THE PHYSICS OF THE MILKY WAY.
The Milky Way is an integral part of the great sidereal system. It marks
the equatorial girdle of a sphere containing stars and nebulæ variously
scattered and aggregated. The whole material creation is, to our
apprehension, enclosed within this sphere. We know nothing of what may
lie beyond. Thought may wander into the void, but observation cannot
follow. And where its faithful escort halts, positive science comes to a
standstill. Fully recognising the illimitable possibilities of
Omnipotence, we have no choice but to confine our researches within the
bounds of the visible world. That it _has_ bounds is evident from the
consideration that it possesses shape and parts. Indefinitely extended,
star-filled space could have neither. Hence it offers to the human mind
an intelligible problem—a problem perhaps too intricate for definitive
solution, yet coming well within range of attack. The siege operations
may be protracted through many a campaign; but in conducting them we
shall climb from peak to peak of the Alpine chain of truth, and gain
continually wider views of the majestic scene that encompasses and
enchants us.
The structural relations of the cosmos may evidently be looked at from
many sides; our immediate concern is with but one of its aspects. We
have only to consider the nature of the materials used for the building
of the edifice and the plan of their apportionment to its different
sections. These materials consist of gaseous and white nebulæ in all
their varieties; of star clusters, globular and irregular, and of the
sundry species of stars; and even a cursory inspection shows that they
are not piled together at random. Each class, on the contrary, obeys its
own law of distribution; and the distribution of sidereal, as of animal
species, is the outcome of their history, a test of their longevity, an
index to their nature. They are _where_ they are, because they are
_what_ they are.
There seemed, twenty years ago, very little reason to anticipate that
the photographic method could ever be used to advantage for
investigating the physics of the Milky Way; yet it has, especially in
Professor Barnard’s hands, proved most effective in that difficult
branch of inquiry. The requisites were peculiar. The galactic drifts are
made up of very small stars—usually of fourteenth to sixteenth
magnitude, or even fainter,—and the sensitive plate perceives them, not,
as the human eye does, collectively, merged into a nebulous surface, but
one by one as light-points. Hence their rays need to be powerfully
concentrated in order to make any chemical effect with a moderately long
exposure. Moreover, the field must be large enough to show the colossal
forms into which these stellar units are grouped. For each picture a
canvas of at least 100 square degrees must be available. Hence
telescopes of the ordinary type, however powerful, are, for this
purpose, entirely useless. An ordinary village photographer’s apparatus
would be better adapted to it. Professor Barnard obtained his remarkable
series of delineations with the “Willard lens,” a doublet of six inches
aperture and thirty-one focal length, constructed at New York in
1859.[1179] They extend over a large part of the Milky Way, but leave
lacunæ, the filling up of which should be the diploma-performance of the
new Bruce lens. It might indeed be supposed that a few specimen
sky-scapes in galactic regions would suffice to afford practical
acquaintance with the entire round; but this is very far from being the
case. No feature of the Milky Way is more surprising than its
inexhaustible variety. No “law of condensation,” such as prevails in
globular clusters, is there traceable. Each section follows its own
method of aggregation. In one, cloud-forms are met with of the cirrus
type; in another, they recall breaking waves or tossing spray;[1180]
again, groups of irregular bright spots alternate with extensive
ramifications and rifts; here the starry fabric is coarse-grained, there
of microscopic fineness; while for heterogeneous scattering in many
quarters, there is substituted in others an apparently designed
arrangement of the stars into rings, chains, and ellipses.
Barnard’s photograph in Ophiuchus, reproduced in Plate XXXI., has
characteristics demanding earnest attention. The bright star below the
middle of the plate encircled by a halation ring is θ Ophiuchi, an
object spectrally akin to Bellatrix, radiantly white and marked by
helium absorption. A “long, dull vacancy,” visible to the naked eye,
stretching east and west below (south of) Theta, comes out as “an
irregular rift in the sheeting of stars,” of highly complex relations.
It circuits the east as well as the north and south sides of the bright
mass in which the star is placed, breaks up to the north into scattered
dark openings, and straggles on to the western edge of the plate,
whence—as other photographs of the series show—it communicates with some
of “the great vacant lanes” in the “wonderful nebulous region about ρ
Ophiuchi.”[1181] The most singular feature, however, of the galactic
chasms visible in our figure is the presence in them of two gradations
of obscurity. Darker details can be made out on the dark background,
recalling the analogy (which did not escape Professor Barnard’s notice)
of the “black holes” in the umbræ of active sun-spots. The conviction
was thus, he added, almost enforced that the Milky Way rests here upon a
far-reaching stratum of nebulous, or quasi-nebulous matter.
[Illustration:
PLATE XXXI.
Photograph of the Milky Way in Ophiuchus (Barnard).
]
The reality, the frequency, and the determinateness of the black
openings in the Milky Way, dimly seen with the naked eye, constitute one
of the most important facts regarding the nature of that formation
attested by the camera. It is true that their great exemplar in the
southern heavens—the “Coalsack” in Crux—seemed, in a photograph taken by
Dr. Russell of Sydney, 13th August 1890, to be embroidered with small
stars over three-fourths of its area;[1182] but this is an unessential
trait of the phenomenon. The fundamental circumstance connected with it
is the extensive and complete perforation of the dense galactic stratum
lying behind the starry network; and of this stratum there is no trace
in the Sydney picture. Only the foreground of the scene is delineated in
it; the backward stretching ranges remained inaccessible with the means
employed. The true Coalsack, then, has not yet been photographed, and we
are ignorant of the precise form which it will take upon the sensitive
plate. The exposures made at Lick, however, effectively reached the
piles of luminous dust which form the ultimate reality of the Milky Way,
and brought into view with insistent clearness the pits and furrows of
almost absolute darkness by which they are frequently interrupted. One
is perpetually reminded, in looking at these autographic records, of
Herschel’s exclamation of amazement when his telescope plunged suddenly
into an unfathomable abyss in Scorpio: _Da ist wahrhaftig ein Loch im
Himmel!_
Now “holes” of the kind have a very wide cosmical significance. The
great rift, by which the entire galactic structure is divided throughout
one-third of its circumference, is only a magnification of innumerable
cracks and fissures yawning amid its component star-masses. And the dark
lanes in globular clusters are plainly of kindred origin. Moreover, the
riddled aspect of the Milky Way in certain of its sections is
continually reproduced both in nebulæ and clusters—in nebulæ, whether
gaseous or stellar, as well as in diverse species of clusters. The fact
is a general one, that in all the forests of the universe there are
glades and clearings. How they come to be thus diversified we cannot
pretend to say; but we can see that the peculiarity is structural—that
it is an outcome of the fundamental laws governing the distribution of
cosmic matter. Hence the futility of trying to explain it as of
incidental origin, as a consequence, for instance, of the stoppage of
light by the interposition of obscure bodies, or aggregations of bodies,
invisibly thronging space. That dark stars exist, singly and in systems,
and dark nebulæ no less, we have been almost inevitably led to conclude;
but the galactic clefts cannot be reckoned among their manifestations.
They are, on the contrary, what they appear to be, intervals of starless
space between neighbouring star-clouds, and suggest processes of
disintegration[1183] advancing with inconceivable slowness towards
unimagined issues. These wonderful collections are then in a state of
flux; they are passing from one condition to another; Supreme Power is
at work in dispersing or refashioning them, sending abroad their
aggregated suns like flying sparks from the anvil.
But are those sparks indeed suns on the scale of our own? The answer
to be given depends upon our estimate of their average distance. They
are undoubtedly very remote. It may be taken as certain that they lie
beyond the sphere occupied by the Durchmusterung stars—that is, by the
ordinarily distributed stars of our system down to 9·5 magnitude. How
much farther beyond, we are, however, unable to say. The thronging
orbs of the Galaxy are by no means of uniform brightness. A recent
inquirer[1184] concludes that they range from the sixth to the
sixteenth magnitude; and the statement, which probably falls short of
the truth, implies that stars enormously disparate in apparent lustre
are at sensibly the same distance from ourselves; hence, that the
crowd of small or medium-sized bodies collected in the Milky Way are
dominated by veritable giants, more sparingly distributed. Professor
Barnard endeavours to bring this state of things into conformity with
received standards by levelling down the dimensions of galactic
constituents.[1185] To the ruck of them he assigns scarcely more than
planetary rank, so as to escape the necessity of admitting fabulous
magnitudes for their leaders. But in truth we have no means of fixing
a scale for such valuations. We know that there are suns hundreds,
even thousands, of times larger than the sun. Why should there not be
others larger still in a similar proportion? _Non est naturæ mensura
hominis electio_, Kepler wrote to Herwart in 1599. Our estimates are,
in many cases, minimum values; we can place no upper limit to the
vastness of the orbs of space. It is only safe to affirm that the
greatest and the least of them are associated and conjoined in the
immense aggregations of “this gorgeous arch, with golden worlds
inlaid, built with Divine ambition.”
The sidereal tribes are very differently affected towards the central
plane of the system. Some, as it were, deliberately withdraw from it;
others are exclusive in their preference for it; many press towards it,
while maintaining a cosmopolitan status. That white stars largely
preponderate in the Milky Way, is a fact made evident by Kapteyn’s
discussion of the Cape Durchmusterung photographs.[1186] It might,
nevertheless, as Mr. Monck of Dublin first noted, be due to their
superior areal brilliancy, which would cause them, with increase of
distance, to come into view preferentially, and at last exclusively. The
percentage of white stars must, indeed, apart from very unlikely
specialties of distribution, augment among the lower magnitudes, since a
star emitting light of the Sirian quality would appear equally bright
when fully twice as far off as one of the same size clothed with a solar
atmosphere. Moreover, Kapteyn’s researches did not extend below the
tenth magnitude, and the genuine galactic particles are of much lower
grades of brightness. So that the nature of their spectra has not, up to
the present, been disclosed to us. Yet a surmise regarding it may be
hazarded. Mr. McClean perceived the bright helium stars included in his
survey to be disproportionately numerous in the Milky Way zone. This is
probably one among several symptoms of their great remoteness. They are
sufficiently removed, perhaps, from the centre of the sidereal sphere to
come within the sweep of the current of tendency setting in towards its
equatorial regions. How it seems probable that fainter specimens of the
type are similarly, but more strongly condensed; and a further step on
the tempting road of conjecture leads us to the inference that the dim
aggregations girdling the heavens are mainly composed of stars of the
Orion family—of stars reversing the duplicate series of hydrogen lines,
besides those of oxygen, helium, nitrogen, and silicon.
We have seen in an earlier chapter that the Milky Way is the chosen
resort of Wolf-Rayet stars. They doubtless belong to it intimately and
entirely; and the same may be said of Novæ. This involves the strange
consequence that, amid the radiant galactic hordes, there must circulate
a multitude of large obscure bodies, fitted on occasion to blaze into
sudden conflagration, on a scale startling to intelligent beholders in
every quarter of the universe. Must we then conclude that dark stars are
relatively more plentiful in the Milky Way than elsewhere? Not
necessarily, perhaps, for its scarcely infringed monopoly in the
production of temporary stars might be explained equally well by the
virtual limitation to it of the conditions needed for luminous
explosions, as by the abundance in it of their appropriate fuel.
Very few gaseous nebulæ have any considerable galactic latitude; they
are characteristically Milky Way objects. There are, indeed, exceptions.
Some noted planetaries—those in Draco and Ursa Major for example—are
situated far outside the zone of concentration, and they present the
appearance of being nearer to the earth than most members of the class.
The “stellar” variety, on the other hand, which are presumably small
through remoteness, are, to the best of our knowledge, limited to the
Milky Way; while irregular nebulæ occur either in the main stream or in
some of its affluents. Among these the Magellanic Clouds are, in a
sense, to be counted, though they should rather be described as pools,
left behind as the waters contracted into their present bed. They are
composed, like the Milky Way, of mixed ingredients, stellar and
nebulous; they seem to reproduce its condition; they bear the same
primitive stamp. Their globular shape, however, suggests an autonomous
constitution, each being probably a self-regulated body; while the
galactic aggregations may be supposed exempt from the efficient control
of a central authority. Dr Russell’s photographs disclosed spiral
tendencies in the Nubeculæ,[1187] destined perhaps to become more and
more pronounced with time.
Through the agency of the portrait-lens and the sensitive plate, the
nebulous affinities of the Milky Way have been more fully recognised
than was possible by visual means alone. Several of Professor Barnard’s
pictures exhibit an intermixture of vaguely diffused lucid matter with
layers of minute stars, especially in parts of Cygnus, Cepheus, Perseus,
Monoceros, and Scorpio. We see, then, that the great cosmic zone is not
only frequented by nebulous objects, but is nebulous in itself. Yet it
seems to repel from it the multitude of white nebulæ which tend to
collect about its poles. This, at least, is the law of their visual
distribution; but the camera threatens to abrogate it. Dr. Max Wolf
holds that the results of his preliminary photographic surveys prove
nebulæ to be in reality scattered pretty evenly over the heavens. Only
their average brightness, he thinks, varies, the so-called “nebular
regions” in Cetus and Virgo having acquired their reputation as such not
because nebulæ are more numerous, but because they are there more
conspicuous than in the intervening celestial tracts. The subject, in
fact, of nebular distribution, which had been supposed practically
disposed of, has been, by photographic explorations, reopened for fresh
discussion.
The crowding of globular clusters upon the Milky Way is unmistakable;
and the inwardness of their relation to its condensations is manifested
by their avoidance of the vacuous rifts, and their adherence to the
stream-lines of luminosity. Hence arises the logical necessity for their
radical separation from white nebulæ, to which they seem, in most
respects, so near akin that one might be led to believe mere difference
of distance to occasion the distinction between resolvable and
irresolvable objects. Only the opposite galactic proclivities of the two
classes decisively place them apart.
Within sight of that ultimate problem, the structure of the sidereal
universe, we pause. Our thoughts meet, but they cannot grapple with it;
nor does it come within the scope of our present purpose to make the
attempt. We must be content to register the marks of growth and change
legible in the Milky Way; to note the evidence of its comparatively
recent origin and inchoate state; to avow our impotence to comprehend
the Supreme design which it is directed to realise; and to bend in awe
and admiration before the unfathomable depths of difficulty and mystery
towards which the study of sidereal development, in its larger bearings,
inevitably leads. _Die Schöpfung_, as Kant discerned, _ist niemals
vollendet_. _Sie hat zwar einmal angefangen, aber sie wird niemals
aufhören._
APPENDIX
TABLE I
STARS WITH VARIABLE SPECTRA
┌───────────────┬────┬───────────────┬────────────────────────────────┐
│ Name of Star. │Mag.│Position, 1900.│ Remarks. │
├───────────────┼────┼──┬──┬─────────┼────────────────────────────────┤
│ „ │ „ │R.│A.│ Dec. │ „ │
├───────────────┼────┼──┼──┼─────┬───┼────────────────────────────────┤
│ │ │h.│m.│ │ │ │
│γ Cassiopeiæ │ 2·3│ 0│51│+ 60°│10′│Hα usually brilliant; at times │
│ │ │ │ │ │ │ invisible. D_{3} │
│ │ │ │ │ │ │ intermittently bright. Further│
│ │ │ │ │ │ │ variations apparent. │
│8 Schjellerup │ 7·2│ 1│12│+ 47°│ 9′│Spectrum continuous, 14th │
│ │ │ │ │ │ │ November 1887; fluted, 6th │
│ │ │ │ │ │ │ October 1891. │
│ο Ceti │var.│ 2│14│− 3°│26′│Hγ and Ηδ triple, 29th August; │
│ │ │ │ │ │ │ single, 6th November 1898. │
│ │ │ │ │ │ │ Iron (?) line at λ 4308, dark │
│ │ │ │ │ │ │ at maxima of 1896 and 1897, │
│ │ │ │ │ │ │ bright in 1898. │
│ψ Persei │ 4·2│ 3│29│+ 47°│52′│Bright Ηβ shifts capriciously │
│ │ │ │ │ │ │ from one to the other side of │
│ │ │ │ │ │ │ a broad absorption-band, on │
│ │ │ │ │ │ │ which it is normally central │
│ │ │ │ │ │ │ (A. C. Maury). │
│11 Monocerotis │ 4·7│ 6│24│ − 6°│58′│Bright Ηβ less refrangible in │
│ │ │ │ │ │ │ 1888–90, more refrangible in │
│ │ │ │ │ │ │ 1891–2 than dark Ηβ. │
│A.G.C. 9181 │ 5·4│ 7│10│− 26°│10′│Ηβ and Hγ vary from dark to │
│ │ │ │ │ │ │ bright, not always in concert │
│ │ │ │ │ │ │ (A. J. Cannon). │
│J Velorum │ 4·4│10│17│− 55°│33′│Ηβ and Hγ intermittently bright │
│ │ │ │ │ │ │ (A. J. Cannon). │
│A.G.C. 14,686 │ 7·0│10│40│− 59°│ 1′│H · lines alternately bright and│
│ │ │ │ │ │ │ dark (_Harvard Circular_, No. │
│ │ │ │ │ │ │ 32). │
│η Centauri │ 2·5│14│29│− 41°│43′│Composite spectrum, subject to │
│ │ │ │ │ │ │ intricate changes, partly │
│ │ │ │ │ │ │ explicable relative │
│ │ │ │ │ │ │ motion-shifts of bright and │
│ │ │ │ │ │ │ dark Ηβ (A. J. Cannon). │
│κ′ Apodis │ 5·6│15│21│− 73°│ 2′│Ηβ variably bright (A. J. │
│ │ │ │ │ │ │ Cannon). │
│R Coronæ │var.│15│44│+ 28°│28′│Spectrum at times continuous, at│
│ │ │ │ │ │ │ times banded. Bright lines │
│ │ │ │ │ │ │ occasionally visible. │
│214 Schjellerup│ 7·0│18│28│− 5°│13′│Spectrum third type, 1889; │
│ │ │ │ │ │ │ second type, 1892. │
│R Scuti │var.│18│42│− 5°│49′│Type III.; bands effaced at │
│ │ │ │ │ │ │ maxima. Unidentified bright │
│ │ │ │ │ │ │ lines recorded by Espin in │
│ │ │ │ │ │ │ 1890. │
│β Lyræ │var.│18│46│+ 33°│15′│Composite spectra with variable │
│ │ │ │ │ │ │ and shifting bright lines. │
│υ Sagitarii │ 4·7│19│16│− 16°│ 8′│Hβ variably bright (A. C. │
│ │ │ │ │ │ │ Maury). │
│ε Capricorni │ 4·5│21│36│− 19°│54′│Composite helium spectrum. │
│ │ │ │ │ │ │ Changes possibly explicable by│
│ │ │ │ │ │ │ motion-shifts of two │
│ │ │ │ │ │ │ dissimilar sets of dark lines │
│ │ │ │ │ │ │ (A. J. Cannon). │
└───────────────┴────┴──┴──┴─────┴───┴────────────────────────────────┘
TABLE II
LIST OF SPECTROSCOPIC BINARIES
┌─────────────┬───────┬─────────┬────────┬──────┬─────────────────────┐
│Name of Star.│ R. A. │ Dec. │ Mag. │Period│ Remarks. │
│ │ 1900. │ 1900. │ │ in │ │
│ │ │ │ │Days. │ │
├─────────────┼───────┼─────────┼────────┼──────┼─────────────────────┤
│ │h. m.│ │ │ │ │
│η Andromedæ │ 0 52│+ 22° 52′│ 4·6│ │Variable radial │
│ │ │ │ │ │ motion discovered │
│ │ │ │ │ │ by Campbell, 1900. │
│ │ │ │ │ │ Spectrum of │
│ │ │ │ │ │ companion faintly │
│ │ │ │ │ │ visible. Solar │
│ │ │ │ │ │ type. │
│Polaris │ 1 22│+ 88° 46′│ 2·1│ 3·97│Variable velocity │
│ │ │ │ │ │ detected by │
│ │ │ │ │ │ Campbell, 1899. │
│ │ │ │ │ │ Spectrum early │
│ │ │ │ │ │ solar. Companion │
│ │ │ │ │ │ dark. Further │
│ │ │ │ │ │ disturbance │
│ │ │ │ │ │ indicated. │
│φ Persei │ 1 37·4│+ 50° 11′│ 4·2│ │Variable velocity │
│ │ │ │ │ │ detected by │
│ │ │ │ │ │ Campbell in 1902. │
│ │ │ │ │ │ Bright-line helium │
│ │ │ │ │ │ spectrum. │
│ξ Piscium │ 1 48│+ 2° 42′│ 4·7│ │Variable velocity │
│ │ │ │ │ │ discovered by │
│ │ │ │ │ │ Campbell, 1900. │
│ │ │ │ │ │ Companion sensibly │
│ │ │ │ │ │ dark. │
│ξ_{1} Ceti │ 2 8│+ 8° 23′│ 4·4│ │Variable velocity │
│ │ │ │ │ │ discovered by │
│ │ │ │ │ │ Campbell, October │
│ │ │ │ │ │ 1900. Companion │
│ │ │ │ │ │ dark. │
│12 Persei │ 2 36│+ 39° 46′│ 4·9│ │Discovered by │
│ │ │ │ │ │ Campbell, January │
│ │ │ │ │ │ 1900. Two similar │
│ │ │ │ │ │ spectra visible at │
│ │ │ │ │ │ elongations. │
│τ Persei │ 2 47│+ 52° 22′│ 4·0│ │Radial velocity found│
│ │ │ │ │ │ variable by │
│ │ │ │ │ │ Campbell in October│
│ │ │ │ │ │ 1900. Spectrum │
│ │ │ │ │ │ previously observed│
│ │ │ │ │ │ as composite by A. │
│ │ │ │ │ │ C. Maury. Solar │
│ │ │ │ │ │ type. │
│β Persei │ 3 2│+ 40° 34′│ var.│ 2·87│Alternations of │
│ (Algol) │ │ │ │ │ approach and │
│ │ │ │ │ │ recession │
│ │ │ │ │ │ discovered by │
│ │ │ │ │ │ Vogel, 1889. │
│ │ │ │ │ │ Companion obscure. │
│ο Persei │ 3 38│ +31° 58′│ 4·0│ │Found by W. S. Adams │
│ │ │ │ │ │ in 1902 to vary in │
│ │ │ │ │ │ radial velocity to │
│ │ │ │ │ │ the extent of 251 │
│ │ │ │ │ │ kil. Single │
│ │ │ │ │ │ spectrum of helium │
│ │ │ │ │ │ type. │
│λ Tauri │ 3 55│ +12° 12′│ var.│ 3·95│Changes of velocity │
│ │ │ │ │ │ measured by │
│ │ │ │ │ │ Bélopolsky, 1897. │
│ │ │ │ │ │ Spectrum │
│ │ │ │ │ │ periodically │
│ │ │ │ │ │ double. Helium │
│ │ │ │ │ │ type. │
│α Aurigæ │ 5 9│ +45° 54′│ 0·2│ 104│Discovered by │
│ (Capella) │ │ │ │ │ Campbell and │
│ │ │ │ │ │ Newall, 1899. │
│ │ │ │ │ │ Spectrum composite.│
│η Orionis │ 5 19·4│ −2° 29′│ 3·5│ │Variable velocity │
│ │ │ │ │ │ detected with the │
│ │ │ │ │ │ Bruce spectrograph │
│ │ │ │ │ │ in 1901 by W. S. │
│ │ │ │ │ │ Adams and E. B. │
│ │ │ │ │ │ Frost. │
│δ Orionis │ 5 27│ −0° 22′│ 2·4│ 1·92│Discovered by │
│ │ │ │ │ │ Deslandres, 1900. │
│ │ │ │ │ │ Spectrum of helium │
│ │ │ │ │ │ type. Companion │
│ │ │ │ │ │ obscure. │
│β Aurigæ │ 5 52│ +44° 56′│ 2·1│ 3·98│Discovered by Miss │
│ │ │ │ │ │ Maury in 1889. │
│ │ │ │ │ │ Spectrum first │
│ │ │ │ │ │ type; doubled │
│ │ │ │ │ │ periodically. │
│η Geminorum │ 6 8·8│ +22° 33′│ 3·2–4·2│ │Variable velocity │
│ │ │ │(period,│ │ detected by │
│ │ │ │ 231^d)│ │ Campbell in 1902. │
│ │ │ │ │ │ Close visual │
│ │ │ │ │ │ companion │
│ │ │ │ │ │ discovered by │
│ │ │ │ │ │ Burnham, 1881. Slow│
│ │ │ │ │ │ revolution │
│ │ │ │ │ │ indicated. The │
│ │ │ │ │ │ variable shows a │
│ │ │ │ │ │ fluted spectrum. │
│ζ Geminorum │ 6 58│ +20° 43′│ var.│ 10·15│Discovered by │
│ │ │ │ │ │ Bélopolsky, 1898. │
│ │ │ │ │ │ Subordinate period │
│ │ │ │ │ │ of 3·38^d detected │
│ │ │ │ │ │ by Campbell. │
│ │ │ │ │ │ Spectrum solar │
│ │ │ │ │ │ type. Companion │
│ │ │ │ │ │ dark. │
│γ Canis │ 7 23│ +9° 8′│ 4·6│ │Discovered by │
│ Minoris │ │ │ │ │ Campbell in 1902 to│
│ │ │ │ │ │ vary in velocity to│
│ │ │ │ │ │ the extent of 8 │
│ │ │ │ │ │ miles per second. │
│α′ Geminorum │ 7 28│ +32° 7′│ 2·0│ 2·95│Discovered by │
│ (Castor) │ │ │ │ │ Bélopolsky, 1896. │
│ │ │ │ │ │ First type │
│ │ │ │ │ │ spectrum. Companion│
│ │ │ │ │ │ obscure. Line of │
│ │ │ │ │ │ apsides found to │
│ │ │ │ │ │ revolve in 2100^d. │
│V Puppis │ 7 55│ −48° 58′│ var.│ 1·45│Periodical doubling │
│ │ │ │ │ │ of lines detected │
│ │ │ │ │ │ by Pickering from │
│ │ │ │ │ │ Arequipa plates in │
│ │ │ │ │ │ 1896. A. W. Roberts│
│ │ │ │ │ │ finds components to│
│ │ │ │ │ │ revolve in contact.│
│ │ │ │ │ │ Helium spectrum. │
│ε Hydræ │ 8 42│ +6° 48′│ 3·6│ │Variable velocity │
│ │ │ │ │ │ detected by │
│ │ │ │ │ │ Campbell, December │
│ │ │ │ │ │ 1900. Solar │
│ │ │ │ │ │ spectrum. │
│ο Leonis │ 9 36│ +10° 21′│ 3·8│ 14·5│Discovered by │
│ │ │ │ │ │ Campbell, 1898. │
│ │ │ │ │ │ Spectrum previously│
│ │ │ │ │ │ noticed by Miss │
│ │ │ │ │ │ Maury to be │
│ │ │ │ │ │ compounded of two │
│ │ │ │ │ │ varieties of the │
│ │ │ │ │ │ Sirian type. │
│ξ Ursæ │11 13│ +32° 6′│ 3·8│ │Principal component │
│ Majoris │ │ │ │ │ of visual binary │
│ │ │ │ │ │ found by Wright in │
│ │ │ │ │ │ 1900 to be │
│ │ │ │ │ │ spectroscopically │
│ │ │ │ │ │ double. Spectrum │
│ │ │ │ │ │ solar. │
│93 Leonis │11 43│ +20° 46′│ 4·6│ │Variable velocity │
│ │ │ │ │ │ detected by │
│ │ │ │ │ │ Campbell, 1900. │
│ξ Ursæ │13 20│ +55° 27′│ 2·4│ 20·6│Discovered by │
│ Majoris │ │ │ │ │ Pickering, 1889. │
│ │ │ │ │ │ Period fixed by │
│ │ │ │ │ │ Vogel, 1901. │
│ │ │ │ │ │ Spectrum advanced │
│ │ │ │ │ │ helium type. │
│ │ │ │ │ │ Components equally │
│ │ │ │ │ │ bright. │
│α Virginis │13 20│ −10° 38′│ 1·2│ 4·0│Discovered by Vogel, │
│ │ │ │ │ │ 1890. Companion │
│ │ │ │ │ │ faintly luminous. │
│ │ │ │ │ │ Helium spectrum. │
│ζ Centuari │13 49│ −46° 47′│ 2·8│ 8·02│Discovered by Mrs. │
│ │ │ │ │ │ Fleming, 1899. │
│ │ │ │ │ │ Components │
│ │ │ │ │ │ unequally bright. │
│ │ │ │ │ │ Spectrum helium │
│ │ │ │ │ │ type. │
│d Boötis │14 6│ +25° 34′│ 4·8│ │Variable velocity │
│ │ │ │ │ │ discovered by │
│ │ │ │ │ │ Wright, April 1900.│
│β Lupi │14 52│ −42° 44′│ 2·7│ │Discovered by Mrs. │
│ │ │ │ │ │ Fleming, 1897. │
│ │ │ │ │ │ Components equally │
│ │ │ │ │ │ luminous. Helium │
│ │ │ │ │ │ spectrum. │
│δ Libræ │14 56│ −8° 8′│ var.│ 2·33│Variable velocity │
│ │ │ │ │ │ detected by Adams, │
│ │ │ │ │ │ 1902. Spectrum │
│ │ │ │ │ │ advanced helium │
│ │ │ │ │ │ type. │
│ε Libræ │15 19│ −9° 57′│ 5·2│ 90+│Discovered by │
│ │ │ │ │ │ Campbell, 1899. │
│ │ │ │ │ │ Solar spectrum. │
│ │ │ │ │ │ Companion obscure. │
│π Scorpii │15 53│ −25° 49′│ 3·1│ 1·57│Discovered by Miss │
│ │ │ │ │ │ Cannon, 1899. │
│ │ │ │ │ │ Helium spectrum. │
│ │ │ │ │ │ Components │
│ │ │ │ │ │ unequally bright. │
│Θ Draconis │16 0│ +58° 50′│ 4·2│ 9│Discovered by │
│ │ │ │ │ │ Campbell, 1899. │
│ │ │ │ │ │ Spectrum solar │
│ │ │ │ │ │ type. Companion │
│ │ │ │ │ │ obscure. │
│β Herculis │16 26│ +21° 42′│ 2·8│ │Variable velocity │
│ │ │ │ │ │ detected by │
│ │ │ │ │ │ Campbell, 1899. │
│ │ │ │ │ │ Companion dark. │
│ │ │ │ │ │ Arcturian spectrum.│
│μ_{1} Scorpii│16 45│ −37° 53′│ 3·3│ 1·45│Discovered by Bailey,│
│ │ │ │ │ │ 1896. Components │
│ │ │ │ │ │ unequally bright, │
│ │ │ │ │ │ perhaps variable. │
│ │ │ │ │ │ Spectra of helium │
│ │ │ │ │ │ type. │
│_h_ Draconis │16 55│ +65° 17′│ 4·7│ │Variable velocity │
│ │ │ │ │ │ detected by │
│ │ │ │ │ │ Campbell, 1899. │
│ │ │ │ │ │ Early solar │
│ │ │ │ │ │ spectrum. Companion│
│ │ │ │ │ │ dark. │
│ε Ursæ │16 56│ +82° 12′│ 4·5│ │Discovered by │
│ Minoris │ │ │ │ │ Campbell, 1899. │
│ │ │ │ │ │ Spectrum solar. │
│ │ │ │ │ │ Companion obscure. │
│ω Draconis │17 38│ +68° 48′│ 4·9│ │Discovered by │
│ │ │ │ │ │ Campbell, 1899. │
│ │ │ │ │ │ Spectrum solar. │
│ │ │ │ │ │ Companion obscure. │
│χ Draconis │18 23│ +72° 42′│ 3·7│ 282│Variable velocity │
│ │ │ │ │ │ detected by │
│ │ │ │ │ │ Campbell, 1898. │
│ │ │ │ │ │ Period computed by │
│ │ │ │ │ │ Wright. Early solar│
│ │ │ │ │ │ spectrum. Companion│
│ │ │ │ │ │ dark. │
│2 Scuti │18 37│ −9° 9′│ 4·8│ │Variable velocity │
│ │ │ │ │ │ detected by Wright,│
│ │ │ │ │ │ 1900. Companion │
│ │ │ │ │ │ dark. │
│β Scuti │18 42│ −4° 51′│ 4·4│ │Variable velocity │
│ │ │ │ │ │ detected by Wright,│
│ │ │ │ │ │ 1900. Companion │
│ │ │ │ │ │ obscure. │
│β Lyræ │18 46│ +33° 15′│ var.│ 12·91│Binary character │
│ │ │ │ │ │ discovered by │
│ │ │ │ │ │ Pickering, 1891. │
│ │ │ │ │ │ Bright-line helium │
│ │ │ │ │ │ spectrum. │
│ │ │ │ │ │ Components │
│ │ │ │ │ │ luminous. │
│113 Herculis │18 50│ +22° 32′│ 4·6│ │Variable velocity │
│ │ │ │ │ │ detected by Wright,│
│ │ │ │ │ │ July 1900. │
│ │ │ │ │ │ Companion obscure. │
│υ Sagittarii │19 16│ −16° 8′│ 4·7│ │Variable velocity │
│ │ │ │ │ │ discovered by │
│ │ │ │ │ │ Campbell, 1899. │
│ │ │ │ │ │ Spectrum noted as │
│ │ │ │ │ │ composite by Miss │
│ │ │ │ │ │ Maury. Of helium │
│ │ │ │ │ │ type with bright │
│ │ │ │ │ │ lines. │
│η Aquilæ │19 47│ +0° 45′│ var.│ 7·18│Variable velocity │
│ │ │ │ │ │ detected by │
│ │ │ │ │ │ Bélopolsky, 1895. │
│ │ │ │ │ │ Spectrum solar. │
│ │ │ │ │ │ Companion dark. │
│ο_{1} Cygni │20 10│ +46° 26′│ 3·8│ │Variable velocity │
│ │ │ │ │ │ detected by │
│ │ │ │ │ │ Campbell, July │
│ │ │ │ │ │ 1900. Spectrum │
│ │ │ │ │ │ previously │
│ │ │ │ │ │ described by Miss │
│ │ │ │ │ │ Maury as including │
│ │ │ │ │ │ Sirian and solar │
│ │ │ │ │ │ ingredients. │
│β Capricorni │20 15│ −15° 5′│ 3·4│ │Variable velocity │
│ │ │ │ │ │ detected by │
│ │ │ │ │ │ Campbell, 1899. │
│ │ │ │ │ │ Spectrum previously│
│ │ │ │ │ │ perceived by Miss │
│ │ │ │ │ │ Maury to be of │
│ │ │ │ │ │ Sirian and solar │
│ │ │ │ │ │ composition. │
│α Equulei │21 11│ +4° 50′│ 4·1│ │Variable velocity to │
│ │ │ │ │ │ the extent of 15 │
│ │ │ │ │ │ miles a second │
│ │ │ │ │ │ discovered by │
│ │ │ │ │ │ Campbell in 1902. │
│ │ │ │ │ │ Miss Maury had │
│ │ │ │ │ │ recorded a │
│ │ │ │ │ │ composite spectrum,│
│ │ │ │ │ │ solar and Sirian. │
│κ Pegasi │21 40│ +25° 11′│ 4·2│ 6±│Smaller member of the│
│ │ │ │ │ │ visual binary found│
│ │ │ │ │ │ by Campbell in 1900│
│ │ │ │ │ │ to be in rapid │
│ │ │ │ │ │ revolution round a │
│ │ │ │ │ │ dark companion. │
│ │ │ │ │ │ Sirian spectrum. │
│ι Pegasi │22 2│ +24° 51′│ 4·0│ │Variable velocity │
│ │ │ │ │ │ detected by │
│ │ │ │ │ │ Campbell, 1898. │
│ │ │ │ │ │ Spectrum of Procyon│
│ │ │ │ │ │ class. Companion │
│ │ │ │ │ │ obscure. │
│δ Cephei │22 25│ +57° 54′│ var.│ 5·37│Binary character │
│ │ │ │ │ │ discovered by │
│ │ │ │ │ │ Bélopolsky, 1894. │
│ │ │ │ │ │ Solar spectrum. │
│ │ │ │ │ │ Companion dark. │
│η Pegasi │22 38│ +29° 42′│ 3·1│ 818·0│Variable velocity │
│ │ │ │ │ │ detected by │
│ │ │ │ │ │ Campbell, 1898. │
│ │ │ │ │ │ Spectrum solar. │
│ │ │ │ │ │ Companion dark. │
│ο Andromedæ │22 57│ +41° 47′│ 3·8│ │Variable velocity │
│ │ │ │ │ │ detected by │
│ │ │ │ │ │ Campbell, 1902. │
│ │ │ │ │ │ Composite │
│ │ │ │ │ │ spectrum—Sirian and│
│ │ │ │ │ │ Orion—recorded by │
│ │ │ │ │ │ Miss Maury. │
│π Cephei │23 5│ +74° 1′│ 4·5│ │Variable motion │
│ │ │ 5 │ │ │ detected by │
│ │ │ │ │ │ Campbell, 1900. │
│ │ │ │ │ │ Companion dark. │
│λ Andromedæ │23 33│ +45° 56′│ 4·0│ 19·2│Variable motion │
│ │ │ │ │ │ detected by │
│ │ │ │ │ │ Campbell, 1899. │
│ │ │ │ │ │ Spectrum Arcturian.│
│ │ │ │ │ │ Companion dark. │
└─────────────┴───────┴─────────┴────────┴──────┴─────────────────────┘
INDEX
Abbe, structures in solar corona, 129
Abbot, measurements of coronal heat, 131, 138
Abney, Sir William, photography of infra-red solar spectrum, 25;
theoretical effects of rotation in stellar spectra, 280
Airy, the solar sierra, 102
Alcyone, a helium star, 194;
red hydrogen line bright in spectrum, 229, 230, 279, 284;
coupled with a dark line, 420;
radiative power, 415;
attendant nebulosities, 418
Aldebaran, spectral character, 183, 207;
parallax and luminosity, 208;
a perspective member of the Hyades, 412
Alexander, contour of Owl nebula, 473;
bi-annular nebula, 490
Algol, density, 192, 303;
spectrum, 194, 197, 283;
supposed colour-change, 256;
probable velocity of rotation, 283;
eclipses, 302;
system, 303–306;
dark satellite, 302, 401
Al-Sûfi, redness of Algol, 256;
magnitude of Θ Eridani, 373
Altair, peculiar spectrum, 280;
rotational hypothesis, 281;
inapplicability, 282, 283;
incipient bright lines, 284
Ambronn, triangulation of the Pleiades, 421
Ames, spectral researches, 34, 53
Anderson, variability of T Andromedæ, 358;
fading of Θ Eridani, 373;
discoveries of Nova Aurigæ, 375;
and of Nova Persei, 388
Andromeda nebula, temporary star in, 385;
spectrum, 439, 449;
spirality, 440;
attendants, 441, 457;
constitution, 450
Ångström, C. J., recognition of hydrogen-absorption in the sun, 52
Ångström, K., bands of telluric absorption traced to carbon dioxide,
24;
atmospheric heat-stoppage, 65
Annular nebulæ, relation to planetaries, 469, 472;
examples, 484–493;
nuclear stars, 486, 489, 490, 493;
spectra, 488, 491;
structures of intermediate character, 490, 493;
desirability of further research, 494
Antares, shows a typical fluted spectrum, 179, 184, 210, 211;
adjacent nebula, 190, 514;
actual brightness, 213, 214
Antarian stars, 179, 184, 209–214;
development, 272, 276, 277, 278;
probable massiveness, 275
Antoniadi, nucleus of ring-nebula in Cygnus, 489
Aquilæ, η, light-change, 321;
orbit, 322, 323
Archenhold, photograph of a nebula in Perseus, 513
Arcturus, spectrum, 182, 183, 205, 207;
luminous power, 205
Argelander, period of ζ Geminorum, 328;
light-curve of β Lyræ, 337;
inequalities of Mira, 348, 349;
of χ Cygni, 352;
period of R Lyræ, 368;
disappearances of R Coronæ, 371
Argon, non-apparent in the sun, 28, 30
Argûs, γ, bright-line spectrum, 187, 238, 239
Astrophysics, prevision of, 1;
development, 2–5;
widening of scope, 5–8;
character and future, 9, 10
Atlas, a suspected binary star, 421
Aurigæ, β, a spectroscopic binary, 291
Auroræ, analogy with solar corona, 139;
abnormal scarcity, 156
Auwers, detection of a nebulous star, 471;
observation of Hind’s variable nebula, 523
Bacon, prevision of astrophysics, 1, 2
Bacon, Miss, coronal photographs, 135
Bailey, double spectrum of μ Scorpii, 292;
of V Puppis, 334;
discovery of cluster-variables, 336, 434;
their mode of light-change, 435, 437;
spectrograph of Nova Normæ, 382;
counts of the Pleiades, 416;
encircling nebulosity, 419;
photograph of ω Centauri, 431
Baillaud and Bourget, photograph of a nondescript nebula, 519
Ball, Sir Robert, parallax of 1618 Groombridge, 206
Balmer, law of series, 52–54
Barnard, photographic investigation of the Milky Way, 7, 539, 540, 544;
observations of cluster-variables, 177, 434, 435;
photographs of a nebula in Monoceros, 190, 425, 426;
of galactic nebulosities, 205, 513, 514;
of Messier 11, 411;
of nebulosities encircling the Pleiades, 418, 420;
of Messier 8, 424;
of fan nebulæ, 447;
of a nebular group, 458;
of nebulous stars, 462, 463, 464, 465, 466;
of nebulous formation in Orion, 497;
detection of stars in trapezium, 230, 495;
observation of Τ Tauri, 372, 373;
nebulous and non-nebulous clusters, 412;
visual discoveries of nebulæ, 417, 474, 487;
portrait-lens photography, 423;
globular clusters non-nebulous, 433;
Stephan’s star non-nebulous, 467;
central star in Lyra nebula, 487;
structure of an annular nebula, 493;
notices of variable nebulæ, 523, 524, 525, 526, 527;
composition of the Milky Way, 542
Baxendell, eclipses of λ Tauri, 307;
minima of S Ursæ Majoris, 353;
periodicity of R Lyræ, 368
Bayer, star-maps of 1603, 371
Becker, telluric spectrum, 23
Bell, nebulous formation round Nova Persei, 395
Bellatrix, a typical helium star, 191
Bélopolsky, solar eclipse of 1896, 128;
correspondence of coronal changes with surface-phenomena, 129;
rotation of faculæ, 145;
of the corona, 147;
nitrogen lines in P Cygni, 235;
system of Castor, 293, 294;
radial motion of λ Tauri, 307;
of δ Cephei, 320;
of ζ Geminorum, 328;
system of β Lyræ, 339, 340
Berberich, effects on Encke’s comet of solar periodicity, 158
Bessel, dark stars, 400
Betelgeux, spectral affinities, 183, 210, 211;
real magnitude, 213, 214;
irregular variability, 369
Bevis, discovery of Crab nebula, 517
Bigelow, magnetic theory of corona, 138, 139;
solar rotation, 143;
modes of propagation of solar energy, 157
Bigourdan, observation of a variable nebula, 526
Birmingham, colours of stars, 257, 258
Boguslawski, record of a variable nebula, 528
Boisbaudrin, discovery of gallium, 28
Bolometer, applied to investigate infra-red solar spectrum, 22;
to measure coronal heat, 131
Boltzmann, law of radiation, 64
Bond, measurement of stars in Orion nebula, 504
Bouguer, darkening of the sun’s disc, 70
Boys, invention of radio-micrometer, 64
Bradley, measures of β Cygni, 264;
of Castor, 293
Brown, Miss, drawing of a spot-group, 79
Burckhalter, graduated coronal photographs, 133
Burnham, division of σ Orionis, 261;
of η Geminorum, 267;
observations of T Tauri, 372;
of Barnard’s Merope nebula, 417;
of double and triple nebulæ, 453, 458;
of nebulous stars, 461, 463, 464, 466, 467;
of planetary nebulæ, 474, 475, 480, 483;
of stellar nebulæ, 481;
of nuclear stars in annular nebulæ, 487, 489, 490;
of variable nebulæ, 523, 526, 528
Burns, magnitudes of galactic stars, 542
Buss, helium absorption in sun-spot spectra, 94
Calcium, isolation of its violet ray for solar photography, 18, 99,
101;
a constituent of the sun, 27;
emission lines in sun-spots, 95;
in faculæ, 100, 101;
in prominences, 110, 114, 115, 120;
in stars, 232;
absence from corona, 136;
absorption by in stellar spectra, 182, 185, 191, 192, 193, 200, 201,
203, 207, 209, 212, 225, 226, 390
Calvert, drawing of the Pleiades nebulosities, 419
Campbell, coronal spectrographs, 131, 132, 136;
bright and dark spectral series, 175, 229, 230, 238, 420;
spectra of bright-line helium stars, 186, 233, 420;
of Wolf-Rayet stars, 237, 239, 242;
spectrum of Rigel, 191;
of Mira, 223–225;
of γ Argûs, 238;
bright lines in fourth-type spectra, 218;
star with a hydrogen envelope, 240, 244;
detection of spectroscopic binaries, 266, 296–298;
orbit of ζ Geminorum, 328–330;
constitution of Nova Aurigæ, 378;
its spectrum, 380, 381;
spectrum of Nova Normæ, 383;
of Nova Centauri, 384;
of Nova Sagittarii, 385;
of Nova Aquilæ, 386;
of planetary nebulæ, 479, 480, 491;
of Orion nebula, 500, 501;
of Trifid nebula, 503;
relative brightness of nebular lines, 476;
description of a bi-annular nebula, 491
Cannon, Miss, bright-line stars, 186, 235, 239;
variable stellar spectra, 250;
spectrum of η Carinæ, 370, _note_
Canopus, nature of spectrum, 182;
remoteness, 204
Cantor, electrically illuminated gases non-absorptive, 140
Capella, spectral relationships, 183, 205;
duplicity, 294–296, 297
Carbon, a solar constituent, 29, 31, 219;
spectral effacement in presence of iron, 34;
condensed in photospheric clouds, 63;
present in the chromosphere, 118;
in stars, 180, 184, 216, 219, 278;
no trace of in Wolf-Rayet spectrum, 242;
bright in R Geminorum, 246
Carbon stars, spectrographed, 177;
nature of spectra, 179, 184, 185, 215–220;
bright lines in, 185, 216–219, 408;
white specimens, 220, 258;
distribution, 221;
affinities, 238;
development, 277, 278;
luminous instability, 358–360
Carinæ, η, nature of spectrum, 235, 370;
light-changes, 370, 371, 406;
position in Key-hole nebula, 507
Carlyle, colour of Sirius, 256
Carrington, movements of sun-spots, 84;
law of the sun’s rotation, 143, 146, 149;
cyclical shiftings of spot-zones, 151
Cassiopeiæ, γ, bright-line spectrum, 186, 233, 234, 279;
spectral fluctuations, 248, 249
Castor, spectrum, 203;
a triple system, 293, 294;
dark companion, 293, 401
Centauri, α_{2}, spectrograph of, 182;
a model sun, 192, 199, 205, 269
Centauri, ω, variable stars in, 333, 436;
telescopic aspect, 429;
central crowding of components, 430
Cephei, δ, a typical short-period variable, 319;
orbital movements, 320, 321, 323;
analogous objects enumerated, 324–326;
their distinctive qualities, 327
Ceraski, discovery of U Cephei, 309
Ceraski, Madame, discoveries of variable stars, 316
Cerium, a solar element, 27, 30;
base of a rare earth, 33
Chacornac, supposed observation of a temporary nebula, 522, 523
Chamberlin, theory of spiral nebulæ, 445
Chandler, movements of the earth’s axis, 159;
disturbances of Algol, 304–306;
phases of eclipsing stars, 311, 314;
discovery of a Geminid variable, 326;
distinctive character of the class, 328;
variations of U Pegasi, 332;
cycle of Mira, 348;
of R Leonis, 356;
redness and periods of variable stars, 358
Chase, parallax of Algol, 306
Chemistry, scope of celestial, 6;
solar, 18, 21, 25–34;
of sun-spots, 91, 163;
of helium stars, 189;
of hydrogen stars, 197;
of Antarian stars, 210;
of carbon stars, 220;
of Mira variables, 226;
of Wolf-Rayet stars, 241
Chevremont, variable stars in the Pleiades, 421
Chromosphere, composition and depth, 16, 102, 109;
deficiency of absorptive power, 47, 161;
spectrum, 112–114, 116, 118, 119, 163
Clark, Alvan G., black markings in prominences, 110;
detection of additional trapezium stars, 230, 495
Cleve, rare metals, 33;
analysis of clevite, 57
Clevite, helium occluded by, 56
Colour variability, elusive of observation, 253;
relation to light-change, 254, 255;
incidental occurrence, 255–258;
in double stars, 259–262
Comets, mimicked by coronal rays, 127;
variation of conspicuousness with the solar condition, 158
Common, photograph of a globular cluster, 433;
variability of components, 434;
photograph of a cometary nebula, 446;
a triple group of nebulæ, 454
Comte, illusory forecast, 1
Copeland, helium-line in spectrum of Orion nebula, 174, 499;
colours of stars, 256, 257;
spectrum of U Orionis, 350;
of U Geminorum, 366;
spectroscopic detection of nebulæ, 480, 482
Cornu, telluric absorption, 22;
spectral series, 53
Corona, problem presented by, 9, 140;
tenuity, 16;
periodical variations, 20, 127–129;
structure, 123–127;
chromospheric relations, 129;
spectrum, 130, 131;
polarisation, 132;
photography, 132–136, 141;
dark markings in, 134;
rotation, 136, 141;
theories regarding, 137–140
Coronium, importance of in solar physics, 52;
subtlety, 60;
probable qualities, 61;
spectrum, 130;
non-absorptive, 140;
an unknown element, 141, 163
Cortie, structure of sun-spots, 76, 77, 80;
their alternations in activity, 85;
average duration, 86;
their spectra, 90, 91;
rotation of faculæ, 146;
spectral anomalies of Nova Persei, 392
Crab nebula, discovery, 517;
spectrum, 518
Crookes, Sir William, meta-elements, 33, 34
Crucis, β, a typical oxygen star, 190, 193
Cygni, β, colours and spectra, 264, 265
Cygni, χ, bright-line spectrum, 226, 227;
colour-changes, 255
Cygni, P, nature of spectrum, 186, 233, 234, 235;
irregular variability, 406
Cysatus, first notice of Orion nebula, 495
Dark stars, problem they present, 176, 177, 189;
probable origin, 276, 277;
coupled with bright stars, 289, 292, 293, 298, 317, 400, 401, 403;
two classes, 403;
galactic relations, 543
Darquier, discovery of annular nebula, 484
D’Arrest, drawing of a nebula, 443;
observations of nebulous stars, 454, 461, 465;
sharpness of 55 Andromedæ, 466;
stellar satellites to nebulæ, 483;
annular nebula, 493;
nondescript nebula, 520;
variable nebulæ, 523, 525, 526
Davidson, black markings in prominences, 110
Dawes, black openings in sun-spots, 75;
colour of δ Cygni, 261
De la Rue, stereoscopic view of a sun-spot, 81
Dembowski, colours of double stars, 260, 261
Deneb (α Cygni), spectral relationships, 193, 197
Denning, observations of a variable nebula, 528
Deslandres, photography of prominences, 9, 18, 98, 103;
selective photography of the sun, 49, 99;
facular flames, 100;
electrical origin of chromospheric luminosity, 115;
ultra-violet prominence spectrum, 119;
the sun as a bright-line star, 121;
coronal spectrograms, 132;
experiments on coronal rotation, 136, 137;
coronal heat, 141;
spectrum of Altair, 281, 284
Dewar, researches at low temperatures, 60
Dissociation, in sun-spots, 90, 96, 163;
of calcium, 114
Doberck, colour of Hind’s star, 257;
of γ Delphini, 260
Doppler’s principle, 4, 19, 106, 297, 390
Double stars, evolution, 176;
variable tints, 259–262;
spectra, 263–270, 275, 276;
indistinguishable from spectroscopic binaries, 297
Draco planetary, helical conformation, 474;
spectrum, 475
Draper Catalogue, 173
Draper, Henry, illusory bright oxygen-lines in solar spectrum, 28
Draper, J. W., illusory dark oxygen-lines in solar spectrum, 28
Dreyer, observation of a double nebula, 454;
non-nebulosity of 55 Andromedæ, 466;
alleged displacement of Omega nebula, 512;
observations of variable nebulæ, 528
Dumb-Bell nebula, analogous objects, 481, 517;
structure, 516;
spectrum, 517
Dunér, spectroscopic measures of the sun’s rotation, 19, 144, 145, 146,
147, 283;
spectra of sun-spots, 89, 90;
spectra of fourth-type stars, 216, 218, 219, 220;
colours of 95 Herculis, 260;
revolutions of Y Cygni, 311, 312;
minima of Z Herculis, 314
Dunlop, a blue cluster, 414
Dyson and Lewis, elongation of Capella, 295
East, refraction in sun-spots, 80
Eberhard, spectrum of χ Cygni, 226
Ebert, temperature of the sun, 66;
theory of the corona, 139, 140
Eclipses, solar, observations during, 9, 19, 20;
disclosure by of reversing layer, 44–46;
of prominences, 109, 120;
of coronal halo, 123, 125–128, 130, 162
Eclipses, stellar, 299–301, 317
Eclipsing stars, mean density, 272, 303, 307, 310, 313, 314;
rotational speed, 282, 283;
enumerated and described, 299, 318;
light-curves, 309, 317;
spectra, 316;
absent from clusters, 438
Eddie, light-change of δ Cephei, 321
Eisig, spectrum of oxygen, 28
Electricity, spectral influences imperfectly understood, 6;
undulatory, 22;
supposed effectiveness in chromospheric illumination, 115;
action of in corona, 137–140
Elkin, parallax of Capella, 295;
measurements of the Pleiades, 415
Ellerman, spectrographs of carbon stars, 185, 216;
of a Wolf-Rayet star, 239
Ellis, solar and magnetic periodicity, 154
Engelmann, colour of δ Cygni, 261
Espin, spectrum of α Herculis drawn by, 183;
catalogue of fourth-type stars, 215;
spectrum of φ Persei, 235;
of R Coronæ, 247;
colours of stars, 255, 256, 257;
light-change of R Cygni, 357;
suggested period of 63 Cygni, 369;
red stars in Perseus cluster, 412
Evershed, photographs of flash spectrum, 46;
constitution of reversing layer, 47, 48;
light from spot-umbræ, 75;
their spectra, 93;
prominence-spectrum, 112, 116, 119;
titanium in the chromosphere, 118
Fabricius, variability of Mira, 348, 349
Faculæ, connection with spots, 74, 101, 151, 153, 161;
status and distribution, 98, 100;
photographed, 99, 100;
rotation, 145–147
Faye, the sun’s rotation, 149
Fenet, map of stars in M 11, 410
Fényi, disturbance of reversing stratum, 50;
depth of chromosphere, 102;
observations of prominences, 103–108, 116
Finlay, parallax of Antares, 213;
magnitude of η Carinæ, 371
Fitzgerald, electrical relations of the solar corona, 140
Flammarion, colours of double stars, 260, 261
Flamsteed, nebulosity of 55 Andromedæ, 466, 467
Flanery, variations of R Scuti, 363, 364
Fleming, Mrs., discoveries and classification of variable stars, 186,
227;
detection of an eclipsing star, 316;
duplicity of β Lyræ, 338;
variability of W Puppis, 352;
of V Delphini, 356;
discovery of Nova Normæ, 382;
of Nova Centauri, 384;
of Nova Sagittarii, 395;
of a planetary nebula, 476;
spectrum of a star in Libra, 512
Fomalhaut, character of spectrum, 201, 202
Fowler, photographs of Indian eclipse, 130
Franks, colours of stars, 257, 260
Fraunhofer, survey of the solar spectrum, 21, 22
Fraunhofer-lines, their interpretation, 13, 17, 21, 26, 29, 34;
motion-displacements, 19, 42, 144;
unidentified residuum, 36;
variability, 37;
effects of pressure on, 38, 51;
structural complexities, 40, 41, 43, 243;
tranquillity of originating strata, 50, 154;
in sun-spots, 93, 146;
in faculæ, 98, 146;
in reflected coronal light, 132;
in spectrum of Andromeda nebula, 440
Frost, level of sun-spots, 79;
thermal power of umbræ, 81, 82;
refraction in the sun, 167
Gadolin, discovery of yttria, 33
Gale, discovery of an annular nebula, 489
Gallium, recognition in the sun, 28, 118;
in α Cygni, 193
Galton, description of solar corona, 123
Gautier, sun-spot and magnetic periods, 3
Geminorum, R, carbon-bands bright in spectrum, 246
Geminorum, U, diffuse aspect, 361;
light-changes, 365, 366
Geminorum, ζ, a typical short-period variable, 319, 328;
orbit, 329, 330;
members of its class, 331–335
Gill, Sir David, Cape Durchmusterung, 173;
spectrograph of α_{2} Centauri, 182, 269;
oxygen in stars, 191;
α_{2} Centauri a replica of the sun, 192, 199;
parallax of Sirius, 198;
of Fomalhaut, 202;
of Canopus, 204;
spectrum of η Carinæ, 235;
photograph of Argo nebula, 507, 508
Gilliss, redness of η Carinæ, 371
Goodricke, variability of β Lyræ, 337
Gore, discovery of U Orionis, 350
Gothard, bright lines in γ Cassiopeiæ, 248, 249;
spectral changes in β Lyræ, 338;
ultra-violet spectrum of Nova Aurigæ, 381;
of planetary nebulæ, 479, 482;
of annulus in Lyra, 488;
of dumb-bell nebula, 517;
photograph of nuclear star in Lyra nebula, 487
Gould, red stars, 258, 261;
variability of RS Sagittarii, 308;
of R Trianguli, 324;
of L_{2} Puppis, 352
Gravity, undiscriminating action, 2;
universality, 3;
maintenance of sun’s heat by, 14;
neutralisation of effects upon solar appendages, 16, 51, 60;
effectiveness in stars, 194, 201, 206, 207;
gain of power with condensation, 272;
influence on stellar temperatures, 274
Groombridge, magnitude of R Cephei, 369
Grosch, corona of 1867, 127
Grover, observations of variable stars, 254, 361
Gruss and Laska, spectrum of R Leonis, 227
Guthnick, long inequality of Mira, 348
Hagen, minimum of U Geminorum, 366;
periodicity of S Persei, 370
Hahn, nuclear star in Lyra annular nebula, 486
Hale, photography of prominences, 9, 18, 99, 110;
duplicity of D_{3}, 57;
carbon in the chromosphere, 118;
spectra of prominences, 118, 119, 121;
prominence-forms in daylight and during eclipses, 120;
magnetic relations of chromosphere, 157;
spectrographs of carbon stars, 177, 185, 216, 220;
bright lines in, 185, 217–219, 238;
spectrum of Nova Persei, 392
Hall, measurement of stars in Præsepe, 412;
invisibility of star in Lyra nebula, 486
Halley, aurora of 1716, 156;
magnitude of θ Eridani, 373
Halm, function of the sun’s smoke-envelope, 72;
effects of solar periodicity upon terrestrial movements, 158;
theory of temporary stars, 398
Hansky, dark markings on prominences, 111;
drawings of coronal types, 128;
coronal structure, 130, 140
Hartley, spectral series, 53;
gallium a chromospheric constituent, 118
Hartley and Ramage, detection of gallium-lines in solar spectrum, 28
Hartwig, minima of Z Herculis, 314;
light-change of S^2 Cygni, 367
Harzer, solar rotation, 148
Hasselberg, investigations of metallic spectra, 26;
vanadium in the sun, 32
Hastings, constitution of solar atmosphere, 71
Helium, a constituent of prominences, 19, 113, 119;
non-absorptive in the sun, 29, 56, 60, 93;
terrestrial discovery, 29, 56, 174;
spectrum, 57, 58, 113, 114;
properties, 59;
absorption in sun-spots, 94, 195;
a constituent of gaseous nebulæ, 174, 477, 478, 480, 499;
absorption in stars, 174, 181, 190, 191, 195, 225, 228;
emission in stars, 175, 186, 187, 226–228, 350;
in Nova Aurigæ, 376;
in Nova Persei, 393;
mixed bright and dark series, 229, 230, 238, 239;
in β Lyræ, 338;
yellow series represented in nebulæ, 536, 537
Helium stars, distinguished by Vogel, 174, 181;
characteristics and varieties, 189–195;
nebular relationships, 189, 190, 272, 277, 279, 462;
distribution, 196, 543;
pass into Sirian stars, 197, 272, 277;
with bright lines, 229–236, 248, 251;
mean density, 272
Helmert, catalogue of stars in M 11, 410;
their variability, 411
Helmholtz, gravitational hypothesis of solar sustentation, 14
Herschel, Alexander, spectral series, 53
Herschel, Caroline, discoveries of nebulæ, 441
Herschel, Sir John, nebulosity round ι Orionis, 190;
colours of stars, 258, 259, 412;
observations of clusters, 414, 425;
nebulosity of 15 Monocerotis, 426;
globular clusters catalogued, 428;
observations of nebulæ, 441, 443, 446, 447, 456, 458;
double nebulæ, 452, 453;
nebulous stars, 463, 464, 465, 466;
Owl nebula, 472;
bi-nuclear planetary, 480;
star satellites to planetaries, 483;
description of Lyra nebula, 484;
planetaries in clusters, 490;
brightness of a star in Orion nebula, 504;
stars in Argo nebula, 507;
drawing of Argo nebula, 508;
multiple star in Trifid nebula, 509, 510;
observation of Omega nebula, 511, dumb-bell nebula, 516;
its miniatures, 517;
observations of variable nebulæ, 526, 528
Herschel, Sir William, discovery of binary stars, 3;
division of 11 Monocerotis, 233;
colours of double stars, 259, 260;
observations of Mira, 348, 349;
nebulous stars, 460, 462, 463;
planetary nebulæ, 471, 481;
annular nebulæ, 484, 489, 493;
aspect of Trifid nebula, 509;
multiple star in, 509, 511;
variable nebulæ observed by, 526, 528;
dark hole in Scorpio, 541
Hevelius, magnitude of R Cephei, 369
Hind, red star, 256;
variations of S Cancri, 306;
of U Geminorum, 365;
detection of T Tauri, 372, 523;
of a temporary nebula, 523
Höffler, parallax of stars in Ursa Major, 290
Holden, polar rays of the corona, 139;
dark lanes in Hercules cluster, 432;
helical nebulæ, 474;
structure of annular nebulæ, 485, 490;
ansæ of Saturn nebula, 492;
suspected changes in Orion nebula, 503;
variability of a star within its compass, 504;
evidence of alteration in Omega nebula, 512;
duplicate nondescript nebulæ, 519
Hornstein, the sun’s rotation, 146
Howlett, conformation of sun-spots, 80, 81
Huggins, Sir William, foundation of spectrography, 3;
application of Doppler’s principle, 4;
daylight coronal photography, 20, 135;
atmospheric absorption, 22;
hydrogen spectrum, 52;
duplicity of D_{3}, 57;
electrical theory of corona, 138;
spectra of double stars, 166, 265, 266;
stellar classification, 180;
constitution of Nova Aurigæ, 378;
spectra of nebulæ, 443, 475, 512, 520;
nebulosity of 55 Andromedæ, 466;
temperature in nebulæ, 535
Huggins, Sir William and Lady, spectrum of calcium, 115;
nitrogen-absorption in stars, 175, 191;
spectrographs of Rigel, 181; of Vega, 182;
of Arcturus, 182;
of α Aquilæ, 282;
effect of gravity on stellar spectra, 201, 274, 276;
spectrographic investigation of trapezium stars, 231, 232;
Wolf-Rayet spectrum, 242;
spectra of double stars, 264, 270;
stellar temperatures, 273;
oxygen in β Lyræ, 338;
unknown ultra-violet nebular ray, 476, 503
Humphreys and Mohler, effects of pressure on spectra, 39
Hussey, observations of Capella, 295;
glimpse of Nova Centauri, 395
Huygens, variability of P Cygni, 234;
notice of Orion nebula, 495
Hyades, a non-nebulous cluster, 412
Hydrogen, ultra-violet spectrum, 3, 52;
a chromospheric constituent, 16, 19, 56, 112, 116, 117;
harmonic relations of spectral lines, 52, 53;
a second series observed in stars, 54, 175, 181, 187, 189, 195, 237,
239, 240, 465;
in nebulæ, 479;
escape from earth’s atmosphere, 55;
spectrum truncated in the sun, 56;
bright in sun-spots, 95;
in faculæ, 101;
absorptive effects in stars, 179, 181, 182, 191, 197, 203, 210;
bright in variables, 185, 222, 352;
in helium stars, 229–335;
in Wolf-Rayet stars, 237–241;
in β Lyræ, 338, 339, 340;
in Nova Aurigæ, 376;
in Nova Persei, 390;
in nebulæ, 476, 478, 488, 500–502, 536, 537;
triple structure of bright lines in Mira, 224, 225, 238
Hydrogen stars, spectral characteristics, 179, 182, 197–202;
development, 272;
temperature, 273
Ingall, structure of a ray nebula, 442;
of an annular nebula, 492
Innes, investigation of eclipsing stars, 316;
magnitude of η Carinæ, 371
Iron, absorption in solar spectrum, 30, 40, 41;
in spot spectra, 90, 92, 96;
in stellar spectra, 182, 184, 191, 210, 212, 220;
spectral prepotency, 34;
bright lines of, in Mira, 225;
in χ Cygni, 226
Janson, discovery of P Cygni, 234
Janssen, solar photographs, 17, 73, 76;
corona of 1871, 125;
Fraunhofer-lines in coronal spectrum, 132
Javelle, measures of a planetary nebula, 483
Jewell, variable Fraunhofer-line, 37;
effects of pressure on wave-length, 38;
structure of Fraunhofer-lines, 40, 41, 163;
titanium-lines in chromospheric spectrum, 118;
rotation of reversing layer, 147
Julius, solar phenomena explained by anomalous refraction, 147
Kant, nature of the creative process, 545
Kapteyn, stellar distribution and spectral diversity, 173, 543;
variability of R^2 Puppis, 316;
progressive illumination of nebulosity round Nova Persei, 395
Kayser, spectral series, 53
Kayser and Runge, metallic spectra, 26
Keeler, import of spectroscopy, 3;
calcium in the sun, 115;
helium-absorption in Rigel, 174;
radial velocities of nebulæ, 177, 470, 475, 483, 493, 499;
spectroscopic indication of high temperature, 181, 201;
bright lines in fourth-type spectra, 218;
spectrum of a Wolf-Rayet star, 239;
hydrogen-envelope of another specimen, 241;
spectrum of γ Cassiopeiæ, 249;
D-lines in β Lyræ, 344;
photographs of T Tauri, 373;
of nebulæ, 417, 443, 444, 487, 492, 493;
of cluster in Hercules, 432;
errors of draughtsmen, 447;
double nebulæ, 452;
rifted nebula, 456;
spectroscopic experiment on rotation of a nebula, 469;
drawings of planetaries, 470, 478, 479, 490;
description of Owl nebula, 473;
Webb’s planetary, 480;
spectrum of a stellar nebula, 481;
structure of Lyra nebula, 485;
central star, 487;
hydrogen spectrum in nebulæ, 499, 500;
screened photograph of Orion nebula, 501;
ultra-violet ray in spectrum, 503;
spectrum of Trifid nebula, 510;
multiple star in, 511;
photographs of Hind’s variable nebula, 524, 525
Kepler, laws enounced by, 1;
prescience of, 2;
letter to Herwart, 542
Key, structure of annular nebula, 493
Key-hole nebula, relations to of scattered stars, 507;
extinction of one of its parts, 508;
spectrum, 509
Kirch, discovery of a globular cluster, 433
Kirchhoff, interpretation of Fraunhofer-lines, 13
Kirchhoff’s law, disregarded by solar helium, 93;
by nebular gases, 462, 467
Klinkerfues, parallax of Mizar, 290
Knopf, optical rationale of reversing layer, 166
Knott, nebulous aspect of U Geminorum, 361
Koch, variability of R Leonis, 355
Köhl, fading of a red star, 374
Konkoly, spectrum of γ Cassiopeiæ, 249;
of U Orionis, 350
Krüger, spectrum of R Leonis, 227;
of R Scuti, 248;
colours of stars, 256–258
Lagoon nebula, involves a cluster, 424
Lalande, observation of S Ursæ Majoris, 353;
of Draco planetary, 474
Lamont, measurements of M 11, 410;
possible temporary star in, 411
Lane, cometary forms in solar corona, 126;
heating of gaseous globes through condensation, 272, 273, 276
Langley, bolometric survey of infra-red spectrum, 22, 24;
selective absorption in solar atmosphere, 64, 70;
heat stoppage in terrestrial atmosphere, 65;
relation of temperature to spectral energy-curve, 66;
heat of sun-spots, 82;
observations during solar eclipses, 123, 127;
multiple star in Trifid nebula, 511;
glow of white-hot iron, 532
Laplace, self-absorption of sunlight, 70;
dark stars, 400
Lassell, star in a double nebula, 454;
description of a planetary nebula, 481;
observations of annular nebulæ, 489, 490, 493;
of Trifid nebula, 509;
multiple star in, 511
Le Chatelier, temperature of the sun, 66
Le Gentil, companion to the Andromeda nebula, 441
Lehmann-Filhés, orbit of β Aurigæ, 291
Lewis, spectra of mixed vapours, 34
Liais, black-edged prominence, 110;
drawing of solar corona, 127
Lindemann, observations of V Cygni, 359, 361
Littrow, triple nebula, 454
Liveing and Dewar, spectrum of liquid oxygen, 23;
heat-relations of magnesium-lines, 49;
spectral series, 53;
spectra of rare atmospheric gases, 114, 120
Lockyer, Sir Norman, application of Doppler’s principle to the sun, 19;
detection in the sun of carbon and vanadium, 31, 32;
disappearance of a Fraunhofer-line, 37;
photographs of flash spectrum, 46;
periodical changes in spot spectra, 89;
solar dissociation, 90, 96, 114;
enhanced lines in chromospheric spectrum, 119;
corona of 1871, 125;
wave-length of green coronal ray, 130;
spectrum of Bellatrix, 191;
of α Cygni, 193;
of α Aquilæ, 281;
of S Sagittæ, 325;
temperature of electric spark, 273;
system of β Lyræ, 339, 340;
meteoric hypothesis, 451, 534
Lockyer, Dr., disturbances of η Aquilæ, 323
Lohse, O., investigation of cerium spectrum, 30;
photographic measures of cluster in Perseus, 411
Looped nebula, peculiar spectrum, 251, 512
Lord, spectrum of a prominence, 116
Luizet, phases of U Vulpeculæ, 324
Lunt, spectrum of ε Canis Majoris, 182;
silicon in stars, 182, 191, 193
Lyræ, β, variability in light, 337;
spectrum, 338;
changes in, 339, 343–345;
system, 338–342, 345;
analogues, 345, 346
Lyra, ring nebula in, 484–488
McClean, photograph of a telluric band, 23;
spectroscopic character of the Milky Way, 173, 196, 543;
oxygen in stars, 175, 232, 239;
stellar classification, 180, 197;
importance of helium stars, 181;
spectral quality of early stars, 189;
spectrograms of γ Cygni, 204;
of Antarian stars, 211;
of η Carinæ, 235;
system of β Lyræ, 339;
spectrum of ι Orionis, 465
Mädler, corona of 18th July 1860, 123;
satellite of Mizar, 291
Magellanic clouds, analogy to Milky Way, 187, 242, 544;
Wolf-Rayet stars contained in, 242;
nebulæ, 512, 517
Magnetism, terrestrial, periodicity coincident with that of sun-spots,
3, 154;
sympathetic response to solar agitations, 156–159
Maia, light-power, 415;
attached nebulosity, 417, 446, 522;
suspected slow light-change, 421;
spectrum, 532
Mason and Smith, observations of Trifid nebula, 509
Maunder, pressure in reversing layer, 49;
helium spectrum, 58;
structure of sun-spots, 83;
duplicated disturbances, 85;
white prominences, 110;
coronal extensions, 134;
coronal photographs, 135;
eruptive nature of prominences, 137;
movements of spot-zones, 152;
solar periodicity, 156, 157;
constitution of nebulæ, 534
Maunder, Mrs., coronal photographs, 134;
nature of prominences, 137
Maury, Miss, stellar classification, 180, 181, 182, 183, 185, 186, 189,
192, 194, 197, 202, 205, 207, 210, 218;
spectrum of Fomalhaut, 201;
composite spectra, 265, 266, 298;
diffuse lines in stellar spectra, 282;
duplicity of β Aurigæ, 291;
system of β Lyræ, 339, 340
Maw, black holes in sun-spots, 76;
submerged bridges, 79
Méchain, discovery of a nondescript nebula, 519
Mendenhall, characterisation of astrophysics, 9
Merope, brightness, 415;
attendant nebulæ, 416, 417;
suspected variability, 421;
spectrum, 532
Messier, description of Crab nebula, 518
Metalloids, in the sun, 29;
facility of spectral effacement, 34
Metals, in the sun, 26, 30;
in stars, 181, 182, 183, 184, 189, 195, 197, 201, 203, 209;
emission by in stellar spectra, 225, 234, 284;
absence from nebulæ, 278
Michelson, temperature and energy spectrum, 66
Milky Way, photographic study of, 7, 539, 540;
a distinctive spectroscopic region, 173, 542;
frequented by Wolf-Rayet stars, 187, 242, 543;
by helium stars, 196, 236, 543;
by carbon stars, 221;
by temporary stars, 396, 402, 543;
by gaseous nebulæ, 398, 506, 544;
by globular clusters, 448, 545;
problem of construction, 538;
dark openings in, 540, 541;
magnitudes of component stars, 542
Mira, character of spectrum, 185, 222, 223;
multiple hydrogen rays in, 224, 225;
radial motion, 224;
redness, 254;
vicissitudes detected, 348;
inconstancy of their method and amount, 349
Mitchell, hydrogen spectrum in Orion nebula, 499
Mizar, a spectroscopic binary, 289;
nature of system, 290
Monck, theory of temporary stars, 379;
preferential visibility of white stars, 543
Moon, projectile character, 2;
photographically studied, 7
Morin, drawing of the corona, 133
Motion-displacements of spectral lines, 4, 5, 286;
in the sun, 19, 38, 42, 105, 108, 109, 283;
in Mira, 224;
by rotation in stars, 280–283;
in binary systems, 288, 289, 291, 292, 295;
in eclipsing pairs, 300, 302, 303, 307;
in short-period variables, 320, 329, 334;
in β Lyræ, 338–341, 343
Müller, F., double nebula, 453
Müller, G. and Kempf, variability of ST Cygni, 325;
of U Vulpeculæ, 334;
of X Persei, 369;
photometric catalogue of the Pleiades, 421
Myers, system of U Pegasi, 332;
of β Lyræ, 341, 342
Naegamvala, photographs of flash spectrum, 46;
helium-absorption in sun-spots, 94
Nebulæ, connected with temporary stars, 384, 394, 395;
photographic surveys, 443, 449;
irregular, 506;
nondescript, 516–521;
variable, 522–530;
distribution, 544, 545
Nebulæ, gaseous, peculiarities of light, 173, 251, 536, 537;
helium emissions from, 174, 175, 491, 499;
radial velocities, 177, 470, 475, 483, 493, 499;
the matrices of stars, 271, 469, 486, 490, 495;
temperature, 502, 535, 536;
feeble luminosity, 532;
tenuity, 533, 534, 536;
meteoric hypothesis of constitution, 534, 535
Nebulæ, white, difficulty of spectral investigation, 174, 439;
spirality, 440–446;
rifted, 447, 448;
avoidance of Milky Way, 448;
double, 452–458;
clustering tendency, 458;
probable composition, 531
Nebular physics, inseparable from stellar physics, 171;
conditions of progress, 173, 174
Nebulium, absorptive incapacity, 465, 532;
denser than hydrogen, 476;
terrestrially unknown, 476, 502
Nebulous stars, luminous stability, 406;
Herschel’s notice of, 460;
distinction from planetary nebulæ, 461;
spectra, 462, 465, 467;
frequently compound, 463–465;
doubtful instances, 463–467;
desirable inquiries, 467, 468;
non-absorptive surroundings, 532
Newall, experiments on coronal rotation, 136;
duplicity of Capella, 294
Newcomb, constitution of the solar corona, 138
Nitrogen, absorption-lines in stellar spectra, 175, 181, 191, 195, 232,
235
Nordenskiöld, notice of clevite, 56
Nova Andromedæ, 385, 411, 450
Nova Aquilæ, nebular transformation, 386
Nova Aurigæ, photographic investigation, 175, 376, 382;
sudden rise, 375;
theories regarding, 377–379;
nebular phase, 379, 381;
light-curve, 380
Nova Carinæ, changes in spectrum, 383
Nova Centauri, apparition, 251;
spectrum, 384
Nova Cygni, nebular transformation, 382
Nova Normæ, photographic discovery, 382;
metamorphosis into a nebula, 383
Nova Persei (1887), spectrographic record of apparition, 384
Nova Persei (1901), sudden rise, 388;
blazing spectrum, 390;
light-curve, 391;
spectral alterations, 392, 393;
nebulous environment, 394, 395
Nova Sagittarii, spectrographic records, 385
Olbers, electrical theory of comets, 3
Omega nebula, conformation, 511;
alleged, change, 512
Oppolzer, solar absorption, 71;
meteorological theory of the sun, 164
Orbinsky, measurements of a globular cluster, 436
Orion nebula, helium-ray in spectrum, 174, 499;
photographic extensions, 190, 495–497;
nuclear star-group, 230–232, 495–497;
scattered stars in, 498;
hydrogen-radiations from, 499–502;
unknown ultra-violet line in spectrum, 502, 503;
suspected variations, 503;
variable stars in, 504;
low mean density, 533
Owl nebula, observational history, 472, 473;
photographs, 473
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.