488:

_Astroph. Journ._ vol. ii. p. 180.

Footnote 489:

_Fifty-fifth Harvard Report_, p. 10; _Harvard Circular_, No. 60;
_Annals_, vol. xxviii. pp. 180, 183.

Footnote 490:

Fleming, _Monthly Notices_, vol. liii. p. 275; _Harvard Circular_, No.
4.

Footnote 491:

_Astroph. Journ._ vol. i. p. 411.

Footnote 492:

_Harvard Circular_, No. 32.

Footnote 493:

Fleming, _Astr. Nach._ No. 3054; _Astr. and Astrophysics_, vol. xi. p.
27.

Footnote 494:

_Astroph. Journ._ vols. x. p. 365; xvi. p. 114.

Footnote 495:

A. C. Maury, _Harvard Annals_, vol. xxviii. p. 104.

Footnote 496:

_Astr. and Astrophysics_, vol. xi. pp. 269, 372, 550.

Footnote 497:

_Atti dell’ Accad. degli Agiati_, t. ii. 1896.

Footnote 498:

_Astr. Nach._ No. 1099.

Footnote 499:

Krüger, _Cat. der färbig. Sterne_, p. 9.

Footnote 500:

Known as “64 _b_ Schjellerup” = Krüger 513. See _Cat. der färbig.
Sterne_, p. 33.

Footnote 501:

No. 6803 of the _Copenhagen Catalogue_ = 214 Schjellerup = Krüger
1436.

Footnote 502:

Krüger 504.

Footnote 503:

Binary in slow motion (Innes). Composite spectrum (A. J. Cannon).

Footnote 504:

S.D.M. −10° 513 and S.D.M. −10° 5057 of eighth and seventh magnitudes
respectively.

Footnote 505:

_Mensuræ Micrometricæ_, p. lxxxi.

Footnote 506:

_Intellectual Observer_, vol. ii. p. 138, 1863.

Footnote 507:

_Annales de l’Observatoire de Nice_, t. ii.

Footnote 508:

Webb, _Celestial Objects_, 4th ed., p. 297; _Knowledge_, vol. xiii. p.
250.

Footnote 509:

_Astr. Nach._ No. 3023.

Footnote 510:

_Journ. Brit. Astr. Ass._ vol. v. p. 457.

Footnote 511:

_System of the Stars_, p. 159.

Footnote 512:

_Les Étoiles_, p. 690.

Footnote 513:

Webb, _Cel. Objects_, vol. ii. p. 182.

Footnote 514:

Burnham, _Astr. Nach._ Nos. 2875, 3114.

Footnote 515:

A. C. Maury, _Harvard Annals_, vol. xxviii. pp. 93, 99.

Footnote 516:

_The Observatory_, vol. xxii. p. 387.

Footnote 517:

_Phil. Trans._ vol. cliv. p. 431.

Footnote 518:

_Bothkamp Beob._ Heft ii. p. 28.

Footnote 519:

_Astr. Nach._ No. 3034.

Footnote 520:

_Harvard Annals_, vol. xxviii. p. 93.

Footnote 521:

A. C. Maury, _Harvard Annals_, vol. xxviii. pp. 92, 100.

Footnote 522:

Leavenworth, _Publ. Leander M‘Cormick Observatory_, vol. i. pt. iv. p.
96.

Footnote 523:

A. C. Maury, _Harvard Annals_, vol. xxviii. pp. 17, 119.

Footnote 524:

Pickering, _Astroph. Journ._ vol. vi. p. 350.

Footnote 525:

Huggins, _Atlas of Spectra_, p. 164, plate xii.; Bélopolsky, _Astr.
Nach._ No. 3510.

Footnote 526:

_Astroph. Journ._ vol. viii. p. 307.

Footnote 527:

_Nature_, vol. lx. p. 249.

Footnote 528:

Maunder, _Knowledge_, vol. xiv. p. 73.

Footnote 529:

_Astroph. Journ._ vol. vi. p. 326.

Footnote 530:

_Atlas of Spectra_, p. 160.

Footnote 531:

_Monthly Notices_, vol. xxxvii. p. 278. The difficulties in applying
the theory were pointed out by Vogel, _Astr. Nach._ No. 2141.

Footnote 532:

Scheiner, _Astr. Nach._ No. 2924; _Potsdam Publ._ Bd. vii. p. 232.

Footnote 533:

_Comptes Rendus_, t. cxxi. p. 629.

Footnote 534:

_Sitzungsberichte_, Berlin, 17th Nov. 1898.

Footnote 535:

_Astr. and Astrophysics_, vol. xii. p. 719.

Footnote 536:

_Phil. Trans._ vol. clxxxiv. p. 696.

Footnote 537:

_Atlas of Spectra_, Plate ix.

Footnote 538:

_Atlas of Spectra_, p. 69.

Footnote 539:

_Comptes Rendus_, t. cxxi. p. 629.

Footnote 540:

The method usually employed is that given by Lehmann-Filhés, _Astr.
Nach._ No. 3242.

Footnote 541:

A. C. Maury, _Astroph. Journ._ vol. viii. p. 174.

Footnote 542:

_Harvard Annals_, vol. xxvi. p. xviii.; _Harvard Circular_, No. 11;
_Astr. Nach._ No. 3017; _Monthly Notices_, vol. l. p. 297.

Footnote 543:

_Sitzungsberichte_, Berlin, 2nd May 1901; _Astroph. Journ._ vol. xiii.
p. 324.

Footnote 544:

_Astr. Nach._ No. 3456.

Footnote 545:

_Comptes Rendus_, t. xiii. p. 438; quoted by Gore, _Knowledge_, vol.
xxii. p. 201.

Footnote 546:

_Monthly Notices_, vol. li. p. 316.

Footnote 547:

_Astr. Nach._ No. 3242.

Footnote 548:

_Ibid._ No. 3629.

Footnote 549:

Vogel, _ibid._ No. 3017.

Footnote 550:

_Astroph. Journ._ vol. viii. p. 173.

Footnote 551: