LIBRARY
Diversity of California^
JRVINE
THE LIBRARY
OF
THE UNIVERSITY
OF CALIFORNIA
IRVINE
GIFT OF
MRS. THOMAS A. ROCKWELL
THE GREAT NEBULA IN ANDROMEDA.
(Roberts.)
THE
STORY OF THE
STARS
BY
GEORGE F] CHAMBERS,- F.R.A.S.
s-
OF THE INNER TEMPLE, BARRISTER-AT-LAW
AUTHOR OF
A HAND BOOK OF DESCRIPTIVE AND PRACTICAL ASTRONOMY,
PICTORIAL ASTRONOMY, ETC,
NEW YORK
McCLURE, PHILLIPS & CO.
MCMIV
COPYRIGHT, 1895,
Bv D. APPLETON AND COMPANY.
THE LIBRARY OF VALUABLE
INFORMATION.
A LIBRARY of useful information is a thing
needed alike in the family and in the office. In
this age of cheap printing the periodical daily,
weekly, monthly, annual brings forward an
enormous amount of half-digested reports of do-
ings in the world. Each report gives its results
in more or less technical language. There is a
special technique to each one of the natural
sciences and to each one of the departments of
history, of philology, jurisprudence, sociology, to
say nothing of the fine arts or literature.
A man or woman or youth who reads the
periodical carries away with him as a matter of
pure gain what he is able to seize and understand.
If ignorant of the technique, he gets very little
that is valuable.
This is the use of general information, to fur-
nish one with the technique, an outline of the
history of the investigation, and a summary of its
results.
I take as an illustration a volume from this
series of useful stories or brief summaries of his-
iv THE LIBRARY OF VALUABLE INFORMATION.
tory and results. " The Story of Geographical
Discovery," by Joseph Jacobs, contains in a com-
pact form, in its 200 pages of this i2mo volume,
a sketch of ancient and mediaeval geography ; of
the development of roads and commerce, the era
of search for routes to the Indies eastward, west-
ward, and northward, and finally the polar discov-
eries. Chapter XI gives an admirable summary
in fifteen pages of the exploration and partition
of Africa ; Chapter IX, twelve pages, of the par-
tition of America ; Chapter XII, seventeen pages,
an outline of polar discoveries.
A book of this kind read by the parents and
the older youth of the family furnishes the basis,
in many minds of the family, of accurate and
satisfactory information upon geographical mat-
ters. If the allusion in the newspaper or maga-
zine or the book of travels is given in technical
language with allusions to matters of history that
are not immediately intelligible, the little hand-
book is brought into requisition and the subject
is explained ; something worth learning has been
added to the mind.
In the twenty-four volumes that have appeared
at the present date the following volumes relate
to nature in its inorganic aspect. The books relat-
ing to the stars and eclipses, the earth, and to the
solar system, relate to cosmic nature. The stories
of a piece of coal, of the earth's atmosphere, of
electricity, of photography, relate to physics and
to physical processes.
In the volumes that relate to organic life
THE LIBRARY OF VALUABLE INFORMATION. V
that is, to plants and animals there is a story of
animal life, of the living machine, of the cotton
plant, of life in the seas, of germ life, and of
plants.
Relating to man and the instruments of his
civilization are the following: The story of the
art of music, of the art of building, of the alpha-
bet, of the British race, of King Alfred, of the
extinct civilizations of the East, of primitive man,
of geographical discovery, of books, and finally
the story of the mind.
To illustrate the usefulness of these books by
further example, take that on electricity. Elec-
tricity has, so to speak, been taken into the home
by the invention of the dynamo and of the various
kinds of cells for generation and storage of elec-
tricity. The book leads up from the most ele-
mentary beginnings to the complex results of the
present day, the final chapter relating to wireless
telegraphy. Perhaps the distribution of force
from great centres of power like Niagara Falls
or like the swift river tributaries descending from
the Sierra Nevada Mountains, and conducted by
wires to industrial centres where the raw mate-
rial of force is converted into light, heat, or
manufacturing power perhaps this is the most
important application of electricity. This is ex-
plained with great clearness in Chapter VIII. In
the days when the waterfall was the only consid-
erable source of power the manufacturing village
could choose its place only in the river valley.
With the possibility of transmitting power with-
VI THE LIBRARY OF VALUABLE INFORMATION.
out serious loss the raw material of force may be
utilized wherever needed.
Selecting a book from a number that relate to
man and his civilization, " The Story of King
Alfred," by Sir Walter Besant, there is presented
in a compact form a charming picture of the
beginnings of the English nation. It was very fit-
ting in 1901 that the English should celebrate the
millennial anniversary of the death of that great
king. There exists in England to-day a great
activity in the way of preparing and publishing
new local histories, not only of cities and towns,
but of counties, and also new editions of the
genealogies of the various families of the nobil-
ity of England. An interesting suggestion has
been made by President Jordan, of the Leland
Stanford Junior University in California, that
owing to the law of descent, by which each per-
son has two parents, four grand-parents, etc.,
that in the tenth generation back, counting his
parents as the first, there are more than one
thousand different ancestors if no allowance is
made for intermarriages. Reversing the calcula-
tion, the single ancestor should, in the tenth gen-
eration of descendants, have a thousand progeny,
in the twenty-first generation something over a
million, in the thirty-first generation more than a
billion, and in the forty-first, which would be
approximately the generation from King Alfred
in which the English people are living at the
present time, he would have a trillion of descend-
ants. Intermarriages, especially in former times
THE LIBRARY OF VALUABLE INFORMATION. Vll
when migration was very limited except among
royal families and families of the nobility, were
numerous. President Jordan suggests that all of
the people in southern England to-day are de-
scended not only from King Alfred, but also from
the peasant woman who found Alfred an indiffer-
ent servant in attending to the kitchen fire placed
in his charge during his exile. It is not only
possible, therefore, but quite probable, that the
majority of the people in the United States from
English descent will read in this " Story of King
Alfred " the history of an ancestor. " The Story
of the British Race " is noteworthy for containing
a careful study of the characters of each of the
ethnic threads that form the British people. Celtic
types of character receive most attention. " The
Extinct Civilizations of the East " presents in a
readable and instructive form a summary of
archaeological discoveries in recent times, with an
intelligent discussion of their significance in the
light of other sources of information. Still earlier
records that do not relate to prehistoric nations
so much as to prehistoric races are discussed in
"The Story of 'Primitive' Man."
The present day is a day of revolution not
only in machinery and the transfer of energy
from the place of its origin to the place where it
is needed, and of miracles both in organic and in
inorganic chemistry, but it is a day of revolution
in medicine and in the diagnosis of disease. The
study of bacteria in all parts of the civilized
world is making possible the cure and prevention
Vlll THE LIBRARY OF VALUABLE INFORMATION.
of those great scourges of the human race which
have their origin in infusorial life. The condi-
tions under which the microbe of some special
disease takes its origin and flourishes, as well as
those opposite conditions under which microbe
life becomes impossible, are one by one deter-
mined with accuracy by painstaking experiments
and verifications ; especially bacteria found in
malignant pustules; in cholera; in croup; in
diphtheria; in leprosy; in la grippe; in consump-
tion and scrofula ; in typhoid fever. One of the
most important books in this valuable series is
" The Story of Germ Life," by the Professor of
Biology in Wesleyan University. All of the adult
members in any family should read this book and
get a general acquaintance with the results it
describes. Ordinary books on hygiene are of
very little value as compared with this small
book which gives the history of the discoveries
in bacteria. Chapter VI, on the methods of com-
batting parasitic bacteria, is full of enlightening
information.
The study of bacteria, too, has proved of
great use in scientific agriculture. A very im-
portant agent in the growth of plants is nitric
acid. It would seem that there is ahead of us
great progress possible in the cultivation of
sterile soils, supplying to them what is needed to
make them rich, and especially supplying them
the nitric acid which is needed to convert them
into productive soils. " Plants, by building up
compounds, form the connecting link between the
THE LIBRARY OF VALUABLE INFORMATION. IX
soil and animal life; while bacteria, in the other
half of the cycle, by reducing these compounds
give us a connecting link between animal life and
the soil." There are several different kinds of bac-
teria that make nitrogen available for the nutrition
of plants. Chapter IV, on Bacteria in Natural
Processes, gives an account not only of this use,, in
the nutrition of plants, but also explains how it
is that the leguminous plants rival the best kinds
of meat in furnishing nitrogen compounds. Peas,
beans, and clover, " in a soil that contains no nitro-
gen products and watered by water that contains
no nitrogen will, after sprouting and growing for
a length of time, be found to have accumulated
a considerable quantity of fixed nitrogen in its
tissues. Careful investigation discovered that
these plants had a way of utilizing the secretions
of certain bacteria and thus obtaining nitrogen
from the air. Nearly four-fifths of common air
is nitrogen. The nests of bacteria found around
the roots of leguminous plants have a way of
extracting the nitrogen from the atmosphere
which permeates the soil, and of infusing it into
the juices of these plants. This discovery that
certain plants are generators of nitrates is one
of the most important discoveries ever made in
agriculture. It explains how the practice of the
farmer to keep the soil light by stirring it up,
hoeing and cultivating it, fills the soil full of
common air and thereby furnishes the elements
needed by the soil bacteria for the production of
nitrogen compounds.
X THE LIBRARY OF VALUABLE INFORMATION.
The relation of bacteria to the dairy industry,
an account of which is given in Chapter III, is
invaluable to the farmer.
In these days of what are called significantly
" sky-scrapers " the average citizen wishes to know
something in regard to the methods by which
these enormous structures can be built with
safety and even with greater solidity than the
old-style stone building of three and four stories
in height. It is cheap steel that has made this
possible. Large buildings for thousands of years
have been constructed with enormous walls of
masonry to hold up the inner framework of floors
and partitions, but the present generation has
discovered a method by which the framework
can be made strong enough with steel to hold up
the outside walls of masonry. The tall building
is, therefore, said to be not architecture, but en-
gineering with a stone veneer. The " sky-scraper "
has been called a steel bridge standing on end
with passenger cars running up and down within
it. The Park Row Building in New York has
nearly a thousand rooms and accommodates a
population of four thousand people. The enter-
prising and ambitious young person will learn
from "The Story of the Art of Building" how
to recognise the most charming types of church
architecture, and will acquire good taste in regard
to styles of buildings.
WILLIAM T. HARRIS.
WASHINGTON, D. C.,
October j, iqo2.
PREFACE.
WHEN invited to write this little book, I was asked so
to shape it that it should be a concise but readable out-
line of that branch of knowledge which one associates
with the expression the " Starry Heavens " liberally inter-
preted. I was to cater for those rapidly growing thou-
sands of men and women of all ranks who are manifesting
in these closing years of the nineteenth century in so
many ways and in so many places an interest in the facts
and truths of Nature and Physical Science. The task
thus imposed upon me was a very congenial one, and I
gladly undertook it. How far I have succeeded in pre-
senting my facts in a bright and cheery spirit others must
determine. But I would ask it to be understood that I
have dealt with facts rather than fancies. There are too
many of the former available for a writer on astronomy to
make it worth while to waste space in dealing with the
latter.
This volume will shortly be followed by another in the
same unconventional style entitled, " The Story of the
Solar System ; or, The Sun, Planets, and Comets popularly
described." I trust, however, that many of my readers
will not be content with these mere outlines of a noble
science, but will desire to obtain a more complete grasp
of the subject in all its bearings by studying first my
" Pictorial Astronomy " (Whittaker & Co., 2nd ed.), and
then my " Handbook of Astronomy " (Clarendon Press,
6 PREFACE.
4th ed., 3 vols.), which is a comprehensive treatise, yet
written in popular language and form so as to subserve
the wants of general readers. From both these works
thoughts and ideas have no doubt found their way into
the present volume.
For the chapter on the work of the Spectroscope in
connection with the stars I am indebted to my friend Mr.
E. W. Maunder, of the Royal Observatory, Greenwich,
one of the highest living authorities on this branch of
astronomy. G. F. C.
NORTHFIELD GRANGE, EAST BOURNE,
December, 1894.
CONTENTS.
I. INTRODUCTORY THOUGHTS g
II. FIRST EXPERIENCES OF A STARLIGHT NIGHT . n
III. THE BRILLIANCY AND DISTANCES OF THE
STARS 21
IV. THE GROUPING OF THE STARS INTO CON-
STELLATIONS 28
V. THE HISTORY OF THE CONSTELLATIONS . 39
VI. THE NUMBER OF THE STARS .... 43
VII. DOUBLE STARS 51
VIII. FAMILY PARTIES OF STARS .... 59
IX. COLOURED STARS 62
X. MOVING STARS 67
XI. TEMPORARY STARS 75
XII. VARIABLE STARS 83
XIII. THE STARS IN POETRY 95
XIV. GROUPS OF STARS 101
XV. CLUSTERS OF STARS 106
XVI. NEBULA 114
XVII. THE MILKY WAY 129
XVIII. THE SPECTROSCOPE AND THE STARS AND
NEBULAE 137
APPENDIX I. TABLE OF THE CONSTELLATIONS . 150
" II. LIST OF CELESTIAL OBJECTS FOR
SMALL TELESCOPES . . .153
INDEX 157
7
LIST OF ILLUSTRATIONS.
FIG. PAGE
1. The Great Nebula in Andromeda . Frontispiece
2. The Points of the Compass 20
3. Ursa Major and Polaris 31
4. Orion 43
5. a Herculis (double star) 51
6. C Herculis (1865) 54
7. Herculis (1871) 54
8. C Herculis (1883) 55
9. e Lyrae 60
10. <r Orionis 60
11. 8 Orionis 61
12. The Pleiades 104
13. 13 M. Herculis 107
14. 5 M. Librae 109
15. 80 M. Scorpii no
16. 67 M. Cancri 112
17. 77 M. Ceti (nebulous star) 113
18. The Ring Nebula in Lyra (Sir J. Herschel) . . 116
19. The Ring Nebula in Lyra (Earl of Rosse) . .116
20. The Nebula 43 1$ I. Virginis 117
21. The Spiral Nebula 51 M. Canum Venaticorum (Sir
J. Herschel) 118
22. The Spiral Nebula 51 M. Canum Venaticorum (Earl
of Rosse) 119
23. The "Owl" Nebula in Ursa Major . . . .120
24. The "Omega" Nebula in Scutum Sobieskii . 126
CHAPTER I.
INTRODUCTORY THOUGHTS.
" By the word of the Lord were the heavens made ; and all the
host of them by the breath of His mouth." PSALM xxxiii. 6.
No great while ago a defendant who had to appear at
a Court held at Carlisle arrived there true to his time ac-
cording to the local time at Carlisle appointed by the Court
for the sitting ; but he found that the Court had met by
Greenwich time, and in his absence had decided the case
against him. This was considered by certain gentlemen
" learned in the law " to be both a hardship and an illegal-
ity, and the poor man obtained a second chance of being
heard. Subsequently to this incident Parliament passed
an Act providing that whenever any expression of time
occurs in any Act of Parliament, deed, or other legal in-
strument, the time referred to shall (unless it is otherwise
specifically stated) be held, in the case of Great Britain, to
be Greenwich mean time, and in the case of Ireland, to be
Dublin mean time.
Quite recently the following incident occurred at Liver-
pool, the outcome of which, by the way, seems hardly
consistent with the statute just referred to. A levy was
made by the Sheriff's Order on the household goods of
some person who urged that, as this was done after sun-
set, it was illegal. The Director of the Liverpool Observa-
tory being called to testify to the time of sunset on the day
of the levy, the defendant's objection was upheld. The
conclusion appears unavoidable that, in noting the times
of sunrise and sunset, local time, and not Greenwich time,
2
10 THE STORY OF THE STARS.
must be regarded. This, as I have said above, seems not
to be consistent with the statute, but I am not concerned
here to discuss the question in that aspect. I only want
to use the facts referred to as a means of showing that
there is something more in the study of the stars than
many persons imagine. In other words, that in inviting
my readers to give a little thought to astronomical mat-
ters, I am asking them to consider things which are not
only not necessarily occult, difficult, or fanciful, but which
have in one way or another no 'slight bearing on business
and pleasures of life.
It is not necessary to develope the argument to any
great length, but it is just worth a passing thought, in con-
sidering the question whether astronomy has any, and if
so what, utilitarian value, to remember that those two ob-
jects of daily interest and use, the almanack and the diary,
entirely depend for their existence on the labours of the
astronomer in his observatory. In our case, as English-
men, these books are based on the labours of certain very
insufficiently paid members of her Majesty's Civil Service
at the Royal Observatory, Greenwich, and at the Nauti-
cal Almanack office in Gray's Inn Road. Were the staff
belonging to either establishment to resort to the fashion-
able expedient of a strike for higher pay (and there would
be much justification for their doing so), sooner or later
all the almanacks and diaries would cease to be published,
and the public business of the country would to a large
extent come to a standstill. But this is not all. The
shipping of England would come to a standstill, or nearly
so, and that not figuratively, but literally. Our vessels
would have to go back to the principles of navigation
practised by the inhabitants of these islands 2000 years
ago ; they would have to become coasting vessels, feeling
their way from place to place, and chiefly by daylight.
Long voyages oversea would be well-nigh impossible, or
FIRST EXPERIENCES OF A STARLIGHT NIGHT. 1 1
only to be executed in the face of the greatest risks and
the wildest chance. Our railway system would become
utterly disorganised. A few trains could run, but the in-
tervals between them would have to be considerable, and
they could only travel by daylight and at very low speeds.
These general thoughts will, I trust, serve as a suffi-
cient preliminary proof that there is more in the " Story of
the Stars " than lies upon the surface of things.
CHAPTER II.
FIRST EXPERIENCES OF A STARLIGHT NIGHT.
LET us suppose a would-be observer of the stars to
station himself on some fine evening soon after sunset in
an open and if possible elevated position. A varied and
striking, not to say picturesque, spectacle would soon un-
fold itself to his gaze. Stars invisible during the daytime,
because their light was overcome by the superior light of
the sun, would soon appear. They would become visible at
first only one by one, as it were ; then several would seem
to start into being, and finally their number would increase,
until it might be supposed that many thousands were visi-
ble, though in point of actual fact no more than about '
3000 stars at the outside can ever be seen by the naked
eye at any one time or place.
An attentive scrutiny, prolonged in one case for an
hour or two, and in another case for a day or two, will
disclose a twofold fact : first, that all the objects assumed
to be stars are moving in a body over the face of the sky
from hour to hour, whilst two or three brighter ones are
to be noticed which not only participate in the constant
movement from hour to hour of the whole mass, but have
an individual motion of their own in virtue of which either
12 THE STORY OF THE STARS.
from day to day, or in other cases from week to week,
they will be noticed to change their relative positions with
respect to the twinkling stars around them. Pausing for
a moment to distinguish between these two classes of
celestial objects, it may be stated that the bodies which
twinkle, and have (seemingly) no relative movement, are
the " fixed stars," properly so called ; whilst the others, it
may be only two or three in number on any given even-
ing, and which do not twinkle, are objects of a totally dis-
tinct character, and known as " planets."
Taking the sky as a whole, with its 2000 or its 3000
naked-eye stars, the observer (if in a northern latitude)
will notice, if he turns his back to the south, remembering
where the sun was at mid-day, that after successive inter-
vals, say of a of an hour, new stars are presenting them-
selves on the right, rising above the horizon. If he will
follow some one group in particular far into the night, he
will find that it gradually rises in the heavens in the direc-
tion from east to west. After a certain interval it ceases
to rise higher ; then descends on his left, and finally dis-
appears below the western horizon. This onward march
is not an attribute of all the stars quite in the simple form
thus mentioned, for of some of them it must be said that
they do not rise above the horizon nor sink down below
it, because they are always above it. Such are the stars
which face our observer, who with his back to the south
is looking towards the north. Of the stars thus circum-
stanced there are some which seem to describe a pathway
which scrapes, as it were, the northern horizon ; whilst
others seem to describe circular paths, which become
more and more contracted towards a certain star in par-
ticular. That star seems almost motionless throughout
the entire night, and is known as the "Pole Star." The
stars which are, as above stated, always above the hori-
zon, would always be visible during the whole 24 hours
FIRST EXPERIENCES OF A STARLIGHT NIGHT. 13
were it not for the sunlight. As a matter of fact, indeed,
the larger of them can on any fine day be traced by means
of a large telescope round and round during the whole 24
hours day after day throughout the year, weather permitting.
The movement of the heavens which has just been re-
ferred to is commonly called the "diurnal movement." A
better conception of it perhaps may be had if we imagine
(as indeed the ancients did) that we are in the centre of a
literal sphere ; that the stars are attached to the interior
surface of such a sphere ; and that it is endued from with-
out with a rotatory motion once in every period of time
which we designate a day of 24 hours. Regarding the
universe thus, we must, by one more forward stretch of
the imagination, consider the heavens to be always revolv-
ing around an invisible axis called the axis of the world,
which passes through the place of observation and a par-
ticular point near to the Pole Star. The direction of mo-
tion will be from east to west ; and whilst for us in Eng-
land the visible polar point of this imaginary axis will be
the North Pole, the other end of the axis will be pointing
in the opposite direction to another point called South
Pole. For the reader to obtain a full and true realisation
of these statements, which in the abstract no doubt have
a visionary sound, he must take a voyage to the Southern
hemisphere say, to the Cape of Good Hope or Australia.
Doing this, he will come face to face with a condition of
things which at first sight may be a little puzzling. He
will have lost both the North Pole and the Pole Star, and
also the constellation of the Great Bear and other constel-
lations which we associate with the north, and will find
himself called upon to study a very different situation. In
order to discover a polar point he will have to face the
south instead of the north ; he will find no bright star at,
or anywhere near, the South Pole ; and no Great Bear to
recall the memories of childhood and the nursery.
14 THE STORY OF THE STARS.
The remarks in the preceding paragraph will have
paved the way for the statement which must now be made,
that the study of the stars as regards their location in the
heavens is intimately mixed up with terrestrial questions
of geography ; in other words, that the observer's oppor-
tunity of surveying the fields of view afforded by the
heavens ever depends upon the latitude (not the longitude)
of his place of observation on the earth. Wherever he
may be, provided he be not immediately at the equator or
pole, he will have to consider the heavens as comprising 3
distinct regions, each with its own particular peculiarities.
The first, bounded by an imaginary circle called the " cir-
cle of perpetual apparition " ; the second, bounded by
another imaginary circle called the " circle of perpetual
occultation " ; the third being all the area not embraced
by either of the others. All the stars lying between the
first circle and the visible pole will be perpetually visible
to our observer throughout the year, barring of course
accidents of sunshine or weather. All the stars lying be-
tween the second circle and the opposite (or invisible) pole
will be perpetually invisible to our observer, because none
of them rise above his horizon. This is the condition of
things as regards an observer in the Northern hemisphere.
Looked at on the other hand from a station, say in Aus-
tralia, the converse of the foregoing will be the condition
of things. The stars perpetually visible in England will
be perpetually invisible in Australia, and the stars perpet-
ually out of view in England will be perpetually in view in
Australia.*
The reader will by this time quite understand that
* The statement in the text will only be absolutely and literally
true when the stations between which the comparisons are made are
in identical latitudes, the one north and the other south. For in-
stance, it would be about true of Dunedin, New Zealand, and
Geneva in Switzerland.
FIRST EXPERIENCES OF A STARLIGHT NIGHT. 15
when we talk about the celestial sphere, or the vault of
heaven, or the axis of the world, or the poles, we are re-
sorting to pure abstractions which are only calculated to
convey in a crude fashion ideas of apparent movements
which it is difficult to describe in words, or to indicate by
pictures, or to reproduce in model with mechanical appli-
ances. It may, however, be said that a pair of globes in-
telligently studied may be of some service. Perhaps it is
worth while to note in passing that ideas and expressions
on this subject which we employ simply as figures of
speech, were made use of by the astronomers of antiquity
in a literal and material sense. Many of them fully be-
lieved in the existence of a solid celestial vault with a ma-
terial axis provided with pivots turning in fixed sockets,
the stars being fastened to the surface of the vault by
nails or such-like attachments. Vitruvius may be men-
tioned as one of the best-known writers of antiquity who
has recorded as facts ideas of this sort.
It would not be in accordance with the design of this
little work to go very deeply into matters of the kind
brought under the reader's notice in the pages immedi-
ately preceding. Suffice it then to add that whilst the
longitude of an observer's position has nothing to do with
the question of whether he sees some stars and not others
on any given night, it has a good deal to do with the ques-
tion of what stars are visible at any given moment of time
to an American at New York, to an Englishman in Lon-
don, or to a Hindoo at Calcutta. For instance, when a
Londoner is going to bed at the hour of n p. m., the
New Yorker will be sitting down to his dinner at 6 p. m.,
whilst the Calcutta Hindoo will be preparing for breakfast.
The difference of 1 1 hours of absolute time which exists
between New York and Calcutta will result in each of
those places having a totally different batch of constella-
tions presented to its gaze ; because London occupies an
1 6 THE STORY OF THE STARS.
intermediate position, the Londoner will see certain stars
over his head which to the Calcutta Hindoo will appear
setting near the W. horizon, and which to the New
Yorker will appear low down in the E. horizon, just
rising.
Whilst it is intended as far as possible to exclude from
this volume matters of mathematics and geometry, there
are a few such matters which must be stated to and be
comprehended by the reader if he would follow up, to any
good purpose, the study of astronomy as a pleasant and
profitable occupation.
We sometimes have to speak of a body being in a
" vertical " position. This means " upright," and a heav-
enly body is in a vertical position when it is exactly over
the observer's head. The vertical of a place, then, is the
direction from which a body, set free to fall as it will,
seems to come when it strikes the earth at the place. It
is indicated by the direction of a string made fast at one
extremity, whilst the other extremity supports a weight of
some kind. Such a combination constitutes a plumb-line,
and is used by masons and bricklayers for the express
purpose of ensuring the uprightness or verticality of their
work. Further, it may be stated that the vertical of a
place is constantly perpendicular to the surface of water
there which is at rest.
The imaginary point in the sky where the vertical pro-
longed from the ground upwards meets the celestial vault
is the " zenith " of the place of observation. It is of
course the point exactly above the observer's head. If
one could conceive the vertical prolonged downwards
through the earth and coming out on the other side,* and
* The following " anecdote " illustrates this : An American in-
quired of as to the suitability of a certain soil for growing carrots,
said that they grew so well in it that the roots reached right through
to the other side of the earth, where people stole the carrots by pull-
FIRST EXPERIENCES OF A STARLIGHT NIGHT. 17
carried forwards till it met the celestial sphere at another
point, it would do so at a point which is called the " nadir "
of the observer on the upper side, so to speak, of the earth.
An observer standing out on an open plain, or better still
in a boat on the open sea, will notice that his view of the
land in the one case, and of the sea in the other, is cut off
from the sky by a circular boundary line, he himself being
in the centre of the circle. This circle is called the
" horizon." It really is a horizontal plane passing through
the place of observation at right angles to the vertical.
The " plane of the meridian " of a place is an imagi-
nary plane passing through what we have spoken of as the
axis of the heavens and the vertical of the place. Suitable
observation shows that the uppermost and lowermost
points in the circles seemingly described by all the stars
are situated in this plane. The intersection of this plane
of the meridian with the horizon to the north and to the
south constitutes what we call the "meridian line," or
simply the " meridian " of the place of observation. What
it is and what it means will perhaps best be grasped by a
consideration of the original meaning of the word. It
comes from 2 Latin words, through a single Latin word,
the words of origin being medtus middle, and dies, day
meaning in effect the point of the horizon immediately be-
low the place in the heavens where the sun is when it has
run half its daily course from sunrise to sunset.
With the horizon and the meridian understood, the
cardinal points, north, south, east, and west seem to come
naturally. An observer placed in the direction mentioned
at the beginning of this chapter, that is, facing the Pole
Star, will (in England) be facing the North ; immediately
behind him will be the South ; whilst on his right will be
ing them through by the tips, instead of pulling them up (as
usually done) by the tops.
1 8 THE STORY OF THE STARS.
the East and on his left the West. These words in Eng-
lish convey very little to us, but in their Latin forms are
much more expressive. The Latin, by the way, reappears
in the French. For instance, the Latin for " North " is
septentrto, which recalls the 7 (septem) stars near the
North Pole ; in French it is septentrton. Then the South
has already been mentioned and reaches us in French as
midi. Then the East is or tens (Fr. I' orient), z. e., the
place where the sun rises. And the West is occidens (Fr.
I' accident), z. e., the place where the sun falls, *. e., sets.
It is sometimes necessary to consider the position of a
star or the distance of one star from another by making a
measurement or an estimate along the plane of the hori-
zon, or along some other plane parallel thereto. This is
spoken of as a measurement in " azimuth " ; or, to put it
in another way, let us imagine a plane passing through
the zenith and through any star whatever ; that would be
at the moment of observation the azimuthal plane of the
star ; and the angle between this plane and the plane of
the meridian, or the star's distance from the meridian thus
measured, would be the star's " azimuth " at the particular
moment when the observation was made.
A few words respecting angular distances and their
measurement seem now needed, but they must be very
general because the study of angles is a matter which con-
cerns geometry in the first instance and astronomy only in
a secondary sense.
Every circle is considered to be divided into 360 de-
grees, every degree () being subdivided into 60 minutes,
and every minute (') into 60 seconds. Formerly every
second (") was divided into 60 thirds, but this method of
counting has become quite obsolete, and when it is neces-
sary, as it often is, to deal with fractions of a second, re-
sort is had to decimals. Occasions, indeed, sometimes
arise when it is convenient to go no further than whole
FIRST EXPERIENCES OF A STARLIGHT NIGHT. 19
minutes and to express as decimals of a minute the sec-
onds which we wish to record. Indeed, on occasions,
even the minutes and seconds taken together are set down
as simple decimals of a degree. Thus, 45 12' 20" might
be expressed as 45 I2'.33 or 45.2O5.
The whole circle being taken at 360, a half-circle em-
braces 1 80 ; a quarter circle, or " quadrant," is 90, whilst
the eighth, or " octant," represents 45. An intermediate
subdivision, a sixth, or " sextant," furnishes a word which
has an astronomical application, but it is to an instrument,
and not to the space which the word suggests. The
words " octant " and " sextant " as portions of a circle are
not in use, notwithstanding that the words themselves
exist.
Applying to the circle thus divided the 4 cardinal
points already mentioned we obtain the divisions which
constitute the dial of the " mariner's compass," and an at-
tentive consideration of the manner in which that is di-
vided will pave the way for a due comprehension of the
manner in which angles are measured for astronomical
purposes.
It will be seen by the diagram that if a circle is divided
into 4 quadrants we are furnished with the 4 principal
points, N., E., S., and W. Each quadrant therefore em-
braces 90 of the 360 which constitute the entire circle.
Dividing each quadrant into two halves gives us the sub-
divisions known as N.E., S.E., S.W., and N.W. Each of
these represents the half of 90, or 45. Then by subdi-
viding each half-quadrant into half again we obtain what
are quarter-quadrants, though no such phrase is in use.
The quarter-quadrants give us the points known as
N.N.E., E.N.E., E.S.E., S.S.E., S.S.W., W.S.W.,
W.N.W., and N.N.W.
We have now got our circle divided into 16 portions
each of 22^. The sailor, however, carries the matter 2
20 THE STORY OF THE STARS.
steps further, and by again subdividing into halves the
intervals just mentioned he arrives at the 32 " points of
FIG. 2. The points of the compass.
the compass," as they are called ; then by another sub-
division into halves he obtains 64 subdivision of the circle,
though the final appellation is not a " point," but a "half-
point."
Speaking generally, the subdivision of the circle for the
purpose of steering a ship does not need (except in special
cases, of course) any great refinement ; that is to say, an
order to vary a ship's course by half a point, or about 5^,
is precise enough on the open seas.* But the astronomer
in measuring angular distances in the case of the sun and
planets, and still more in the case of the stars, has to deal
* This remark does not apply to the larger steamers, whether
ships of war or belonging to the mercantile marine. These when
provided with steam-steering gear are steered to single degrees of
the circle.
BRILLIANCY AND DISTANCES OF THE STARS. 21
with arcs infinitely smaller than those which the " man at
the wheel " is concerned with. Not only arcs as small as
i", but even fractions of a second have to be taken into
account by the use of instruments far larger in size and
more finely graduated than the portable instruments, such
as sextants and theodolites, used by sailors at sea, and by
surveyors on land.
CHAPTER III.
THE BRILLIANCY AND DISTANCES OF THE STARS.
THE stars are not all equally bright, and custom has
divided them into certain classes known as " magnitudes."
The largest and brightest are said to be stars of the ist
magnitude ; next come stars of the 2nd magnitude,
and so on by a descending scale. Stars of about the
6th magnitude are reputed to be the smallest visible
to the naked eye, but by the use of telescopes we can
go on observing stars down to about the i5th magni-
tude or even smaller. It will be readily understood that
this is a very loose and arbitrary phraseology, but it has
become so consecrated by time and custom that it will
certainly never be set aside. Whilst everybody is agreed
as to what is the brightest star in the heavens, namely
Sirius, and that about 20 stars are worthy to be ranked as
of the ist magnitude, though less bright than Sirius, sharp
differences of opinion present themselves when we try to
mark off 2nd magnitude stars from ist magnitude stars,
and still more when we have to define where the 2nd
magnitude stars end and the 3rd magnitude stars begin.
Lower down in the scale the difficulties of classification
become infinitely greater they may, indeed, be said to be
hopeless.
22 THE STORY OF THE STARS.
Considering the love of precision and exactness which
characterises nineteenth-century science, it is somewhat
singular that so little has been done to submit to meas-
urement on definite principles the brilliancy of the vari-
ous stars, at any rate those visible to the naked eye.
Sir John Herschel made an attempt in this direction
about 60 years ago. Many years afterwards some Ger-
mans, especially an observer named Seidel, nibbled at it,
but Professor Pickering in America and the late Professor
Pritchard of Oxford, working at Oxford and in Egypt, are
the only two observers who have accomplished any results
worthy of the subject on a well-organised basis. Picker-
ing's labours at Harvard College Observatory, Boston,
U. S., have been published in the form of a catalogue of
4260 stars, whose magnitudes have been determined in-
strumentally on definite and intelligible optical principles.
Pritchard's catalogue comprises fewer stars than Picker-
ing's, but like its American rival is based upon philosophi-
cal principles, an instrument called the Wedge Photometer
having been employed. Both catalogues labour under the
disadvantage, that having been made in the Northern hemi-
sphere they do not include the whole area of the heavens.
Taking the stars as we find them, a very slight amount
of attention will show that not only are they of different
degrees of brilliancy, but that they are of different colours.
More prolonged and refined study will disclose the further
facts that some of them vary both in brilliancy and in
colour. These matters are of such extreme interest that
it will be best to devote a special chapter to them. The
brighter stars are distinguished from one another in vari-
ous ways, and many of them received in bygone times
quaint and curious names. At a very remote period they
were grouped into constellations, most of which survive
to the present time and are recognised to be of use to a
certain extent.
BRILLIANCY AND DISTANCES OF THE STARS. 23
Leaving the constellations for treatment in a separate
chapter, and confining our attention for the moment to the
stars as individual objects, it may be remarked that in
order to distinguish one star from another the ancient
astronomers often indicated a star by speaking of the posi-
tion it occupied in the constellation to which it belonged.
Thus Aldebaran was called Oculus Tauri, " the Eye of
the Bull." This custom was followed and largely de-
veloped by the Arabians, and many of the names invented
by them are still in use, corrupted or transformed. A
German astronomer named Bayer was the first to attempt
(about 1603) on any considerable' scale to simplify, and so
improve the old plan, but the Arabian names had, either
in their Arabian form, or as translated into Latin, taken
such deep root that many of them are even still in constant
use. Bayer's plan was to attach to the prominent stars of
each constellation the letters of the Greek alphabet, though
the popular idea that the opening letters of the alphabet
were reserved for the brightest stars and the later letters for
the less conspicuous stars, is unfortunately not universally
true. However the Greek letters a, /3, and y, do indicate
often the 3 brightest stars of a constellation. Bayer's
letters are still in vogue, the name of the constellation
being put after each in the genitive case. Thus the star
which bears the name of Sirius is termed a Canis Majoris,
Arcturus is a Bootis, and so on. The Persians are said to
have considered 3000 years ago that the whole heavens
were divided into 4 great districts, each watched over by
a " Royal " star. The 4 stars, each very brilliant and
remarkable, which occupied the important positions of
"guardians " of these districts were Aldebaran in Taurus,
Antares in Scorpio, Regulus in Leo, and Fomalhaut in
Piscis Australis, but Arago, who mentions this tradition, can
hardly be deemed accurate in his remark that the 4 stars
in question divide the heavens into 4 almost equal portions.
24 THE STORY OF THE STARS.
This chapter may be conveniently brought to a close
with a list in the order of brightness of the stars which
are commonly ranked as of the ist magnitude :
1. a Canis Majoris (Sirius).
2. a Argus (Canopus). Invisible in England and Northern
United States.
3. a Centauri. Invisible in England and United States, ex-
cept extreme southern points.
4. a Bootis (Arcturus).
5. Orionis (Rigel).
6. a Aurigse (Capella).
7. a Lyrse ( Vega).
8. a Canis Minoris (Procyon).
9. a Orionis (Betelguese).
10. a Eridani (Achernar). Invisible in England and
United States, except southern part of Gulf States.
11. a Tauri (Aldebarari).
12. $ Centauri. Invisible in England and United States,
except extreme southern points.
13. a Crucis. Invisible in England and United States.
14. a Scorpii (Antares).
15. a Aquibe (Altair).
16. a Virginis (Spica).
17. a Piscis Australis (Fomalhauf).
18. /3 Crucis. Invisible in England and United States, ex-
cept extreme southern points.
19. Geminorum (Pollux).
20. a Leonis (Regulus).
21. a Cygni (Deneb).
With respect to the first 13 of the above stars it may
be said that there is not much difference of opinion as to
their relative rank (though some authorities do make Vega
and Capella change places), but as to the remaining 7
there is not the same accord, some ranking Altair and
Spica before Antares, and Regulus before Fomalhaut,
Pollux, and /3 Crucis. These stars are pretty evenly dis-
BRILLIANCY AND DISTANCES OF THE STARS. 25
tributed between the Northern and Southern hemispheres,
for 10 are Northern and n Southern.
The following are the approximate dates on which
such of the foregoing stars as are visible in England and
the United States come to the meridian at midnight :
Procyon . . . January 14
Pollux . . . January 1 5
Regulus . . . February 21
Spica . . . April n
Arcturus . . . April 24
Antares . . . May 27
Vega . . . June 29
Altair . . . July 18
Deneb . . . July 31
Fomalhaut . . . September 3
Aldebaran . . . November 28
Capella . . . December 8
Rigel . . . December 8
Betelgueze . . . December 18
Sirius . . . December 31
Not entirely foreign to the question of the brilliancy of
the stars is the question of their distance. At the first
blush of the thing an uninformed reader might naturally
say that to measure the distance of a star from the earth
is impossible. But so far as the principle of this task is
concerned the problem is an easy one. It is in the prac-
tical working out of the principle that the difficulty lies ;
and this again rather arises from the extreme delicacy of
the measurements and necessary safeguards than from
any other cause. The process merely involves the taking
of certain angular measurements and applying to them
certain familiar theorems of trigonometry. It differs
scarcely at all from analogous operations which are car-
ried out every day on the earth by those engaged in land
surveying. What is involved will perhaps be understood
by considering what happens when a person enters a large
park at one end, intending to cross to the far side where
there are a number of trees in an avenue, passing en route
2 or 3 trees in the open. The trees in the far-off avenue
seem to be at no great distance apart, and the trunk of
one of them is nearly hidden by the trunk of one in the
3
26 THE STORY OF THE STARS.
middle of the park; but soon after the pedestrian has
started (perhaps when he has got over 50 yards) he notices
that the 2 last-named trees, which a minute or two ago
seemed almost in contact, are evidently some distance
apart, and after walking for perhaps another minute (say
another 50 yards) he sees cause to infer that a space of
perhaps 120 yards separates the trees which, before he got
in motion, appeared almost to touch. This transforma-
tion is the effect of " parallax," and the apparent displace-
ment of the trees is due to the real displacement of the
observer, owing to his having used his legs. But suppos-
ing the 2 trees singled out as above, instead of being
within the same park close at hand had been 2 miles off,
an advance of 50 yards would have caused so trifling a
displacement that, though a telescope provided with a mi-
crometer would have detected it, the naked eye might not
have done so. Why this ? Because in the first case the
distance traversed (50 yards) was a large fraction of the
distance (say 400 yards) at which the trees were situated
from the starting-point (as 50 : 400 : : i : 8). But in the
second supposed case the distance traversed (50 yards)
was but a small fraction of the whole distance (say 4000
yards) separating the pedestrian from the trees. The
proportion is now to be expressed thus : As 50 : 4000 : :
i :8o.
Let us apply these similes to the stars. An observer
on January ist is using his telescope when the earth is at
a certain known point in its annual orbit round the sun.
He determines the position of a certain star. He waits 6
months, and then, on July ist, again determines the place
of his selected star ; he finds it occupies the same place.
He is on July ist removed by twice the radius of the
earth's orbit, or 186 millions of miles, from the place he
occupied on January ist. If, notwithstanding this enor-
mous displacement of himself, the star seems to have un-
BRILLIANCY AND DISTANCES OF THE STARS. 27
dergone no displacement, our observer argues that the
star must be so far off that 186 millions of miles is a frac-
tional part of its distance, too small to be appreciable, just
as the 50 yards mentioned above is only a small fractional
part of 4000 yards.
The principle of all this has >een applied to several
hundred stars, but only about 2 dozen have yielded posi-
tive results. These results, so far as they go, seem to tell
us that the nearest star of those experimented upon is
a Centauri, and that the 4 next nearest are 61 Cygni, 21185
Lalande Ursas Majoris, Sirius, and p. Cassiopeia?.
Such standards as miles, or even millions of miles, are
quite unmanageable in dealing with distances such as
those which separate the nearest stars from the earth, so
it is customary to employ as the unit of stellar distances
the distance traversed by light in one year. Now light
travels at the rate of about 185,000 miles in one second, or
about 63,000 times the earth's distance from the sun in
one year. Applying these figures to the circumstances of
a Centauri, we find that as the parallax of that star is only
about f of a second of arc, a ray of light from it would not
reach the earth in less than 4^ years. This distance ex-
pressed in miles amounts to 24,750,000,000,000 ; and a Cen-
tauri is, so far as is known, the nearest star ! The reader
will hardly require any further explanation of the state-
ment made above that a mile is a hopelessly ineffective
and inadequate unit in which to express stellar distances.
It only remains to add that it is doubtful whether any of
the stellar parallaxes hitherto arrived at are accurate to
within -yV of a second of arc. Now -^ of a second is
the angle subtended by -fa of an inch at a distance of 10
miles ! Observations of stellar parallax, therefore, need
very first-class instruments and men, and it is on this ac-
count that the results up to the present time are neither
very numerous nor particularly consistent.
28 THE STORY OF THE STARS.
CHAPTER IV.
THE GROUPING OF THE STARS INTO CONSTEL-
LATIONS.
THE visible stars are. commonly treated as arranged in
groups which are called " constellations." The circum-
stances under which this grouping was brought about in-
volve so many interesting historical points that the history
of the constellations may well form a separate chapter.
Let me then limit the present chapter to a few general hints
and remarks on the finding of the constellations.
A reader who wishes to be able to do this with facility
must enter upon the study of the stars methodically, and
in accordance with a definite plan, and must be prepared
to persevere with his work at regular and not very long
intervals of time through an entire period of 1 2 months.
In making this suggestion I lay a good deal of stress on
the work being done systematically, and without any con-
siderable gaps of time in the doing of it. The importance
of this will be understood when it is borne in mind that a
given star comes to the meridian every night 4 minutes
sooner than it did on the preceding night. This has the
effect in the course of a fortnight of displacing a star by
1 5 of arc, the time of observation remaining the same. In
other words, if an observer wishes to see a given star on
the meridian a fortnight after his first observation of it,
he must take post at his telescope (supposing he is using
one which only works up and down in the meridian) one
hour earlier in the evening than the hour at which the first
observation was made. It would soon be seen in practice
why there was not only no advantage in thus altering
one's times but a positive disadvantage. The ordinary
object of a professed student would be, not to have a con-
stant change in the hours of his occupation, but to have
GROUPING OF STARS INTO CONSTELLATIONS. 29
a constant change in the occupation itself ; that is, in the
stars he is wishing to learn the names of, the hours of
work remaining (for his personal convenience) probably
much the same, say 9 p. m. to midnight.
There is another and also cogent reason for keeping at
this work regularly and avoiding long breaks. Though
the stars maintain, so far as they themselves are con-
cerned, speaking generally, the same relative positions
throughout the year, yet it makes a good deal of differ-
ence to the unpractised eye in the identification of par-
ticular stars whether they are looked at whilst they are in
the neutral position (as it may be called) of the meridian,
or when they are oblique to the meridian, eastwards of it
and rising, or westwards of it and setting. These differ-
ences can only be properly appreciated by being consid-
ered experimentally on a starlight night in the open air,
for no verbal account of them can be adequate.
A tourist who is travelling through a hilly country, un-
less he is a professional land surveyor employed on profes-
sional work, does not go through the formality of marking
off his meridian line and of setting out by an instrument
the bearings of particular peaks and towers for the pur-
pose of getting a record of them on paper. As a mere
traveller for pleasure he will probably have with him noth-
ing more than a map and a pocket compass ; and his aim
will be only to identify particular mountain-tops, church
towers, villages, or other objects of special interest.
There is only one way in which he will attempt to pro-
ceed. Assuring himself by means of his guide-book or
map, or by the aid of local information, of some one, two
or three prominent objects, the identity of which evidently
admits of no doubt, he will then feel his way by eye first
from one point and then from another point, constantly
consulting his map and compass. By some such process
as this, after starting with two or three objects recognised
THE STORY OF THE STARS.
to a certainty, he will be able to learn the names of all the
places within sight which he wishes to identify, to the
number it may be of several dozen.
This mode of procedure may be commended to the
would-be student of the Starry Heavens. Such an one
should obtain practice for his work by making sure at
starting of the names of two or three prominent stars.
He should then feel his way in between them by fixing in
his mind, one after another, minor triangles of stars, com-
paring every one with his map as he goes along, taking
particular care not to proceed with the identification of a
second triangle until he has quite satisfied himself that he
has accurately identified the stars forming the first.
It has already been mentioned that the practice has
long prevailed of designating the more conspicuous stars
in every constellation by the letters of the Greek alphabet.
An adequate knowledge of the small letters of this alpha-
bet is therefore an indispensable accomplishment for every
student of the starry heavens. These letters are :
a Alpha.
Beta.
7 Gamma.
8 Delta.
e Epsilon.
C Zeta.
T] Eta.
Theta.
Iota.
K Kappa.
\ Lambda.
/j. Mu.
v Nu.
{ Xi.
o O-mlcron.
IT Pi.
p Rho.
<r Sigma.
T Tau.
v Upsllon.
<f> Phi.
X Chi.
$ Psi.
a Omega.
I will now endeavour to apply the foregoing ideas to the
study of the stars, starting with the Great Bear as being
the most conspicuous of those constellations which never
GROUPING OF STARS INTO CONSTELLATIONS. 31
set In the latitude of London. The tail and hind-quarters
consist of 7 brilliant stars. Four of these (a, ft, y, 8) have
long been likened to a wain or waggon, the other 3 (e, , TJ)
being fancifully called the horses ; the 7 taken together
making " Charles's Wain " or the "Plough " to mention
some old English designations.* The hind wheels or the
2 stars (ft, a) farthest from the horses are called the
" Pointers," because they point towards the Pole Star (a
Ursae Minoris) at the tip of the Little Bear's tail. A line
carried from the Pointers beyond the Pole Star leads to
Cepheus and Cassiopeia constellations abutting on the
Milky, Way where it comes nearest to the Pole. Cassio-
t FIG. 3. Ursa Major and Polaris.
peia comprises several prominent stars which form a group
resembling the letter W or the letter M, according to the
* The popular name in the United States is the " Dipper." All
of the seven stars are not visible at their lower culmination south
of about the latitude of Philadelphia, but the two " Pointers" never
set at any place north of Charleston, S. C.
32 THE STORY OF THE STARS.
time of year at which they are viewed. The 2 northern-
most wheels of the waggon (8, a, Ursae Majoris) point to
the bright star Capella in Auriga, which is also circum-
polar in British latitudes, but not in the United States.
The stars of the Great Bear may be advantageously em-
ployed by the student as an approximate scale of angular
distances in making estimates of the distances between
star and star. Thus : The Pointer (a) nearest to the
Pole is 28f from it ; from ft to y is 8 , from f to rj is 7 ;
from 8 to e is 5^ ; from a to is 5 ; from y to 8 and from
e to is in both cases 4^.
Descending diagonally along the Milky Way from Cas-
siopeia towards Capella (a Aurigae) we come to a Persei,
and a little farther from the Pole we find Algol (J3 Persei),
a celebrated variable star in Medusa's head. If we carry
our eyes across the Milky Way in the opposite direction
we arrive at Deneb, the brightest star (a) of Cygnus (the
Swan) ; and beyond Cygnus, a little out of the Milky
Way, is Vega, the brightest star (a) in Lyra (the Lyre).
Draco (the Dragon) consists of a long winding chain of
stars running partly round Ursa Minor (the Little Bear).
In the space bounded by Cass^peia, Cygnus, and Draco,
lies'the constellation Cepheus.
Near Algenib (y Pegasi) and pointing directly towards
it are 2 conspicuous stars of Andromeda (a, )3), whilst a
3rd (y) lies a little beyond them. Andromeda will always
be readily known by reason of the connection of the bright
star (a) in her head with the large trapezium of Pegasus
(a, /3, y), the 4 stars forming the well-known " Square of
Pegasus."
An imaginary line projected through the Great Bear
and Capella passes to the " Pleiades," the celebrated group
in Taurus (the Bull), of which we shall have more to say
hereafter (in Chap. XIV. post), and then turning at a right
angle reaches Aldebaran (a Tauri, alias the "Bull's-eye")
GROUPING OF STARS INTO CONSTELLATIONS. 33
and the shoulders (a, y) of Orion. Orion is to the naked
eye by far the most magnificent of all the constellations,
whilst it is peculiarly rich in telescopic objects. Orion
may always be identified by the 3 bright stars in its
" Belt," which occupies the middle of a large quadrangle
of still brighter stars. Aldebaran is a reddish star, the
most prominent of the " Hyades," a cluster resembling the
letter V, and not far from the Pleiades. Aldebaran, the
Pleiades, and Algol (/3 Persei) make the upper, while Men-
kab (a Ceti), in the Whale's jaw, with Aries, make the
lower points of a large W. The head of Aries (the Ram)
is indicated by two principal stars (a, /3), the latter of
which has a small attendant.
An imaginary line drawn from the Pole Star and car-
ried midway between the Great Bear and Capella (a
Aurigas) passes to Castor and Pollux (a, /3 Geminorum),
two well-known stars in the heads of Gemini the Twins ;
whilst forwards to the S. of Gemini it will meet Procyon
(a Canis Minoris) the brightest star of the Lesser Dog.
From thence by bending the line across the Milky Way
and carrying it as far again it will reach Sinus (a Canis
Majoris) in the Greater Dog's mouth, and will then pass
to a somewhat conspicuous star, which in England is quite
in the southern horizon, a Columbae, 33 S. of the middle
star in Orion's belt.
Algol (/3 Persei) and Castor point to Regulus (a Leonis,
alias Cor Leonis, the " Lion's heart ") which is situated at
one end of an arc with Denebola 03 Leonis), the tuft of
the Lion's tail at the other end. S. of Regulus and pre-
ceding it, /'. e., coming to the meridian before it by about
hour, is Cor Hydras (a), the space between them being
occupied by the modern and insignificant constellation of
the Sextant.
The Pole Star and the middle horse of the waggon (f)
direct us to Spica, the brightest star (a) of Virgo, consid-
34 THE STORY OF THE STARS.
erably distant, whilst forwards, towards the horizon, we
shall reach Centaurus. The Pole Star and the first horse
(17 Ursas Majoris) conduct us nearly upon Arcturus in
Bootes (a), by which fine star, with Spica (a Virginis) and
Regulus (a Leonis), a splendid triangle is formed. Fol-
lowing at a distance to the southward is Antares (a
Scorpii), " the Rival of Mars," which with Arcturus and
Spica constitute another large triangle, having within it
the two bright stars, a and /3 Librae.
Corona Borealis, the Northern Crown, is nearly in a
line between Vega (a Lyrae) and Arcturus (a Bootis) ; and
the heads of Hercules and Ophiuchus lie between Lyra
and Scorpio. In the Milky Way, below the part nearest
to Lyra and on a line drawn from Arcturus through the
head of Hercules, is the bright star Altair in the Eagle (a
Aquilse), which makes with Vega and Deneb (a Cygni) a
conspicuous triangle. Closely following Aquila is a re-
markable group of stars forming the constellation Del-
phinus, the Dolphin.
The last and brightest (a) of the 3 principal stars in
Andromeda makes with 3 stars of Pegasus (a, /3, y) the
large " Square " or trapezium already mentioned, of which
the side formed by )3 and a points to Fomalhaut (a Piscis
Australis), situated in the mouth of the Southern Fish,
between the tails of Cetus and Capricornus.
The line of the ecliptic may without difficulty be traced
by the observer when his eye becomes familiar with the
stars now about to be enumerated. Not far from the
Pleiades are the Hyades with Aldebaran (a Tauri), a little
S. of the ecliptic. To the N. W. of Aldebaran at some
distance is the chief star of Aries (a) ; while to the N. E.
of that star are Castor and Pollux (a and /3 Geminorum).
Regulus (a Leonis) is on the line of the ecliptic; and
Spica (a Virginis) is but a very little to the S. of it. A
start being thus made with the ecliptic, the zodiacal con-
GROUPING OF STARS INTO CONSTELLATIONS. 35
stellations will be easily distinguished in their order from
W. to E. as follows : Aries lies immediately between
Andromeda on the N. and Cetus on the S., the three
asterisms reaching nearly from the horizon to the zenith ;
Taurus will be recognised by the Pleiades, Aldebaran (a)
and the Hyades ; Gemini, the highest of the signs as seen
in the Northern hemisphere, by Castor and Pollux (a and
|8) ; Cancer, by the historic group Prassepe, in the midst
of a waste rather void of stars ; Leo by the stars Regulus
(a) and Denebola (/3) ; Virgo, by Spica (a) to the S. of
Coma Berenices; Libra in mid-distance between Virgo
and the next constellation Scorpio ; Scorpio, by the red
star Antares (a) and its 3 other very conspicuous stars (/3,
8, jr,) ; Sagittarius as being the lowest (/'. e., most south-
erly) of all the signs ; Capricornus S. of the Dolphin ;
Aquarius under the neck of Pegasus ; and the Pisces be-
tween Pegasus, Andromeda, and Cetus. The following
familiar lines, though they do not rise to a high standard
of " poetry," are nevertheless very convenient as an aid to
the memory :
The Ram, the Bull, the heavenly Twins,
And next the Crab, the Lion, shines.
The Virgin, and the Scales ;
The Scorpion, Archer, and Sea-goaf,
The Man that holds the water-pot,
And Fish with glitt'ring tails.
The account just completed of what may be called a
" personally conducted " tour of the heavens, is at the best
a hasty and superficial performance, and I hope that the
bulk of my readers who have accompanied me thus far
will aspire to something higher and more exact, even
though there may be involved some details, the mastery
of which will require a certain amount of effort and appli-
cation.
36 THE STORY OF THE STARS.
A full list of the several constellations arranged in the
order in which they come to the meridian, that is to say
in the order of their Right Ascensions, will be found in
the Appendix ; but it is necessary to explain here what
the term " Right Ascension " means, and also what an-
other and allied term " Declination " means. Perhaps this
will be easiest done by means of a terrestrial analogy.
Everybody, I suppose, knows that Khartoum, the
scene of a grievous tragedy, is in Africa. But how many
of my readers could open an atlas, turn to the map of
Africa, and go straight with his finger-tip to the city of
Khartoum ? But if he knew beforehand that Khartoum
was situated in latitude 15 35' N. and longitude 32 30'
E. of Greenwich, the finding of it would be an easy mat-
ter, promptly accomplished by the aid of a network of
lines running up and down and across the face of the
map. Now what latitude and longitude are for terrestrial
geography, declination and right ascension are for celestial
geography (so to speak), only just a little different.
It is not difficult to make clear what declination is, but
an explanation of right ascension will not be taken in so
readily. We have already seen that the whole visible sky
is to be regarded as in some sense a sphere, with us, on
the earth, apparently as its centre ; and that the aforesaid
sphere turns on an imaginary axis directed to 2 poles.
Midway between the 2 poles lies the equator, and as it is
a semi-circle (or 180) from pole to pole the polar distance
of the celestial equator (which is the earth's equator pro-
longed to the heavens) will be 90. For some purposes
it is occasionally the practice of astronomers to count
angular distances from the N. pole towards the equator,
but the regular and ordinary practice is to count from the
equator to the poles, N. or S., as the case may be. Hence
we obtain the expressions " north declination " and " south
declination," as applied to the places of the stars, and
GROUPING OF STARS INTO CONSTELLATIONS. 37
these expressions are, in a certain sense, the counterpart
of the expressions " north latitude " and " south latitude "
used with reference to places on the earth.
The term " right ascension " is not to be brought home
to the mind quite so easily. In the case of terrestrial
longitudes there is no difficulty in finding a definite and
immovable terminus to start from. Many European na-
tions are using the meridian of Greenwich for this pur-
pose, though Frenchmen count from Paris, Germans from
Berlin, and so on. But in the case of the stars a fixed
zero is not so easy to find and still less easy to keep. How-
ever, astronomers have long been agreed to make what is
called the " First point of Aries," alias the " Vernal
Equinox," their starting-point for right ascensions. This
is the point where the sun, in the course of its annual
journey through the signs of the zodiac, crosses the equa-
tor, going from south to north, in the month of March on
the 2oth day of that month. The phrase " vernal equi-
nox " means the moment of equal day and equal night in
the spring.* It is also at this moment that the clocks
used by astronomers in their observatories read oh. om.
os. Owing to the operation of disturbing causes, the na-
ture and description of which do not belong to this chap-
ter, or indeed to this volume, this point is incessantly
shifting in the heavens. By virtue of a change called
"the precession of the equinoxes," the actual place of the
equinox goes backwards about 50" every year, and this is
what I meant by saying above that the zero for celestial
longitudes is not only not easy to find but when found
cannot readily be kept. It must suffice, then, for my
present purpose to remark that if we wish to fix the right
ascension of a star we must imagine a meridian to pass
through it ; then imagine a meridian to pass through the
* Lat. ver, spring ; ceguus, equal ; nox, night.
38 THE STORY OF THE STARS.
vernal equinox and note the angle which the former
meridian makes with the latter measured in degrees of
arc along the equator from W. to E. That angle will be
the star's R. A. It may be expressed either in degrees,
minutes, and seconds of arc ( ' "), or in hours, minutes,
and seconds of time (h. m. s.). The latter method is now
universally employed, the former having been discarded.
The relation of arc to time in connection with the
measurement of angles of right ascension will be readily
remembered by noting that a minute or second of time
represents a space of 15 times the corresponding denomi-
nation in arc, while the hour is 1 5 times one degree, that
is 15. The minute and second of time are denoted by
the initial letter of their names, whilst the minute and
second of arc are denoted by special symbols. Thus we
arrive at the following little table which the reader should
get clearly fixed on his mind :
i h = 15
i m = 15'
i* = 15"
i = 4 m
i' = 4 s
i" = o.o66
Perhaps this is as good a place as any at which to
warn the reader against a trap which he is very apt to fall
into. The " signs of the zodiac " are not the same as the
" constellations of the zodiac " (more often spoken of as
the zodiacal constellations). Twenty centuries or so ago
the astronomers of antiquity, with the 12 zodiacal constel-
lations within their knowledge, got into the natural and
not inconvenient habit of talking of the sun in its apparent
annual journey through the heavens along the ecliptic as
passing successively into and out of the several signs of
the zodiac. Each of these signs was regarded as occu-
pied by a constellation from which it took its particular
name. Commencing at the vernal equinox the first 30
through which the sun passed, or the region of stars in
THE HISTORY OF THE CONSTELLATIONS. 39
which the sun was located during the month following,
was called the sign Aries. The second 30 was called
the sign Taurus, and so on through the 12 signs, which
are identical in name and follow in the same order as the
existing 12 zodiacal constellations. Although there are
still 12 signs and 12 constellations, sign and constellation
no longer correspond. Though the sun when it crosses
the equator in the month of March enters the sign Aries,
it does not reach the constellation Aries till nearly a month
later. This discrepancy is due to the yearly accumulations
of 50* each which have been going on during the 20 cen-
turies mentioned and which are connected with the phe-
nomenon of the precession of the equinoxes already briefly
alluded to.
These preliminary explanations will suffice to enable
the reader now to settle down seriously to a study of the
constellations. This task must be carried out on starlight
nights with the aid of a good star-atlas * and a bull's-eye
lantern, assisted or not, as may be convenient, by an
opera-glass. In the Appendix will be found a Table of
the constellations, omitting a few insignificant modern
ones not generally recognised by astronomers.
CHAPTER V.
THE HISTORY OF THE CONSTELLATIONS.
To the grouping of the stars into constellations may
well be applied the legal phrase that the custom is so an-
cient that the memory of man runneth not to the contrary.
* I have found no English one as good as Keith Johnston's, edited
by Hind : and this because the stars show as white on a deep blue
background. Klein's, published by S. P. C. K., is also cheap and
very good.
40 THE STORY OF THE STARS.
The germs of it are evidently to be found in Holy Scrip-
ture. The three following passages, which I cite from the
Revised Version, whatever else may be said of them,
clearly imply that the allusions are to some well-established
usage :
" Which maketh the Bear, Orion, and the Pleiades, and the
chambers of the south.'' (Job ix. 9.)
" Canst thou bind the cluster of the Pleiades,
or loose the bands of Orion ? Canst thou lead
forth the Mazzaroth in their season ? Or
canst thou guide the Bear with her train ? "
(Job xxxviii. 31-2.)
" Seek Him that maketh the Pleiades * and Orion."
(Amos v. 8.)
The constellations now in use are about 80 or 90 in
number, counting a few minor ones devised during the last
century, chiefly for the Southern hemisphere, but by no
means counting all that have been proposed. It has been
well remarked : " Half a century ago no astronomer
seemed comfortable in his position till he had ornamented
some little cluster of stars of his own picking with a name
of his own making." Of the constellations now recog-
nised, no fewer than 48, and those including with scarcely
any exception the largest and best known, are recorded
by Ptolemy, and therefore have an unchallenged antiquity
of 2000 years, yet the date of the actual invention of even
one of them is quite unknown. Seneca attributed the
subdivision of the heavens into constellations to the Greeks
1400 years before Christ, but there is no proof of this, and
if it is permissible to draw inferences without having many
facts to go upon (a common practice nowadays), I should
be rather inclined to give some of the credit of inventing
* The Authorized Version has here "The Seven Stars."
THE HISTORY OF THE CONSTELLATIONS. 41
the constellations to the Chaldasans or Egyptians, or to
both of them in shares, the Egyptians having developed
that which they derived from the Chaldaeans, as the Chal-
daeans may have developed something they derived from
peoples which preceded them. Some writers, indeed,
have thought that a much greater antiquity should be as-
signed to the constellations, and there are not wanting
traces of proof to support this idea. Neglecting for the
moment the ancient constellations as a whole, it certainly
seems clear that a special degree of antiquity attaches to
the signs of the zodiac, and no wonder, seeing that they
remind us, amongst other things, of the apparent annual
path of the sun amongst the stars.
It seems more than probable almost certain that
the word " Mazzaroth " quoted above from Job xxxviii. 32,
and left untranslated in the text by the authors of the Re-
vised Version, means what they have suggested in the
margin, namely, the circle of the zodiac. And it is quite
consistent with this to find, as a modern writer has pointed
out, that : " These signs were known among all nations
and in all ages. From the almost antediluvian chronol-
ogies of China, India, and Egypt, to the traditions of the
recently discovered islands of the South Sea, traces of
them are discovered most clearly among the most ancient
and earliest civilised nations. In the remains of Assyria
they are recognised ; in those of Egypt they are perfectly
preserved ; in those of Etruria and Mexico they are trace-
able. This wide diffusion indicates a common origin,
both of the race of man and of the symbols of astronomy.
The love of symbols has been considered as natural to
man ; the creation amid which he is placed is symbolical.
Of this universal tendency the inventors of astronony seem
to have availed themselves, rendering it subservient to
man's spiritual education by familiarising to his mind the
lofty truths of Divine revelation."
4
42 THE STORY OF THE STARS.
" The earliest positive evidence of the primeval exist-
ence of the signs is in the Chinese Annals, where it is said
that the Emperor Yao, 2357 years before the Christian
era, divided the 12 signs of the zodiac by the 28 mansions
of the moon ; but it is not said that he invented them.
The Chinese national emblem of the dragon appears to be
the dragon of the sphere, which was at that time the polar
constellation, the brightest star in the dragon's head hav-
ing been the Pole Star in the antediluvian ages. The
Egyptians, on whose early monuments the signs are
found, acknowledged that they derived their astronomy
from the Chaldasans. The Chaldasans attributed their
science to Cannes, supposed to be Noah. The Arabs
and Brahmins, among whom astronomy was early culti-
vated, seem to have derived it from Abraham, through
Ishmael, and the children of Keturah. The Greeks sup-
posed their imperfect knowledge of the subject came
through the Egyptians and Chaldasans. The Romans are
thought to have received through the Etrurians the names
of the signs still in use among European nations. The
Etrurians are considered to have de'rived them, with their
other arts and sciences, from Assyria. The early Greek
poet Hesiod is said to have made use of Assyrian records.
He mentions some of the constellations by the names
they now bear. Cleostratus [circa 500 B. c.] was ac-
quainted with the signs, and wrote on Aries and Sagit-
tarius. A later Greek poet, Aratus, described the constel-
lations such as we now have them, and by equivalent
names. He gave neither history nor conjecture as to
their date, their meaning, or their origin. They were to
him, as to us, of immemorial antiquity."
The thoughts unfolded in the foregoing extract are of
great interest, but it is obvious that a thorough investiga-
tion of this subject would lead us far beyond the limits of
this little volume.
THE NUMBER OF THE STARS.
43
CHAPTER VI.
THE NUMBER OF THE STARS.
To say much that is definite about the number of the
stars is in one sense a very difficult thing to do if the idea
is to furnish any trust-
worthy or adequate
information on the
subject. The words
of Holy Scripture,
" Look now towards
heaven, and tell the
stars, if thou be able
to number them," *
cover much more than
appears at first sight.
To say that the stars
are innumerable is far
from being a mere po-
etic phrase ; it is in-
deed no more than a
prosaic matter of
fact. Nevertheless it
may probably surprise
some persons to be
told that according to
the estimate of the FIG. 4. Orion,
distinguished German
astronomer Argelander the number of stars visible to the
naked eye in the latitude of Berlin is only 3256, and must
be put no higher than about 5000 in all for the whole
heavens. Trie number to be seen becomes greater as we
* Genesis xv. 5.
44 THE STORY OF THE STARS.
approach the equator from the middle latitudes of either
hemisphere, owing to the wider expanse opened up to an
observer stationed at the equator. An observer located in
a place the latitude of which is o will see in the course
of the year all the naked-eye stars in the heavens.
Argelander's totals arranged in magnitudes are as fol-
lows :
Stars.
1st magnitude = 20
2nd " = 65
3rd " = 190
4th = 425
5th " = noo
6th " = 3200
7th " = 13,000
8th " = 40,000
gth " = 142,000
This matter has been made the subject of estimate by
various observers, including especially the late Professor
Grant of Glasgow and Karl Von Littrow of Vienna.
Their figures, though fairly accordant as regards naked-
eye stars in the aggregate, differ a good deal, magnitude
by magnitude, owing to there being no recognised defined
standards of magnitude.
As to this, however, it may be remarked as a thing by
the way, that Seidel, a German observer who has given
much attention to the matter, has suggested the following
as standard stars for the first 4 magnitudes :
ist a Aquilse, a Virginis, a Orionis.
2nd a Ursse Majoris, 7 Cassiopeiae, Algol (at max.).
3rd y Lyrae, 8 Herculis, 6 Aquilae.
, ( p Herculis, A. Draconis (too bright),
( H Bootis, 6 Herculis (too faint).
It may be well to point out that the statistics just given,
though necessarily somewhat approximate, are not to be
THE NUMBER OF THE STARS. 45
regarded as imaginary, though of course to count a num-
ber of points of light like stars is not in itself an easy task.
It may be worth while, therefore, to carry the foregoing
statements a little farther. A very painstaking astrono-
mer, also a German, Heis of Miinster, affirmed that it was
not possible to count more than about 5000 stars visible in
the sky available in Central Europe. Endowed with a sharp
sight, and adopting various artifices (such as shutting out
all artificial light and marking off by means of a great
black tube each region of the sky under examination), he
found himself able at Miinster to see 5421 stars. Inas-
much as he could from that one place in the course of a
year examine in succession T V ns f the heavens, he con-
cluded that supposing the portion of the Southern hemi-
sphere which he could not see resembled in a sense the
rest of the sky which he could see, the sum total of the
stars visible to the naked eye would mount up to about
6800. But it deserves notice that no possible number of
stars which could be counted would represent the stars
which an eye could discern. The eye can take notice of
more than it can count, because when any given star im-
prints itself upon the centre of the retina, others whose
images fall upon the corners of the eye, so to speak, seem
to vanish. This is a point as to which appearances are
apt to be very deceptive. It may be well here to remark
that it is important to distinguish clearly in the mind be-
tween the results of a single gaze at the sky, the eye being
for the while fixed, and a look all round. In the former
case it may be taken that no more than a space of 13 or
14 can be taken in simultaneously, whilst by moving the
eye methodically in successive directions the whole ex-
panse of the heavens may be brought under review.
Secchi noted the following experiment as one that he
often tried with interesting results. After taking a glance
at some particular part of the heavens he would transfer
46 THE STORY OF THE STARS.
his eye to the finder of the great telescope at the Roman
College at Rome, and would see in this subordinate tele-
scope, whose field was no larger than , as many stars as
were to be seen in the 13 or 14 grasped by the naked
eye. Passing then to his great telescope, armed with an
eye-piece showing only an arc of 15', or one-fourth the
area of the field of his finder, he would still see as many
stars as in the finder ; proceeding yet further to diminish
the field by increasing the power, the number of the stars
would scarcely diminish, because, though the area was
curtailed, yet the increased magnifying power revealed
minute stars which had previously escaped notice. Thus
it came about that in certain localities it was possible to
see in a field no more than ^ in diameter as many stars
as were visible to the naked 'eye in a field 13 in diameter.
This train of thought will readily enable the general reader
to realise the fact that the larger our telescopes become
the more stars we can discern ; in other words, that as we
cannot say for a certainty how large our telescopes might
become, so accordingly we cannot say when stars hitherto
unseen will cease to be invisible by becoming visible. So
that we may indeed say with Galileo that the stars are in-
numerable.
The heavens are not everywhere equally rich ; in many
places even with the largest^ instruments one can find in a
field of J scarcely 5 or 6 stars : it would not, therefore,
do to judge of the number of the stars by these excep-
tional regions. An effort was made by the two Her-
schels, Sir William in the Northern hemisphere, and Sir
John in the Southern hemisphere, to ascertain the possible
number of the stars. It is easy to understand that this is
one of the most gigantic tasks which an astronomer could
undertake, because it could never be completed in the
lifetime of one man. Sir W. Herschel adopted an indirect
method to arrive at his results. Making use of his ao-ft.
THE NUMBER OF THE STARS. 47
reflector, he directed it successively towards certain parts
of the heavens, chosen in irregular order, of which he
noted the right ascension and declination. These regions
were so distributed over the heavens as in a way to result
in the sky being dotted over with a network of surveying
stations equi-distant from each other. The field of his
telescope was just J, and the magnifying power 120. He
counted in each field the number of stars visible in it ; in
particular places where the number was so great as to
render counting impossible he made an estimate. Hav-
ing gathered together a certain number of these counts,
or estimates, in a particular part of the sky, he summed
up the total number of stars seen, and divided this total
by the number of the groups. The resulting figure was
taken to represent the mean average density of the stars
in the neighbourhood of the place examined. This meth-
od, the only one possible in practice, has some defects ;
still, employed on the large scale carried out by Sir Wil-
liam Herschel, it gave results so far conclusive that no
more modern effort has yet superseded it. Of course it
will often happen that a certain locality will be very rich
in stars, whilst in another like area, not far off, there will
be a great scarcity of stars ; still, taking rich and poor
neighbourhoods together, a fairly trustworthy average re-
sult will be obtained. It has already been stated that to
take a census of the whole heavens would be a work so
vast that no one man could ever hope to accomplish it ;
there is, however, now in progress an international photo-
graphic survey of the heavens, which, when it is complete,
will go far to fill up the void in our knowledge which at
present exists ; but before speaking of this it will be bet
ter to finish with the work of the Herschels in this depart-
ment of astronomy. To obtain an idea of it, it will suffice
to remember that Sir W. Herschel dealt with 3400 groups.
These were not all completely independent of one another,
48 THE STORY OF THE STARS.
and they must be reduced to the smaller number of 683 in
order to obtain the number of the quite independent
groups. Herschel is considered to have examined only
yfsth part of the sky ; it would have taken him 83 years
to have gone over the entire heavens, allowing that he
could have done 100 fields every night, and could have
found loo favourable nights in every year. In some re-
gions the stars were so numerous that Sir William counted
588 in one field of view, and, the telescope remaining sta-
tionary, field after field quite as rich passed along as in a
panorama for several minutes. At one place he estimated
that he had seen 116,000 stars passing before him in a
quarter of an hour ; and that on another occasion 258,000
stars passed in 41 minutes ; on the other hand, in other
parts of the heavens fields presented themselves with only
two or three stars in them. The results which Sir W.
Herschel arrived at were published in 1785. Nearly 50
years later his son, who went out to the Cape of Good
Hope for the express purpose of carrying on observations
in the Southern hemisphere, took up again this very self-
same question of the numbering of the stars. His results,
equally as interesting as his father's, differed from them in
this particular, that the Southern hemisphere is less uni-
formly decked with stars than the Northern hemisphere,
and bare places are more common.
By a computation based on the results of gauging
both hemispheres, Sir John Herschel found that the total
number of stars visible in an 1 8-inch reflector cannot be
less than 5J millions, but Struve, interpreting Sir W. Her-
schel's observations in the light of his own, estimated that
more than 20 millions of stars were within the grasp of a
reflector of the named dimensions.
The most cursory examination of the heavens will
make it clear that the stars are very unequally distributed ;
that in some parts they are very much more closely ar-
THE NUMBER OF THE STARS. 49
ranged than in others, and that this is true whether we
consider their absolute number or their individual bright-
ness. Various attempts have been made to frame specu-
lations as to the causes and meaning of these facts, but it
is obvious that all such speculations must be more or less
useless and unprofitable. I may have something more to
say on this subject when we come to deal with that won-
derful mass of stars which we call the Galaxy, or Milky
Way, but an investigation as to the " how " or the " why "
there are more stars to be seen in some places than in
others would, in jthe present state of our knowledge, lead
to no very definite or satisfactory results.
A few words about the International Photographic
Survey of the Heavens which is now in progress. This
took its origin from a Conference of Astronomers, repre-
senting 1 6 different nationalities, which met at the Paris
Observatory in April, 1887, on the invitation of the Acad-
emy of Sciences of France. The basis on which the
undertaking was started was in substance defined as fol-
lows : (i) That the progress made in astronomical pho-
tography demands that the astronomers of the present
day should unite in obtaining a permanent record of the
heavens by means of photography. (2) That the work
should be carried out at selected stations, and with instru-
ments which should be identical in size and other essen-
tial features. (3) That the principal object to be aimed
at is to secure a chart of the heavens for the present
epoch, and therewith data for determining with the great-
est possible accuracy the positions and brightness of all
stars down to a given magnitude, the ultimate idea being
that the information thus obtained should be so preserved
as to be available in future years for determining whether
changes of position or brightness have occurred in re-
spect of any given stars. These preliminary principles
having been accepted by the Conference, which comprised
50 THE STORY OF THE STARS.
20 representatives for France, 8 for England and the
British Colonies, 6 for Germany, 3 each for Russia, Hol-
land, and the United States, 2 each for Austria, Sweden,
and Denmark, and I each for Belgium, Italy, Spain, Portu-
gal, Switzerland, Brazil, and Argentina, a committee was
appointed to consider and report upon the form and size
of the instruments to be used and the range of magnitudes
to be embraced. After a large amount of anxious inquiry
and debate, it was eventually decided that the instruments
employed should be exclusively refractors of 11 inches
aperture, and rather more than 1 1 feet fo^al length, giving
a field of 2 square, the photographic plates being 6
inches square, and showing an effective square (reseau) of
51 inches, with lines \ inch apart.
The necessary instruments have been provided, chiefly
at the cost of the Governments of the respective countries,
and the survey is now well in hand at the following 19 ob-
servatories Helsingfors, Potsdam, Oxford, Greenwich,
Paris, Vienna, Bordeaux, Toulouse, Catane, Algiers, San
Fernando, Chapultepec, Tacubaya, Rio de Janeiro, Santi-
ago, Sydney, Cape of Good Hope, La Plata, and Mel-
bourne. These observatories range in latitude from 60
N. to 38 S., and may be considered as conveniently
placed for embracing the whole sky. It is scarcely neces-
sary to add that the work undertaken is one of enormous
magnitude, and, though not actually difficult, requires in
a high degree the services of observers well endowed with
the virtues of patience and carefulness. The work will,
of course, occupy several years.
DOUBLE STARS.
CHAPTER VII.
DOUBLE STARS.
WE have hitherto been considering the stars as iso-
lated points of light dotted hither and thither all over the
heavens and as if they had no connection one with an-
other. These suppositions are only true in a qualified
FIG. 5. o Herculis (double star).
sense, for the telescope reveals the fact that no inconsidr
erable number of the stars which we regard as simple
points of light are in reality 2 (or in some cases several)
single stars which are so close together as to appear to
the naked eye to be one.
52 THE STORY OF THE STARS.
The proximity of one star to another might in any
given case only be an effect of perspective and not an
actual fact. For instance, a man standing on the top of a
straight road which led up a hill might see 2 men ap-
proaching him, seemingly walking shoulder to shoulder,
as if they were 2 friends engrossed in conversation,
whereas in reality they might be isolated individuals walk-
ing up the hill, each on his own account, perhaps 50 yards
apart. On the other hand, if the man at the top saw the
other 2 men cross from one side of the road to the other
simultaneously, and that as one turned his head askew,
apparently to look at some distant object, the other did
the same thing, he might justly infer that the two were
really friends and were really walking side by side.
The foregoing illustrations will define with perfect ac-
curacy the difference between what is called an " optical "
double-star (that is, 2 stars which seem to be linked to-
gether because of the effect of perspective) and a " binary "
double-star ; that is, 2 stars which not only seem to be
linked together but truly are so. These last-named are
often spoken of as " physical doubles," or 2 stars physically
connected. To determine in any given case whether a
pair of stars belong to the one class or the other is a mat-
ter involving both delicate observations and laborious cal-
culations. More than a century and a quarter ago Michell
suspected that there might be a physical connection sub-
sisting between certain stars by considering the probable
chance of producing a purely accidental combination if a
batch of stars were, so to speak, promiscuously thrown
haphazard into space. He found that the chances of
bringing together stars such as the Pleiades, of their
brightness and at their distance, was 500,000 to I, of 1500
stars visible. The improbability became much greater if
the inquiry was based upon the case of stars of the 2nd
and 3rd magnitudes and within a few seconds of arc of
DOUBLE STARS. 53
one another. Yet in point of fact we have several exam-
ples of this kind, such as a Centauri and a Geminorum.
But probability does not suffice to establish the truth
of a fact. One draws a much more conclusive argument
from a consideration of the actual proper motions of the
stars where such can be detected. If the stars were acci-
dentally brought together, as they are generally of differ-
ent magnitudes, their proper motions, both real and ap-
parent, would also differ ; consequently with the lapse of
time they ought to separate from one another. Yet it
happens that many of these stars, though exhibiting con-
siderable actual motion, preserve very much the same dis-
tance from one another during an extremely long interval
of time. Such are the two stars composing a Centauri, a
Geminorum, y Virginis, Ursae Majoris, and a great num-
ber of others, pairs of unequal size, a Centauri, the two
constituent stars of which were separable with difficulty
in a telescope 100 years ago, has such a considerable
proper motion that the two stars ought now to have be-
come separated by an interval of 6 minutes if the proper
motion of the one were not shared in by the other. This,
perhaps, would not always be an unfailing criterion, be-
cause it might so happen that the proper motions only ex-
hibited small differences, notwithstanding the extent and
reality of the difference. What, after all, would in any
given case plainly decide the question would be the posi-
tive fact (where it could be established) that one star
turned around the other in a closed orbit in seeming ac-
cordance with the recognised principles of the law of
gravitation. This great discovery has indeed been made,
and we owe it to Sir William Herschel. When that re-
markable man had sufficiently perfected his instruments,
so that he could penetrate into the depths of space in a way
never before attempted by any of his predecessors, he set
himself the task of seeking to discover stellar parallax, or
54 THE STORY OF THE STARS.
the actual distances of the stars from the earth. He se-
lected for his purpose certain large stars which were
accompanied by small companions at a distance of only a
few seconds of arc. He measured these distances with
great care by means of an instrument of his own invention
called a " micrometer," which also enabled him to deter-
mine the angle made by a line passing through two stars
with the meridian. He called this angle the "angle of
position " of the two stars, regarding the larger of them
as the determining centre of the arc on which the meas-
urement was founded. If there had been any annual par-
allax that is to say, any apparent displacement of the
stars with respect to the celestial background, as a result
of viewing the stars from opposite points of the earth's
orbit at 6-monthly intervals that parallax would have
been discoverable because there would have been disclosed
a variation in the distance or angle, comparing one time
with another separated by the interval of 6 months. How-
ever, after numerous and painstaking researches, carried
IT
FIG. 6. Herculis (1865). FIG. 7. < Herculis (1871).
out with every attention to detail, Herschel could not sat-
isfy himself that he had obtained any proofs of change,
DOUBLE STARS.
55
and .he gave up the work for a time in despair. Having
afterwards improved his instrumental means, he resumed
his labours, hoping for better results. Great was his sur-
prise to find that some of the stars which he had formerly
seen double had become single, the junior member having
disappeared, whilst others had evidently changed both
their angular position and their distance. Though all
hope of discovering an annual parallax seemed to have
vanished, at least he had obtained traces of a parallax of
another sort, due either to a general movement of the
whole system or to some special movement appertaining
to particular stars. Michell's old idea seems to have re-
curred to Herschel's mind and to have stimulated him to
further effort, and after several additional years of pains-
taking and laborious work, at length in 1802 he found
himself in a position to announce to the scientific world
his grand discovery that there existed systems formed by
pairs of stars revolving about each other in regular elliptic
orbits. He coined the word
" binary " and gave it to
these stars, to distinguish
them from mere optical
double- stars, which do not
exhibit any mutual periodic
changes of place.
The interval that elapsed
between Sir W. Herschel's
abandonment of his first re-
searches and his renewal of
work was about 25 years.
This is a period quite suffi-
cient to enable the motion of
many binary stars to become evident to the senses, and
accordingly no fewer than about 50 stars were noticed by
Herschel to have undergone change during the time that
FIG. 8. f Herculis (1883).
THE STORY OF THE STARS.
his operations were suspended. True that his stars had,
for the most part, only had time to traverse a portion of
their orbits, but more than 90 years having elapsed since
Herschel's announcement of 1802, it follows that a certain
number of binary stars have not only gone entirely round
in their orbits once, but some of them have done so almost
twice, and the form and dimensions of their orbits are
now fairly well understood. To cut a long story short, it
may be stated that fully 200 pairs of stars are now recog-
nised to be in motion round one another in obedience to
laws probably identical with what are known as the laws
of gravitation, though for obvious reasons their orbits have
not all been investigated with equal completeness and
accuracy. The following are the names and particulars
of a few of the binary stars with periods of less than 100
years, the nature of whose movements has been ascer-
tained with fair certainty :
NAME OF STAR.
Period.
Date of Last
Passage.
Years.
42 Comae Berenices
25
1870
Herculis
34
1864
t\ Coronae
41
1891
fjf Herculis
45
i860
Sirius
49
1893
Cancri
59
1868
Ursae Majoris
60
1875
a Centauri
77
1875
y Coronae
85
1840
70 (/) Ophiuchi
94
1808
Sir W. Herschel's original observations had reference
only to pairs of stars, but the further attention which has
been given to this subject of late years has resulted in
the discovery of the fact that in certain cases there exist
systems of stars in triplets, each member of which sys-
DOUBLE STARS. 57
tern has a relation to the other two, which justifies their
being called not simply triple stars but " ternary " stars.
f Cancri is an object of this type.
It must be added, by way of caution, that though
movement on the part of a pair of stars during a course
of years is primd facie a proof of physical connection
involving motion in a closed orbit, yet this must not be
regarded as a rule of universal application. A mere an-
gular displacement may, in a given case, be the effect of
individual proper motion on the part of one or both of the
stars of a pair, and not the effect of a central force. From
this it will follow that sometimes the positions successive-
ly occupied by the principal star will not exhibit the line
of a sensible curve. Flamsteed's 6ist star in Cygnus
seems to be one of this character ; it is moving, but its
motion is in a straight line.
Before passing away from the subject of double stars,
a word should be said about the remarkable circum-
stances of 2 stars which are well known by reason of
their great intrinsic brilliancy Sirius and Procyon. Both
these stars are subject to peculiar disturbances of place,
which long excited the surprise and curiosity of astrono-
mers. It was suggested that these disturbances were due
to the presence of some invisible satellite, and in the case
of Sirius this surmise has proved well founded. In 1862
Alvan Clark, a well-known American optician, found near
Sirius a minute companion, the existence of which has
enabled astronomers to explain some, though perhaps not
all, of the irregularities found to exist in the positions of
the primary star at different times. Arising out of this
is the further conclusion that this faint attendant, which
has only T^^ of the light of Sirius, possesses a mass
more than of Sirius. In other words, unless it does
thus really approximate in mass to Sirius itself, it is not
capable of accomplishing the observed disturbances.
5
58 THE STORY OF THE STARS.
That disturbances are traceable in the movements of
Sirius is no new idea, for the great German astronomer,
Bessel of Kbnigsberg, as far back as 1844, not only no-
ticed their existence but suggested the presence of an in-
visible perturbing body, belonging to the system of Sirius,
as an explanation of the fact that the proper motion of
Sirius takes place not in a regular line, but in an irregular
sinuous line. Accordingly, he suggested that this very
bright star possessed a dark satellite. Other astronomers
worked at the idea, and may be said to have paved the
way for the actual discovery of the satellite by Clark.
A very interesting question often presents itself to
students of astronomy, who meditate on what they have
seen after they have examined double stars. The ques-
tion may be put in this form : We on the earth are
placed on a'certain moving body called a planet, which is
one of a number of planets circulating round the sun as
their chief ruler or centre. Is this state of things unique ?
Or, on the other hand, do other suns exist ? Or, to be
more precise, do other bodies exist in the universe which
are centres of life and motion analogous to our sun ? No
one who has seen a bright double star, with its one or
more companions, and still more, no one who has seen
the many bright stars with companions which are to be
found scattered up and down the heavens, can doubt
that the answer to the above main question must un-
doubtedly be in the affirmative. In other words, that
there are in the universe many suns, each with its own
cortege of planets, and not one sun only. Much beyond
this, however, we cannot go. One thing is not a matter
of speculation. Whereas our planets revolve round the
sun in orbits, which though not truly circular, are yet not
very eccentric ; that is, do not depart much from the cir-
cular form, yet in the cases of the binary stars, the orbits
of all that are known depart very much indeed from the
FAMILY PARTIES OF STARS. 59
circle. Secchi has well pointed out that if we consider
for a moment what is involved in the existence of lumi-
nous systems of stars, we may well be struck with the in-
ferences which necessarily follow. In the case of a sys-
tem the form of whose orbit is very eccentric (such as
a Centauri), any attendant planets must be warmed some-
times by 2 suns very near, sometimes by one sun very
near, and by another very far off. Who can calculate
the transformations of life which go on under such cir-
cumstances without remembering the wisdom of Him
who often with small apparent means is able to bring
about an infinite variety of results ? Add to this the fact
that double stars very often exhibit different and comple-
mentary colours. The imagination of even a poet would
be incapable of describing to us the phases of a day
illuminated by, say, a red sun, and of a night illuminated
by, say, a green sun ; or of a day in which 2 suns of dif-
ferent colours competed with one another, whilst the
night was ushered in by a golden twilight and the next
morning was preceded by a blue dawn. But I do not
wish in this chapter to drift into star colours, for that is a
subject of sufficient importance to deserve a chapter to
itself.
CHAPTER VIII.
FAMILY PARTIES OF STARS.
THE subject matter of the preceding chapter will nat-
urally suggest the idea that if one naked-eye star is found
telescopically to consist really of 2 stars, why not another
of 3 stars or 4 stars, or more, in close association physic-
ally or apparently ? And such, indeed, is the case. We
have, accordingly, plenty of triple stars, some quadruples,
some quintuples, some sextuples, and so on many of
60 THE STORY OF THE STARS.
them very picturesque to look at through a telescope.
Amongst the triple stars within the easy reach of amateurs
armed with small telescopes
may be mentioned Flamsteed's
II Monocerotis, 12 Lyncis, and
51 Librae. The following are
quadruples : TT' Canis Majoris,
8 U Lacertae. /3 Lyras is a quin-
tuple. Again there are some
stars which comprise so many
constituents that they can best
be described as " multiples " ;
such are e Lyra? and a- Orionis.
FIG. 9. * Lyrse. - ... , , .
It will be seen from the en-
gravings that each of these exhibits a double system of
stars, so that f Lyras may be called a double-double, whilst
<r Orionis is a double-triple. The former object comprises
FIG. 10. 9 Orionis.
FAMILY PARTIES OF STARS.
6l
one pair of stars of mags. 5 and 6$, whilst the second pair
are 5 and 5^ respectively. There seems every reason to
suppose not only that the 2 stars of each pair constitute
a binary system (each star revolving round the other),
but that each pair taken together revolves round the
other pair, thus constituting a double-binary, or a system
FIG. IT.* Orionis.
of mutual association of great complexity. Between the
2 main pairs there are several smaller stars. Many tele-
scopes will show 3, and Professor Hall, in America, has
made the 3 into 7, but his additional stars are very faint
indeed, and can only be seen in the very largest telescopes.
Lyrae is on the frame of the Lyre, i$ N. E. of the very
bright star Vega.
The group forming tr Orionis, whilst it bears a certain
62 THE STORY OF THE STARS.
family resemblance to e Lyrae, differs from it in the respect
that we have no knowledge of any of the stars being
linked together so as to constitute a moving system, a-
Orionis may be easily found, as it forms the southern ver-
tex of a triangle with the 2 last stars (f and t) in Orion's
Belt ; and it is rather less than a degree from f in the
direction of ft.
Orion contains another multiple star of great interest
known as 6 Orionis. In this case there are 6 stars, the
four most conspicuous of which make a trapezium at dis-
tances not very unequal. The $th and 6th stars are fainter,
and lie just outside the boundary lines of the trapezium.
In this case the component stars are not organised in
pairs, and do not appear to constitute a system physically
connected. 6 Orionis is in the midst of the " Great Nebula
in Orion," of which more anon. Perhaps it might even
be said to form a part of the nebula.
CHAPTER IX.
COLOURED STARS.
MOST persons would say on a casual glance that the
stars are specks or points of white light, and so no doubt
the majority of them are ; but more attentive examina-
tion will disclose the fact that a very considerable number
of them exhibit definite colours, though those in which
any colour is very pronounced are in a great minority.
The student who is familiar with the intense colours of
the solar spectrum will be disappointed if he expects to
find amongst the stars many colours as pronounced as
those which he sees in the solar spectrum. Neverthe-
less, it is possible in a general way to find here and
there stars which if they were all brought together in
COLOURED STARS. 63
a row would constitute some similitude of the solar spec-
trum.
There are many difficulties in the way both of observ-
ing and of recording the colours of stars, and this ex-
plains the discrepancies in the accounts put forth by dif-
ferent observers. In the first place, people's eyes are
differently constituted ; some eyes are more capable than
others of accurately appreciating and describing a colour.
Some eyes, indeed, as is well known, are totally incapable
of appreciating certain colours at all. Possessors of such
eyes are said to be "colour-blind." But, disregarding ex-
treme cases of this sort, it is quite certain that ordinary
eyes will differ not a little in appreciating a given colour.
It suffices to visit a picture gallery and take note of the
differences in the copies of one and the same original pic-
ture which are being made by different copyists, to realise
the fact that particular hues in the original are reproduced
in a very different way by the different persons.
Then, again, the quality of the glass of the telescope
employed influences much the apparent colours of the
objects looked at ; and still greater is the effect of the good
or bad grinding of the lenses. In other words, lenses
made of very pure glass and very accurately ground and
polished will yield images and indications of colour which
will be much more true to nature than the indications
afforded by inferior glass inaccurately figured. It is a
very noteworthy fact that metallic mirrors always give to
objects seen through them a reddish tinge. This is strik-
ingly brought out in connection with Sir John Herschel's
observations of red stars. To many of these objects he
has attached such qualifying words as "carmine," " ruby,"
"intense crimson," where ordinary observers employing
ordinary telescopes would see only ordinary red hues.
Nor is magnifying power entirely an unimportant matter ;
with a low power white will dominate, and other tints will
64 THE STORY OF THE STARS.
in a measure be lost, because no star is absolutely mono-
chromatic ; on the other hand, a high magnifying power
diminishes the total light, and, exaggerating the dimen-
sions of the spurious discs, renders the colours more easily
distinguishable. Again, the state of the atmosphere and
the proximity of a star to the horizon greatly affect its ap-
pearance. It is only when a star is well up in the heavens
above the horizon that its true colour, whatever it may be,
can be noted, because near the horizon all celestial objects
apparently acquire red or orange hues, which do not really
belong to them.
Perhaps the greatest of all the difficulties which beset
the observer who wishes to make an accurate record of
star colours, is the difficulty of providing and using a
standard of colour for comparisons. Such a standard is
furnished naturally by the solar spectrum ; but astrono-
mers have hitherto been altogether baffled in their at-
tempts to reproduce the prismatic colours in such a way
that they can be rendered practically available in the dark-
ness of night, side by side with the image of a star pro-
duced at the eye-end of a telescope. There is herein, in
point of fact, a double difficulty : that which may be called
the manual or mechanical difficulty just alluded to, and
that which arises from the fact that the artificial light em-
ployed by night being yellow, injures the neutrality of the
eye and falsifies all artificial colours. It was with the idea
of getting over these difficulties that Secchi proposed to
make use of an electric spark, which, if derived from dif-
ferent substances, would give for each of them a different
hue, but I am not aware that any attempt has ever been
made to put this idea into practice.
Single stars of a red or orange hue are not uncommon,
but isolated blue or green stars are very rare. Indeed,
ft Librae appears to be the only conspicuous star which is
green. In the case, however, of double stars it is much
COLOURED STARS. 65
more easy to define their colours, for in many instances
they exhibit very well-marked colours, and frequently the
colours of the 2 stars are what are called " complemen-
tary." The reader may be reminded that this is a term
applied by physicists to the colours which, when united,
make white light. In order to obtain a strictly exact idea
of what these colours are recourse must be had to a spe-
cial instrument of which several kinds have been con-
trived. But for the elementary purposes of this work it
will suffice to state that the principal pairs of colours which
are mutually complementary are red and green, orange
and blue, and yellow and violet. The intermediate tints
are too innumerable to be described in words, and they
can only be realised by instrumental means.
When we speak of double stars as exhibiting different
colours it is not permissible in all cases to regard the
colours as an optical illusion or an effect of contrast, for
in some instances certainly the colours are an actual
physical reality. We may draw this conclusion in some
cases from the circumstance that the colours seen are not
always complementary ; and in other cases from the fact
that, by concealing the principal star by means of a bar
in the eye-piece, formed of watch-spring or something of
that sort, we shall notice that the companion star, when
thus cleared of the effects of its primary, preserves its
colour unchanged.
The following may be mentioned as good examples of
coloured pairs
Large Star. Companion Star.
T> Cassiopeise . . . Yellow Purple
a Piscium . . . Pale Green . . . Blue (or var.)
7 Andromedse . . . Orange Green
t Cancri Orange Blue
e Bootis Pale Orange . . . Sea Green
fCoronae... ... White Blue
66 THE STORY OF THE STARS.
a Herculis . . . Orange Emerald Green
/3 Cygni Yellow Sapphire Blue
a Cassiopeiae . . . Greenish . . . Bright Blue
Secchi compiled the following list of conspicuous stars
of the colours stated : White, Procyon, Altair ; Blue,
Sirius, Vega, Castor, Regulus ; Yellow, Capella, Pollux,
a Ceti ; Orange, Aldebaran, Aicturus, Betelguese ; Ruddy,
Antares, a Herculis.
Kriiger, an experienced German observer, has given
the following list, which, it will be seen, is not wholly
in accord with Secchi's: White, Sirius, Altair, Regu-
lus ; Yellow, Capella, Pollux, Arcturus ; Orange or Red,
a Herculis, Betelguese.
All the really red stars that is, stars of pronounced
depth of colour are comparatively small in size scarcely,
if at all, visible to the naked eye. There are a few per-
haps half a dozen to which the designation " carmine "
may be applied, but the bulk of the so-called red stars are
more orange than red. I shall have something more to
say about some of these in the chapter on " Variable
Stars."
The question of whether the stars vary in colour has
attracted some attention, but the evidence is on the whole,
meagre and inconclusive. From a passage in Seneca, an
ancient Roman writer, it has been inferred that he wished
it to be understood that in his day Sirius, the Dog Star,
was red, whereas now it is white, or bluish-white. Ptolemy
seems also to have regarded Sirius as a red star, and to
have used a word to describe it which he also applied to
Pollux. Now Pollux is certainly a reddish-yellow star in
the present day, and if it and Sirius could ever have been
appropriately designated by the same adjective of colour,
then the conclusion follows as a matter of course that
Sirius no longer exhibits the colour it once did. Capella
MOVING STARS. 67
is perhaps another star which has changed from red, or
reddish, to blue but one could have wished for a larger
number of instances. At present we can only say
that whilst change of brilliancy in the case of stars is a
common occurrence, change of colour is not a well-estab-
lished fact.
CHAPTER X.
MOVING STARS.
THE term " fixed stars " is a familiar one, and in a
certain sense it is the expression of a truth, but modern
science has shown that the term, as applied to the stars,
needs to be employed under reserve, for a great many
stars are not "fixed." I am not, of course, alluding to
their apparent annual or diurnal movements : we have
considered that matter in a previous chapter, and I hope
the reader understands by this time (at any rate generally)
what these apparent movements are and how they arise.
What we have now to deal with is actual proper motion,
and with this a considerable number of the stars are en-
dued.
It must be understood, of course, that though the an-
cients divided the stars into two classes those which
were stationary, and those which moved they knew
nothing of the stars which form the subject of this chap-
ter being moving stars. The objects to which the an-
cients applied the designation of " wandering stars " were
what we now call Planets, or Comets. Indeed, the very
word " planet " itself is derived from a Greek word mean-
ing " a wanderer." What we have now to consider are
the movements of certain stars, which movements are, as
a rule, very small in amount, and proceed very slowly.
Sir John Herschel's statement of the case can hardly be
68 THE STORY OF THE STARS.
improved on. He says : " Motions which require whole
centuries to accumulate before they produce changes of
arrangement such as the naked eye can detect, though
quite sufficient to destroy that idea of mathematical fixity
which precludes speculation, are yet too trifling, as far as
practical applications go, to induce a change of language
and lead us to speak of the stars in common parlance as
otherwise than fixed. Small as they are, however, as-
tronomers once assured of their reality have not been
wanting in attempts to explain and reduce them to gen-
eral laws."
What the expression the " proper motion " of a star
means or involves may perhaps be best understood by
some such illustration as the following : A man standing
in Trafalgar Square and looking down Whitehall may at
a given moment see in the direction of the Houses of Par-
liament an omnibus, a cab, and a van. After an interval
of 2 minutes he may see the same vehicles, but their order
may be first the van, then the cab, and lastly the omnibus.
This may imply either (i) that the van has remained
stationary, the omnibus and the cab having moved for-
wards, the omnibus travelling at a more rapid pace than
the cab; or (2) that all three have moved somewhat, but
each at a different pace ; or (3) that the van has backed
towards Trafalgar Square, only the omnibus and the cab
going forward. If such a condition of things were con-
ceived to be transferred to the heavens, our ideal omnibus,
cab, and van being transformed into stars, we should have
an analogue of the problem which the astronomer has to
solve in detecting and valuing the proper motions of 3
neighbouring stars, or, it may be, of only 2, or perhaps
even of only i, of such stars. Be it remembered, too,
that in the illustration I have given it may well happen
that the Trafalgar Square spectator, from his position
astride of one of Landseer's lions, though he may be quite
MOVING STARS. 69
sure that the omnibus and the cab have both moved for-
wards, may yet be totally incapable of determining whether
their movement amounts to 10 yards or 50 yards, because
he is viewing the whole proceeding " end on," or, in as-
tronomical language, the 3 vehicles are nearly in his " line
of sight." Things would, however, present quite a differ-
ent aspect to a second spectator standing, say, in front of
the Horse Guards. His would be a " broadside " view of
the several vehicles ; and whether they had all moved, or,
if only some of them, then which of them, and how much
had each moved, would be points upon which he could
pronounce an opinion promptly and (let us hope) accu-
rately.
The above simile in each and all its stages and as-
pects may be taken to be a counterpart of the problem
presented to an astronomer called upon to investigate
stellar proper motions. And what Fontenelle once said
in respect of the star known as Altair in the constellation
Aquila is in keeping with the illustration which I have
borrowed from what may be seen any day at Trafalgar
Square. Said Fontenelle : " There is a star in the Eagle
which, if all things continue their present course, will,
after the lapse of a great number of ages, have to the
west another star which at present appears to the east of
it."* Fontenelle's remark is just such a remark as my
ideal spectator at the Horse Guards might make because
of his enjoying a " broadside " view of the changes in the
positions of the vehicles going down Whitehall. But the
* Referring to the diagram of the stars in Ursa Major, given on
p. 36 (ante), it may be noted that all 7 are endued with proper mo-
tion ; but whilst ft, y, 8, , are moving one way, a and 17 are moving
the opposite way, and Fontenelle's remark (varied as necessary)
finds a further exemplification. Various examples may be found of
stars in proximity having common proper motions or, as Miss
Clerke words it, having a "gregarious tendency."
70 THE STORY OF THE STARS.
original spectator at the Nelson Monument has also his
circumstances reproduced in the heavens ; for, even though
in the case of any given star no indications, or but slight
indications, of lateral change of place can be detected, yet
such star may nevertheless be endued with a rapid mo-
tion of either approach or recession which can be found
out by a secondary method. Thanks to the spectroscope
and the ingenuity of modern astronomers, motions of ap-
proach to or recession from the earth have been discov-
ered in the case of certain stars, notwithstanding that
those stars, being seen " end on " (alias, in the line of
sight), seem on mere visual observation to be practically
stationary.
But I am anticipating too much. The fact that certain
of the stars are endued with a proper motion of their own
was first ascertained in 1718 by the English astronomer
Halley. By comparing the positions of Sinus, Arcturus,
and Aldebaran, as laid down in the most ancient cata-
logues, with the positions determined by himself in 1717,
he found, after making every allowance for the effects of
precession and the variation in the obliquity of the ecliptic,
that these stars seemed to have got out of place to the
extent in each case of more than \, a displacement too
considerable to be ascribable to errors of observation or
errors of copying. In the case of Aldebaran it was further
found that that star had undergone at Athens in 509 A. D.
an occultation by the Moon which could not have taken
place if the star had occupied 1400 years ago the same
or nearly the same place that it occupies at the present
time. The utmost that Halley could do was to surmise
that the stars in question were affected by proper motion,
because in those days no long-continued series of observa-
tions of places taken by exact instruments were in exist-
ence. Such observations, however, soon began to accu-
mulate as the 1 8th century rolled on, and accordingly in
MOVING STARS. 71
1738 James Cassini was able to say with some confidence
that Arcturus had undergone a displacement of 5' in a
century and a half, whilst the neighbouring star rj Bootis
had been exempt from such displacement. Inasmuch,
however, as precise and exact instrumental observations
of star places can only be said to date from 1760 (being
the epoch of Bradley's Catalogue of important stars) and
as that was only a century and a quarter ago it is evidently
clear that the study of stellar proper motions must be re-
garded as a branch of the science which is still in its in-
fancy, especially seeing that in the case of the star having
the largest known proper motion (1830 Groombridge Ursaa
Majoris), the amount is only 7", and that only in the case
of about a dozen stars does the amount exceed 3". It was
to a fact such as this that Sir J. Herschel alluded in the
paragraph quoted on a previous page, when he spoke of
" motions which require whole centuries to accumulate
before they produce changes of arrangement such as the
naked eye can detect."
Year by year is adding to the number of the observa-
tions, which by their exactitude enable us to detect proofs
of proper motion when those observations are placed in
juxtaposition with observations of the same stars made in
the earlier part of the present century, say between 1800
and 1830. The materials already available seem to point
to the fact that the proper motions of the brighter stars
are, as a rule, greater than those of the fainter stars. The
average proper motions of the ist magnitude stars known
to possess proper motions has been set down at \" annu-
ally, whilst the average displacement of the 6th magni-
tude stars known to be affected amounts to no more
than 5 y.
This law, if law it may be properly called, is subject
to exceptions, for there are some small stars, such as 1830
Groombridge Ursae Majoris, 9352 Lac. Piscis Australis, 61
72 THE STORY OF THE STARS.
Cygni, 21185 Lalande Ursas Majoris, and 21258 Lalande,
which have very considerable proper motions.
The reader who has followed attentively the Trafalgar
Square illustration will have no difficulty in understanding
the statement that a knowledge of a star's proper motion
conveys very little information as to the said star's real
motion reckoned in miles per second. When we say that
a star's proper motion amounts to 4" a year (which is
about 6V in a century), the record is simply that the star's
apparent lateral displacement is so much in such a length
of time along a line assumed to run at right angles to the
observer's line of sight. But the true direction may not
be at right angles as aforesaid ; it may be in a path which
the observer may only see foreshortened. Or, in an ex-
treme case, if the motion takes place directly in the line of
sight so that the star is moving straight towards us, or
from us, it may be in rapid motion and yet visually seem
to have no motion at all ; that is, to be undergoing no
change of apparent place which can be detected by com-
paring observations taken at different times.
Whilst it cannot be said that we know much about the
actual motions of many of the stars, yet we do know
something. The spectroscope furnishes us with some
clue, the basis of which is a principle of physics first enun-
ciated by Doppler in 1842. This principle may be thus
defined : " When the distance between us and a body
which is emitting regular vibrations either of sound or
light is decreasing, then the number of pulsations received
by us in each second is increased, and the length of the
waves is correspondingly diminished." In the case sup-
posed the musical pitch rises, and in the same way the
refrangibiiity of a wave of light which depends upon its
wave length is increased so that it will fall nearer the vio-
let end of the spectrum. A practical illustration of this
principle may often be had by a person standing on the
MOVING STARS. 73
platform of a railway station through which a fast train is
passing at a high rate of speed, whistling continuously as
it passes. It will be noticed in such a case that the pitch
of the whistle continuously varies as the train approaches
the spectator, whilst it goes on continually varying, but in
the opposite direction, after it has passed him and the dis-
tance gradually augments. Whatever was the pitch, say, at
200 yards, before the engine came up to the platform, the
pitch will be the same at 200 yards in the opposite direc-
tion after the engine has passed the platform.
Huggins, in 1868, thought to apply the foregoing prin-
ciple by spectroscopic observations on certain stars with a
view of seeing whether a particular line in a spectrum un-
derwent after an interval any displacement from its nor-
mal position towards either end of the spectrum. If in
any given case there was a displacement towards the red
end of the spectrum, the conclusion would have to be that
the star was receding from the earth : if, on the other
hand, the displacement was towards the violet end of the
spectrum, the conclusion would have to be that the star
was approaching the earth. A general deduction to be
drawn from the observations of Huggins and of others
who have worked in the same field, seems to be that there
are several dozen prominent stars in motion at speeds
varying from 2 to 50 miles a second.
When astronomers once came to recognise the fact
that certain stars were in motion it naturally followed that
there was a desire to ascertain whether any particular
consequences, and if so what consequences, were involved
in the discovery. Sir W. Herschel in 1783 began by try-
ing to classify the proper motions of the stars, so far as
known to him at that epoch. Having done this and find-
ing evident signs that they converged towards a point in
the Constellation Hercules, he was led to conclude that
the Solar System as a whole was moving towards a point
6
74 THE STORY OF THE STARS.
in the Celestial Sphere not far from the star X Herculis.
The principle involved has been thus defined by Professor
Young : " On the whole, the stars appear to drift bodily
in a direction opposite to the sun's real motion. Those in
that quarter of the sky which we are approaching open
out from each other, and those in the rear close up be-
hind us. The motions of the individual stars lie in all
possible directions, but when we deal with them by thou-
sands, the individual is lost in the general, and the pre-
vailing drift appears."
The effect here stated by Young may be seen, and
being seen, may be easily realised, by walking through a
field dotted over with units of any kind, such as sheaves
of corn put up in shocks, or haycocks, or any similar
aggregations of produce. As the pedestrian approaches
a row of such things, the row which at a distance seemed
almost continuous will be found on nearing it to have its
units separated by several feet or yards of distance : as he
passes forwards across the field the first and subsequent
rows will gradually seem to close up behind him into a
more or less compact mass.
Sir W. Herschel's endeavours to find out the " apex "
of the sun's way (as it is called) have been followed up by
other astronomers since, and about 20 different determina-
tions are now available. There is a remarkable general
accord between them all. Perhaps on the whole the
most trustworthy because it is based upon a very large
number of stars is L. Struve's. He has found the point
of convergence to be situated in R. A. i8h. 1301. ; and
Decl. + 27. Huggins, by spectroscopic observations of
an ingenious character, has confirmed the general conclu-
sions thus stated.
A skilful and careful German astronomer, named Mad-
ler, at that time employed at the Observatory of Dorpat
in Russia, put forth, in 1846, an idea that there exists
TEMPORARY STARS. 75
some central point in the universe around which the sun,
with its bevy of planets and comets, revolves in the course
of millions of years ; and he suggested that such centre is
situate in the direction of Alcyone, one of the Pleiades.
It is difficult to pronounce dogmatically for or against
this idea (which, by the way, was rather a revival of a
theory put forth by Wright in 1750 than Madler's own),
but Grant's remarks may be considered to meet the case :
" It is manifest that all such speculations are far in ad-
vance of practical astronomy, and therefore they must be
regarded as premature."
CHAPTER XI.
TEMPORARY STARS.
HISTORIANS of various dates and nationalities tell us
that from time to time stars have blazed forth in the heav-
ens in places where no stars had ever been seen before,
and that after an existence of, it may be, a few weeks or
months, such stars have faded away and been no more
seen. It was at one time considered that the authors of
these statements had been drawing- upon their imagination
for their facts, but the bulk of what has been handed down
to us are well founded. About 12 stars in all are recog-
nised by astronomers under the designation of " temporary
stars." They severally appeared as follows : 134 B. C., 329
A. D., 1572, 1600, 1604, 1670, 1848 (Nova Ophiuchi), 1860
(T Scorpii), 1866 (T Coronas), 1876 (Nova Cygni), 1885
(Nova Andromedas), and 1892 (Nova Aurigas).* The chief
difficulty in regard to all the more ancient cases has been
* Since this chapter was written have appeared : Nova Carinas
and Nova Centauri, 1895 ; Nova Sagittarii, 1898 ; Nova Aquillae,
1899 ; and Nova Persei, 1901. The latter reached almost the bright-
ness of Sirius, February 24, and in some respects was the most re-
markable astronomical phenomena of recent years.
76 THE STORY OF THE STARS.
to determine how far the celestial objects thus recorded to
have burst forth were in any true sense stars, or whether
they were comets or mere meteors. The records which
we have are of very diverse origin, and some of them
2000 years old, handed down to us from times when the
scientific precision and verbal accuracy of modern writing
and speech were unknown. The fact that the ancient
Greeks were a dreamy people, the Romans callous to sci-
ence altogether, and the Chinese " flowery " as nowadays,
renders it extremely difficult for us to sift the wheat from
the chaff, and to prtciser, as the French say, any given
statement. For instance, what is one to make out of the
following Chinese account of something seen in A. D.
173: "On Dec. loth a star appeared between a and /3
Centauri, and remained visible for 7 or 8 months ; it was
like a large bamboo mat (!), and displayed 5 different
colours." Were it not for the fact that on several occa-
sions during the present century new stars have burst
forth, have shone for a while, and have then either disap-
peared absolutely or dwindled almost to invisibility, we
should often have to be sceptical as to the tales told us by
many ancient chroniclers.
Our sources of information are twofold European and
Chinese. The former are generally very vague as to dates
and places ; the latter much more " understandable,"
though both dates and places are often expressed in a
very peculiar fashion. The Chinese observations have
the great merit that they are continuous through many
centuries, and are expressed in language of very uniform
style ; so that once get an insight into the style, and a
European astronomer may feel sure that he can interpret
with tolerable accuracy the entire series, and this is what
has been done. The first workers in this field were cer-
tain French Jesuit missionaries, named Couplet, Gaubil,
and De Mailla, who lived for a while at Pekin some 1 50
TEMPORARY STARS. 77
years ago. They made and brought to France copies of
various Chinese annals, which somehow or other they got
hold of at Pekin. De Mailla's manuscripts were pub-
lished at Paris about 100 years ago, but those of Couplet
and Gaubil still remain, I believe, unpublished. A very
industrious Frenchman named Pingre worked up all these
materials in a book on comets which he published in
1784, whilst another Frenchman named Biot in 1846 gave
to the world a further series of observations. By far the
most complete and accurate, however, of all the existing
versions of the Chinese astronomical records is the late
John Williams's "Observations of Comets from B.C. 611
to A. D. 1640," which appeared in 1871.
All this is a digression from the subject which I wanted
to start with, but it is a digression which seemed neces-
sary under the circumstances of the case.
The earliest " new " star appears to have been one ob-
served by the Greek astronomer Hipparchus, and a tradi-
tion, fathered by Pliny, has always suggested that it was
the appearance of this star which prompted Hipparchus
to compile his, the first catalogue of stars. This tradition
was long regarded as a myth, but as a new star in Scorpio
is recorded by the Chinese to have been seen in 134 B.C.,
a few years before the date commonly assigned to Hippar-
chus's Catalogue, there seems now no sufficient reason for
rejecting the tradition above referred to. Passing over
new stars asserted to have appeared in 945 A. D. and 1264
A. D., the authenticity of which is gravely doubtful (the
accounts probably referring to the great comets of those
years), we come to the year 1 572. In that year there was
a celebrated new star with which Tycho Brahe's name is
often linked, because he left behind him a particularly full
account of it. It was visible for 17 months from Novem-
ber, 1572,10 March, 1574. Brighter than Sirius, it rivalled
Venus. It changed colour from white to yellow and red
78 THE STORY OF THE STARS.
and then back again to white, and remained stationary all
the while that it was visible. D'Arrest pointed out in 1864
that within i' of arc of the place assigned by Argelander
to Tycho's star there exists a small star, which Hind and
Plummer found in 1873 to be certainly variable in its
light. The position for 1890 of Tycho's star is R. A., oh.
1 8m. 405.; Decl. + 63 32'.3. Amateurs possessed of
telescopes, say of 3 inches aperture, might usefully em-
ploy their time in finding and watching this supposed
Tycho star. It follows a certain gth mag. star at a dis-
tance of 2 1. 6s., and is 10' 4" to the S. This 9th mag.
star may itself be identified by reason of the fact that it
follows a star known as Flamsteed's 10 Cassiopeia? (mag.
6) at a distance of ijm. 125., and is 6.4' to the N. of it.
In 1604 and in 1670 temporary stars of considerable
brilliancy became visible. The star of 1604 appeared in
Ophiuchus, and grew to be nearly as bright as Venus,
lasting 12 months or longer. The star of 1670, often
called " Anthelm's star," appeared in Cygnus, and reached
the brightness of a star of the 3rd mag. It lasted alto-
gether about 2 years, but faded away and then bright-
ened up again more than once before its final disap-
pearance.
In April, 1848, a new star of the 5th mag. was seen in
Ophiuchus by Hind. It eventually rose to the 4th mag.,
and then faded away and became very small, but has
never entirely disappeared. This star is now ranked as a
recognised variable, but it seems not to have received
much notice of late years.
In 1866 a very remarkable transformation took place
in the case of a star which had been previously recorded
in 1855 by Argelander as being of the 9th or loth mag.
Birmingham at Tuam, on May 12, 1866, found the star
shining as of the second mag. Combining the testimony
of Birmingham with that of Schmidt of Athens, it would
TEMPORARY STARS. 79
seem that this star brightened up from the 4th to the 2nd
mag. in about 3 hours on the evening of May 12. It
soon began to lose light, and after diminishing to below
mag. 9 it rose to 7$ in September, and remained at that
for the rest of the year. This star also is now treated as
a recognised variable, though we have gained very little
additional knowledge respecting it.
In November, 1876, after several days of pronounced
bad weather, Schmidt at Athens observed on the 24th a
new star of the yd mag., yellow in colour. By the begin-
ning of December it had sunk to the 5th mag., and by the
end of December to the 7th mag., and now it seems to
have disappeared altogether.
In August, 1885, a new star burst out in, or in front of,
the Great Nebula in Andromeda. Though it only reached
the 6th mag., yet, owing to the large number of telescopes
and spectroscopes brought to bear on it, this nova has a
considerable and very interesting history attached to it.
One moral to be drawn from this is that amateur
observers need not fancy that there is no work for
them to do in Astronomy. Respecting this star, I
will here state historically what seems to have hap-
pened. The Great Nebula in Andromeda is one of the
largest and most important of the known nebulas, as we
shall see when we come to speak of that class of celestial
objects. It ordinarily offers the appearance of an exten-
sive and dense oval mass of luminous haze. It so pre-
sented itself to various observers during the first half of
August, 1885. Priority in noticing it to be otherwise
that is, as having a star in or on it seems to rest either
with the late Mr. Isaac Ward, of Belfast, or with a Hun-
garian lady, the Baroness de Podmaniczky, who on
August 22 had staying with her at her husband's house
a professional astronomer, Dr. De Kovesligethy. There
was a telescope of 3$- inches aperture in the house.
8o THE STORY OF THE STARS.
Hostess and guest several times made use of this
telescope, and on August 22 the baroness remarked to
the doctor that she saw a little star in the nebula, a state-
ment which the visitor confirmed. Yet the phenomenon
was so faint that both believed the full moon was the in-
direct cause, the moonlight overshadowing the fainter
portions of the nebula, and permitting only of the visibil-
ity of the bright centre. It was not till more than a week
after the above date that the existence of the new star
was generally recognised, though there is evidence to
show that some days previously to August 22 the nebula
as a nebula had exhibited unwonted brightness. To none,
however, of the observers who noted this fact does it
appear that the thought presented itself that they were
gazing on a stellar object. At its brightest this new star
seems to have reached the 6th magnitude, and there is
reason to suppose that when Mr. Ward and the Baroness
de Podmaniczky saw the star it was rising to, but had not
reached, its maximum brilliancy. The date of this may
perhaps be put at August 31. The star then rapidly de-
clined in lustre until the end of September, when it stood
at about the loth magnitude. It then further diminished
until it became merged in the nebula itself, or rather until
its luminosity became lost in the luminosity of the nebula.
An interesting question arose as to what were the rela-
tions, if any, between the new star and the nebula. A
very competent French astronomer named Trouvelot sug-
gested the following reasons for concluding that there
was no physical connection between the star and the neb-
ula. There are a multitude of small stars visually scat-
tered all over the nebula. Trouvelot considers these to
belong to the Milky Way, of which he traces an extension
beyond the nebula, since they increase in number as the
Milky Way is approached. They are likewise perfectly
sharp and well-defined, which they would not be if they
TEMPORARY STARS. 8 1
were either in the nebula or behind it. He concludes,
therefore, that the nebula lies behind the Milky Way.
The well-defined appearance of the new star, and of a
small star near it, which he thought was also a new one,
seemed to prove that they were both in front of the nebula,
and were associated with the Milky Way rather than with
the nebula. These surmises, it will be observed, throw
no light upon the question why this new star should sud-
denly have blazed forth and as suddenly have faded away.
I must, however, add my testimony to Trouvelot's so far
as to say that when I saw the new star myself on Sep-
tember 3, in a 6-inch refractor, I could not refrain from
entering in my note-book the thought that " the star had
nothing to do with the nebula."
On December 13, 1885, Mr. J. E. Gore in Ireland no-
ticed a new star of the 6th magnitude, reddish in colour,
situated some 20' following % l Orionis. It was found to
have a beautiful banded spectrum of Secchi's Type III.
Six months later it had diminished to below the I2th mag-
nitude. It afterwards increased again, and is now recog-
nised as a variable going through all its changes of mag-
nitude in about 12 months. Why the sudden and special
increase of its light in December, 1885, cannot be sur-
mised.
There yet remains another new or temporary star for
mention, the history of which is extremely interesting. On
February r, 1892, an anonymous postcard was received by
Dr. Copeland, the director of the Royal Observatory at
Edinburgh, to the effect that a new star of about the 5th
magnitude had become visible in the constellation Auriga
not far from the star ^. It subsequently transpired that
the postcard had emanated from a certain Dr. Anderson,
an amateur living in Edinburgh, who had discovered the
star by the joint use of a small pocket telescope and Mc-
Clure's edition of Klein's " Star Atlas." The history of
82 THE STORY OF THE STARS.
this star during the weeks immediately preceding its dis-
covery by Dr. Anderson became known in a very curious
way. Professor Pickering of Harvard College, U. S., had
recently conceived the idea of " patrolling the heavens "
every fine night by means of a small photographic transit
instrument which would automatically sweep the meridian
in a series of steps of sufficient exposure to photograph
6th magnitude stars, at intervals corresponding to the
equatorial breadth of the field. The scheme was well
adapted for the detection of strange objects brighter than
6th magnitude stars, and so it resulted that Anderson's
star was found on 1 3 photographs taken between Decem-
ber 10, 1891, and January 20, 1892. As it appeared on
all these, which embraced stars down to the 9th magni-
tude, but was not to be found on the photograph of De-
cember 8th, the presumption is that the new star bright-
ened up from below the 9th magnitude between December
8th and December loth. After remaining at about the
4th or 5th magnitude till the end of February, it dimin-
ished somewhat rapidly in brightness, and by the end of
March had fallen to below the I2th magnitude. Observa-
tions were continued at the Lick Observatory in California
till April 26th, when bad weather supervened. It was
then of the i6th magnitude, so that it may be said to have
practically disappeared. In August, however, it had
brightened up again to above the loth magnitude, finally
subsiding to about the I2th magnitude.
I have dwelt somewhat fully on the so-called "tem-
porary " stars, because the subject is one which seems to
open up opportunities of scientific usefulness to the class
of persons under whose notice this volume is likely to fall
amateurs possessed of small telescopes, or with no tele-
scopes at all, but with many open-air opportunities of
becoming familiar with the aspect of the heavens.
It may have been inferred from various remarks made
VARIABLE STARS. 83
in this chapter that temporary stars, and variable stars,
which will form the subject of the next chapter, are so
closely associated as almost to imply that all temporary
stars are merely variables of long and irregular periods.
There is much to support this idea, as also the correlative
idea that many of the -"missing" stars are also variables
not yet recognised to be such. But Kirkwood, an ex-
perienced and thoughtful American observer, considers
that the theory that temporary stars are long-period vari-
ables is unsound : that the suddenness of their apparition,
the short duration of their maximum brightness, and the
great length of their periods, if they are really periodic, are
reasons for regarding them as distinct in their nature from
the variable stars properly so-called. It is worthy of
notice that there is no known instance of a new star
appearing and remaining permanently visible.
CHAPTER XII.
VARIABLE STARS.
A LISTLESS observer of the stars will regard them as
always preserving their brilliancy, be it much or little, un-
changed, but such is not the case with all of them ; a cer-
tain number vary from time to time in their light, and are
therefore called " variable " stars. The number of those
of which it may be said with certainty that they undergo
periodical changes of brilliancy amounts to nearly 300 ;
but it is probable that as many again may be regarded as
possibly subject to fluctuations of light. In the absence
of absolute standards for comparison, the systematic study
of variable stars is a matter involving much patience on
the part of the observer and much refinement in his pro-
cedure. Were the number of observers endowed with
84 THE STORY OF THE STARS.
the requisite patience and experience much increased,
there is no doubt that large additions would soon be made
to our lists of variable stars. This department of astrono-
my is entirely modern, for the ancients have left us merely
a few vague statements of stars having disappeared, and
we can seldom determine with adequate precision the
places occupied by them.
Professor Young has made some remarks on the
method of observation to be resorted to in the case of
variable stars, which it may be useful to quote here. He
says : " There is no better way than that of comparing
the star by the eye, or with the help of an opera-glass,
with surrounding stars of about the same brightness at
the time when its light is near the maximum or minimum ;
noting to which of them it is just equal at that moment,
and also those which are a shade brighter or fainter. It
is possible for an amateur to do really valuable work in
this way, by putting himself in relation with some ob-
servatory which is interested in the subject. The observa-
tions themselves require so much time that it is difficult
for the working force in a regular observatory to attend
to the matter properly, and outside assistance is heartily
welcomed in gathering the needed facts. The observa-
tions themselves are not specially difficult, require no
very great labour or mathematical skill in their reduc-
tion, and, as has been said, can be made without instru-
ments ; but they require patience, assiduity, and a keen
eye."
One of the most celebrated of the periodical stars is
o Ceti, otherwise known as Mira (the " wonderful " star),
which latter name has been given to it precisely because
it undergoes such remarkable changes. Its period is
33id. 8h. ; that is to say, it goes through its changes 12
times in about 1 1 years. At its maximum brightness it
sometimes rises to the 2nd mag., remaining thereat for
VARIABLE STARS. 85
about a fortnight; it then diminishes during about 3
months, becomes invisible except in large telescopes for 5
months, and finally requires another 3 months to regain
its pristine maximum brilliancy. These may be taken as
average intervals, but it does not always diminish or increase
by the same gradations ; its maximum brightness is not
always the same, nor are the intervals of time between
maximum and maximum always identical. These irregu-
larities were studied very carefully by Argelander, who
came to the conclusion that the period of 33 id. of Mira
itself varies in about 88 of such periods, with the result
that the single periods gradually lengthen and shorten
alternately to the extent of 25 days one way or the other.
Moreover, it is not improbable that the irregularities in
the star's maximum brilliancy are also periodical, and that
at every nth maximum the star attains to a greater de-
gree of brilliancy than its usual maximum brilliancy.
This supposition would explain the fact that whilst the
naked-eye visibility of Mira generally extends to about 18
weeks, it was in 1859-60 so observed during 21 weeks,
whilst in 1868 the term was but 12 weeks. It was in this
year that Heis noted the maximum magnitude to be only
the 5th, whilst in 1888 it attained to about the 3rd mag.,
and therefore of course remained a naked-eye object for
a much longer period. The discovery of the variability of
this star dates back as far as 1596. On August 13 of that
year David Fabricius noted a certain star in Cetus to be
of the 3rd magnitude. In the following October he failed
to find it. In 1603 Bayer, in preparing his " Star Atlas,"
assigned the Greek letter o to a star in Cetus occupying
the spot where Fabricius's star had disappeared. He
noted it to be of the 4th mag., but being either ignorant
of, or neglectful of, the earlier observations of Fabricius,
he lost the chance of being able to claim the honour of
discovering the star's variability. The spectrum of Mira
86 THE STORY OF THE STARS.
is a remarkable one of Secchi's Illrd Type, in which
bright lines have been seen.
Perhaps Algol (/3 Persei) may be regarded as, after
Mira Ceti, the second most remarkable variable in the
heavens, or, at any rate, in the Northern hemisphere, as it
is second also in point of date of discovery. The fact of
its variability was noticed by Montanari in 1669, was con-
firmed by Maraldi in 1694, and investigated half a century
later by a Saxon farmer named Palitzch, celebrated for his
early detection of Halley's Comet in 1758. But it was
Goodricke, in 1782, who first determined in full detail the
changes of brilliancy which Algol undergoes. It com-
monly shines as a star of mag. 2j ; from that it descends
to about 3|. Pickering, from photometric measures at
Harvard College, finds that the star's light diminishes
during 4-h. 23m. before minimum. When the minimum
is reached, then 5h. 37m. pass before the star regains its
normal maximum. It remains at this for about 2d. loh.
The most rapid changes take place during about 100
minutes before and 100 minutes after the epoch of mini-
mum. Pickering suggests that the range of variability is
less than is commonly stated, and does not exceed one
whole magnitude. The period in which the entire series
of changes take place is about 2d. 2oh. 48m., and is
thought by Chandler to have diminished by 8s. since
Goodricke's time ; but to talk about 8s. in such a connec-
tion is a refinement of precision which savours of affec-
tation.
Another naked-eye variable handy, by reason of its
position and magnitude, for observers in the Northern
hemisphere is 8 Cephei. Its period is 5d. 8h. 47m. count-
ing from minimum to minimum, and its range from about
mag. 3f to mag. 4|. The interval between maximum and
maximum is not equally divided by the minimum phase,
for it takes longer for the star to pass from its maxi-
VARIABLE STARS. 87
mum to its minimum than it does to regain its maximum
after a minimum. The former transformation occupies
3d. I ph. but the latter only id. I4h. The variability of
8 Cephei was discovered by Goodricke in 1784, and the
whole period is put at sd. 8h. 48m.
Tj Aquilae and /3 Lyras may also be mentioned as short-
period variables, which on that account, and because they
are visible to the naked eye, are specially suitable for ob-
servation by amateurs in England.
rj Aquilae varies from about mag. 3$ to mag. 4f in a
period of about jd. 4h. I4m., but this period itself seems
variable. The star is yellow in colour and yields a spec-
trum of Secchi's Ilnd Type.
/3 Lyrae is remarkable as having a double maximum
and a double minimum, which together make up a main
period of I2d. 2ih. 47m. The variations take the follow-
ing form : Starting from a maximum when the star is of
mag. 3^, it descends to its first minimum of mag. 4 ; it
then rises to the same maximum as before, but in descend-
ing to the next minimum it goes down to mag. 4^. Arge-
lander ascertained that /3 Lyrae resembles Mira Ceti as
regards the circumstances of its period in other words,
that its period is itself variable; that down to 1840 the
period was increasing, but that after 1840 it began to de-
crease, and was decreasing at the time when Argelander
made this remark in 1866. Pickering has propounded the
idea that this star is a " surface of revolution " or a sphe-
roid in form and differently luminous in different parts,
and that the epoch of minimum light represents a time
when the darker portion at one of the ends is presented
to the earth. This seems to be one of those far-fetched
fancies which can neither be proved nor disproved. The
variability of /3 Lyrae was discovered by Goodricke in
1784.
I have reserved to the last that which is perhaps the
88 THE STORY OF THE STARS.
most remarkable, as certainly it is the most erratic, of all
the prominent variable stars r) Argus. Unfortunately it
is not visible in the Northern hemisphere. Halley, on his
return from St. Helena, as far back as 1677, frequently ex-
pressed doubts as to the constancy of the light of the stars
in Argo. Though he seems only to have based his conclu-
sions upon Ptolemy's statements of star magnitudes, yet
these were generally so accurate that when discrepancies
were found to exist between modern and ancient records
the idea at once suggested itself that there had been actual
change rather than mistakes of observation. Halley, in
1677, rated ij Argus as of the 4th magnitude. In 1751
La Caille noted it as of the 2nd magnitude. In the next
half century it diminished, for Burchell, during his resi-
dence and travels in South Africa, between 1811 and
1815, saw it as of the 4th magnitude. Fallows, in 1822,
at the Cape, and SirT. M. Brisbane, between 1822 and
1826, in New South Wales, saw it as of the 2nd magni-
tude. In the following year, that is, on Feb. i, 1827,
Burchell, then at St. Paul's, in Brazil, saw it as of the ist
magnitude, and almost as bright as a Crucis ; but within
a year, that is, by Feb. 20, 1828, it had decreased to the
2nd magnitude, and as such was entered by M. J. John-
son and Taylor in their respective catalogues between
1829 and 1833. Sir John Herschel, who started observa-
tions at the Cape in 1834, found it then and for several
years afterwards to be something between mags, i and 2
but nearer 2. It seems to have remained stationary, or
nearly so, for well-nigh 3 years, but on December 16,
1837, on resuming work after an interval, Sir John was
startled to find it had become one of the very brightest
stars of the ist magnitude, excelling all belonging to that
category except Sirius and Canopus. Sir John Herschel's
account of it will bear quoting : " Its light was nearly
tripled. ... It very decidedly surpassed Procyon, which
VARIABLE STARS. 89
was about the same altitude, and was far superior to AI-
debaran. It exceeded a Orionis, and the only star (Sirius
and Canopus excepted) which could at all be compared
with it was Rigel, which it somewhat surpassed. From
this time its light continued to increase. On December
28 it was far superior to Rigel and could only be com-
pared with a Centauri, which it equalled, having the ad-
vantage of altitude, but fell somewhat short of it as the
altitudes approached equality. The maximum of bright-
ness seems to have, been obtained [attained] about Janu-
ary 2, 1838, on which night both stars being high and the
sky clear and pure, it was judged to be very nearly
matched indeed with a Centauri, sometimes the one,
sometimes the other, being judged brighter, but on the
whole a was considered to have some little superiority.
After this the light began to fade." Sir John then goes on
to narrate the incidents of the declension of the star's light.
His own observations ceased in April, 1838, but the star
even then remained bright enough to be compared with Al-
debaran. From other sources we learn that the diminu-
tion of light went on for 5 years, but that even in March,
1843, the star's lustre continued equal to that of an ordi-
nary i st magnitude star. At about that time a new outburst
took place, and according to the observations of Mackey at
Calcutta, and Maclear at the Cape, 77 Argus surpassed
Canopus and scarcely fell short of Sirius in brilliancy.
This lasted more or less through 1844, when a decline in
its brilliancy set in. This proceeded, however, very slow-
ly, because in February, 1850, Lieut. Gilliss, then in Chili,
reported 17 Argus as being nearly as bright as Canopus
but of a reddish-yellow colour, somewhat darker than
Mars. In 1856 it was still of the ist mag., but a steady
decline was evidently in progress. Hence we find that in
1858 it was rated at mag. 2^ by Powell ; in 1860 at mag.
3 by Tebbutt; in 1861 at mag. 4J by Abbott; in 1863 at
7
90 THE STORY OF THE STARS.
mag. 5 by Ellery; in 1867 at mag. 6 by Tebbutt. Dur-
ing the next 10 years it fell to mag. 7, and in March, 1886,
was rated at mag. 7^ by Finlay at the Cape of Good Hope.
This appears to have been the lowest point, for by May,
1888, the light had increased by fully half a magnitude,
so that apparently it is on its way towards another maxi-
mum, which perhaps may be expected within the first dec-
ade of the 2oth century. From the foregoing account it
is, however, clear that we do not possess sufficient infor-
mation to assign with any reasonable degree of accuracy
a period to TJ Argus, though Wolf has suggested 46 years,
and Loomis 67 years. Schonfeld, however, thinks that
the star has no regular period at all. At any rate the
maximum stage seems very complicated and to consist of
3 maxima which jointly occupy 25 years of the period
whatever that may be. During this sub-period, the
changes may perhaps be regarded as restricted to the ist
and 2nd magnitudes, and this sub-period may perhaps be
assumed to fall something like in the mid-interval between
every 6th or 7th magnitude minimum of the star.
17 Argus is in the field with the celebrated "Great
Nebula in Argo," and some remarkable circumstances
bearing alike on the star and on the nebula will come
under consideration in a later chapter in which the nebula
will be described.
The reader who has followed me thus far in trying to
pick up some ideas about the peculiarities of the stars
called " variable " will very likely wish now to put the
question, "What is a variable star?" It is impossible to
answer such an inquiry with any confidence. It seems,
however, likely that the variability of the stars which are
known to be variable may be due to one of two causes,
one of which applies to one class of star and the other to
another class. It is generally accepted by astronomers
that Algol is a type of a small number of stars which owe
VARIABLE STARS. 91
their peculiarity to a cause quite different from that which
applies to the vast majority of these objects. The idea
was started by Pigott in 1783, and has met with much
acceptance, that the periodical fluctuations in the light of
Algol are due to the revolution round it of an opaque
satellite smaller than itself yet large enough to eclipse
partially the primary. With respect to the general run of
variables it is thought that we may draw some inferences
respecting them from what we know of the physical con-
stitution of the sun and of what happens in or upon that
luminary. Now we know that from time to time, and ac-
cording to a period which is recognised to amount to
about 1 1 years, dark spots of various sizes and shapes and
of different depths of shade break out upon the sun. The
solar spots which we are accustomed to see, even the very
largest of them, are too small relatively to the size and
brilliancy of the sun to cause any measurable depreciation
in the aggregate of the sun's light, but let us suppose it
were otherwise, and that every 1 1 years masses of spots
so extensive as to represent one-half or even one-fourth of
the apparent surface of the sun, burst forth, we should
then have the great centre of our system converted from
a permanently bright star into a variable star. I speak of
our sun as a bright star because probably it represents for
us on the earth neither less nor more than what Sirius or
other bright stars * represent to the inhabitants of other
worlds in far-off regions of space. If we could travel from
the earth a long way towards Sirius we should probably
find Sirius to grow into what we should without reserva-
tion call a sun, whilst our sun would deteriorate into what
we now call a star.
So much for the possible circumstances of those stars
which undergo periodic changes of light. But this expla-
* See p. 58 (ante).
92 THE STORY OF THE STARS.
nation, even if accepted so far, does not meet the case of
those temporary outbursts of stellar light which we con-
sidered in Chapter XI. (ante). Here again, however, solar
history may be brought in. It is now quite recognised as
a fact that the red flames seen during total eclipses of the
sun are outbursts of glowing hydrogen gas emanating
from the interior of the sun ; nay, more, that such emana-
tions of burning hydrogen are constantly occurring on the
sun. Now in the case of the temporary star in Corona
Borealis which became visible in 1866, Huggins's observa-
tions tended to show that there happened in that star a
sudden and extraordinary outburst of glowing hydrogen,
which by its own light, as well perhaps as by heating up
the whole surface of the star, caused the unwonted in-
crease in its brilliancy which then took place. These
ideas find confirmation in other directions, but it seems
hardly within the design of this work to go further into
details of this character.
There are, however, some miscellaneous facts con-
nected with variable stars which are too interesting to be
passed over. For instance, it is an undoubted fact that
the vast majority of the variable stars are red or reddish
in colour ; and so general is this rule that whenever a new
star is found it is a safe presumption to start with that if
its colour is red it has hitherto escaped observation be-
cause of its being variable. Hind has noticed that vari-
able stars when at minimum often appear hazy or foggy, on
which Arago suggested the idea that the diminution of
brilliancy might be due to the interference of clouds. It
is an undoubted fact that in the case of red variable stars
as they diminish in brilliancy they deepen in colour, whilst
as their light increases their hue becomes paler.
An experienced American observer, Chandler, has
evolved a connection between the colours and periods of
variable stars. He not only subscribes to the opinion
VARIABLE STARS. 93
that variable stars are generally red, but he finds that the
more red they are the longer their periods. Of 1 1 2 vari-
ables whose colours and periods are fairly well estab-
lished, classifying them in groups having periods of under
i oo days, of 100 days but under 200, and so on up to
over 400, he finds that whilst of those under 100 days
barely one-half are red, of those over 100 days three-
fourths are red ; whilst those over 400 days are all red.
His statistics arranged in another form show that whilst
the periods of the white and yellow stars average 125
days, the periods of the red stars average 288 days, and of
the intense red 477 days.
Espin has arrived at some curious statistics concern-
ing the distribution of variable stars in the heavens, and
also concerning their periods. He finds that they are
especially numerous in a zone of the heavens inclined 1 5
or 20 to the equator ; that this zone crosses the preced-
ing side of the Milky Way on the N. side of the equator,
and the following side of the Milky Way on the S. side of
the equator ; that the northern portion of the zone is not
many degrees broad and is clearly marked, but that the
southern portion is split into 2 streams of stars and that
the place where this occurs is near the place where the
Milky Way is also divided ; that hereabouts the variables
seem connected with the Milky Way, often occurring in
the gaps and constantly on the edges of the gaps, but
rarely in the centre of the star sprays from the Milky
Way ; whilst the northern stream of variable stars is
sharply defined by itself and seems unconuected with the
Milky Way. Espin adds that with one or two exceptions
all the temporary stars have appeared in the region where
the Milky Way and the variable star zone are both
broken into two streams ; and that stars which do not
belong to the above-named zone are chiefly the bright
and short-period variables. Espin's statistics in detail
94 THE STORY OF THE STARS.
are too elaborate for embodiment in these pages in their
entirety, but some further general conclusions are of
sufficient interest and importance to be reproduced.
Writing in 1882 he found that the variables then known
readily fell into two classes : (i) those with periods of
less than 70 days ; and (2) those with periods of more
than 135 days ; there being none with periods between 71
and 135 days. Of the former group it might be said
that they were in colour white or red in tolerably even
numbers, and large in magnitude ; whilst the latter group
were mainly red and small in magnitude.
Some other conclusions which he arrived at were that
if the variation of. light be small in extent, or if the star be
bright, the period will probably be short ; on the other
hand, where the period ranges from 135 days up to 420
days the number of stars increases with the length of the
period ; also, that between a range of i magnitude up to
6 magnitudes the number of stars increases with the vari-
ation in magnitude. These rules seem, however, to fail
where the stars have periods of more than 420 days, or
where the range extends beyond 6 magnitudes.
The foregoing statistics are based upon only a minority
of the known variables, and therefore cannot yet be put
forward as disclosing a series of general laws. Neverthe-
less, they are sufficiently interesting and pronounced to de-
serve attention now, as well as to encourage further in-
quiry in the future.
The following classification of variable stars has met
with some acceptance in America, and therefore it may be
given here, but it is open to the objection that it assumes
that temporary stars are merely long-period variables,
which at present is, at the best, an assumption :
(1) Stars showing slow continuous change.
(2) Stars exhibiting irregular fluctuations of light : al-
THE STARS IN POETRY. 95
ternately brightening up and becoming dim with-
out any apparent law.
(3) Temporary stars, which blaze out suddenly and
then disappear.
(4) Periodic stars of the type of o Ceti, usually of long
period.
(5) Periodic stars of the type of /3 Lyrae, of short
period.
(6) Periodic stars of the type of Algol, in which the
variation of light is such as would result from
some intervening body eclipsing the primary
star.
It is evident from all that has gone before that variable
stars form a very interesting branch of observational as-
tronomy.
CHAPTER XIII.
THE STARS IN POETRY.
As the previous chapter concludes what I have to say
respecting the stars taken individually, and the remainder
of this volume will be occupied with the stars in masses
under the designations Clusters and Nebulae, the present
seems a convenient point at which to withdraw the reader's
thoughts for a while from the technicalities of science to
things more light and sentimental. Hence it has occurred
to me to try and enliven my pages by a few citations from
English classical poetry a field which has been worked
with great assiduity, from an astronomer's standpoint, by
Mr. J. E. Gore.*
Shakespeare of course occupies the front rank amongst
the great English writers who have brought the facts of
* In his Scenery of the Heavens.
96 THE STORY OF THE STARS.
science, astronomical and general, into line with their or-
dinary musings. Unfortunately he lived at a period when
the so-called science of astrology flourished side by side
with astronomy, and trading as it did on the credulity of
man it overshadowed but too successfully the sister science
of astronomy, if such a bracketing together of fraud and
humbug with true learning can be tolerated. Perhaps,
after all, we of the igth century must not be too hard on
our forefathers of the Elizabethan epoch, for figures of
speech implying a belief in the tenets of astrology and in
many other ridiculous beliefs and practices hold sway in
these closing years of the century, and they are not re-
stricted to ignorant and unlettered dwellers in remote
agricultural villages.
And now to Shakespeare. In Julius Ccesar (Act i.,
scene 2) Cassius says
" Men at some times are masters of their fates ;
The fault, dear Brutus, is not in our stars
But in ourselves, that we are underlings."
The idea that the stars exercise some influence, for weal
or woe, over the birth of individuals was widely prevalent
300 years ago, and Shakespeare does no more than con-
form to the ideas of the times when he makes Richard III.
say (Act iv., scene 4)
' ' Lo, at their births good stars were opposite ; "
or Jupiter, in Cymbeline, say (Act v., scene 4)
" Our Jovial star reign'd at his birth ; "
whilst Romeo (Act v., scene 3) speaks in the Churchyard
scene of shaking
" The yoke of inauspicious stars."
THE STARS IN POETRY. 97
Malvolio, in Twelfth Night (Act ii., scene 5), expresses
the popular sentiment in words most clear
" In my stars I am above thee ; but be not afraid of great-
ness ; "
and then follow immediately the familiar sentiments
" Some are born great, some achieve greatness, and some have
greatness thrust upon them."
Particular constellations or groups of stars are occa-
sionally referred to by Shakespeare. Thus in Othello
(Act ii., scene i) the sea, stirred by the wind, is said to
" Seem to cast water on the burning Bear,
And quench the Guards of the ever-fixed Pole."
What idea underlies the application of the term " burning "
to Ursa Major does not appear.
The Pole Star receives elaborate treatment in Julius
Casar (Act iii., scene i). Cassar himself thus speaks
" But I am constant as the northern star,
Of whose true-fix'd and resting quality
There is no fellow in the firmament.
The skies are painted with unnumber'd sparks,
They are all fire, and every one doth shine ;
But there's but one in all doth hold his place."
In the letter read by Polonius {Hamlet, Act ii., scene 2)
we come upon an idea which is alike ancient (for Stoics
and Epicureans held it) and modern
" Doubt thou the stars are fire :
Doubt that the sun doth move."
Milton is another of our great national writers who
makes various allusions to celestial objects. In the Para,
dise Lost (Book vii.) he refers to the moon and stars
98 THE STORY OF THE STARS.
"... then formed the moon
Globose, and every magnitude of stars,
And sowed with stars the heavens, thick as a field ; "
and to the Pleiades (in the same book)
"... the gray
Dawn, and the Pleiades, before him danced,
Shedding sweet influence."
Young's Night Thoughts is peculiarly rich in its ref-
erences to astronomy. Perhaps the best-known passage
of all is that in the " gth Night," which runs as follows :
'' Devotion ! Daughter of Astronomy,
An undevout Astronomer is mad.
True ; All Things speak a God ; but in the Small
Men trace out Him ; in Great He seizes Man."
In the following passage (" 8th Night ") we come upon
the idea already mentioned in these pages as being a sober
astronomical probability
" These sparks of night, these stars shall shine,
Unnumber'd Suns."
Again, the following passage referring to the distances of
the stars contains, as we have seen, true astronomical
teaching
" How distant some of these nocturnal Suns !
So distant (says the Sage) 'twere not absurd
To doubt, if Beams set out at Nature's Birth,
Are yet arrived at this so foreign World
Tho' nothing half so rapid as their Flight."
Truly indeed may it be said that the stars serve the pur-
pose thus suggested by Young
THE STARS IN POETRY. 99
" One Sun by Day, by Night ten thousand shine
And light us deep into the Deity."
In Byron's Childe Harold's Pilgrimage (Canto III.,
v. Ixxxviii.) we find the following striking passage :
"Ye stars ! which are the poetry of heaven !
If in your bright leaves we would read the fate
Of men and empires 'tis to be forgiven
That in our aspirations to be great,
Our destinies o'erleap their mortal state
And claim a kindred with you ; for ye are
A beauty and a mystery, and create
In us such love and reverence from afar,
That fortune, fame, power, life, have named themselves a
star."
Shelley in his Prometheus Unbound (Act iv.), speak-
ing of an astronomer in his observatory, says
" Heaven's utmost deep
Gives up her stars, and like a flock of sheep
They pass before his eye, are number'd, and roll on."
Moore in his Light of the Haram thus brings in the
Pole Star
" Whose light, among so many lights,
Was like that star, on starry nights
The seaman singles from the sky,
To steer his bark for ever by ! "
Elsewhere (Sacred Songs) he makes a further allusion to
the Pole Star
"As still to the star of its worship, though clouded,
The needle points faithfully o'er the dim sea."
100 THE STORY OF THE STARS.
By the way, this allusion is not scientifically accurate,
for the compass-needle does not point to the Pole Star,
but to the earth's magnetic pole.
The stars naturally find a place in Thomson's Seasons.
He says
" Snatch me to heaven ; thy rolling wonders there,
World beyond world, in infinite extent,
Profusely scatter'd o'er the blue immense,
Show me : their motions, periods, and their laws,
Give me to scan."
Longfellow remarks
" Wondrous truths, and manifold as wondrous,
God hath written in those stars above."
Wordsworth, in The Excursion (Book IV.) thus
brings in the uses of the Pole Star
" Chaldean shepherds, ranging trackless fields,
Beneath the concave of unclouded skies
Spread like a sea, in boundless solitude
Looked on the polar star, as on a guide
And guardian of their course, that never closed
His steadfast eye."
And in Poems of the Imagination (Part II., xxv.)
" The stars are mansions built by Nature's hand
And, haply, there the spirits of the blest
Dwell clothed in radiance, their immortal vest."
Tennyson is very astronomical. In The Princess we
find
"And the shining daffodil dies, and the Charioteer
And starry Gemini hang like glorious crowns
Over Orion's grave low down in the west."
GROUPS OF STARS. 101
Tennyson has a very good conception of a binary star
when he speaks of
" those double stars
Whereof the one more bright
Is circled by the other."
CHAPTER XIV.
GROUPS OF STARS.
THE thing to do in order to be able to realise to the
utmost the marvellous beauty of the starry heavens, is to
obtain an opportunity of gazing at some of those crowded
fields of stars bordering on the Milky Way, in which the
stars are so close together that though they hardly consti-
tute a " cluster " technically so-called, are yet so numer-
ous that the whole circular field of the telescope is one
shining mass of bright points. There is such a field,
favourably circumstanced for observers in England in the
constellation Perseus (R. A. 2h. iim. 203. Decl. + 56 38'),
and I would urge every reader of this book to take the
first opportunity open to him of viewing this in a telescope
of, -if possible, not less than 3 inches aperture. Doing
this he will, I am confident, be more inspired to dedicate
to astronomy some of his time, thoughts, and money, than
by doing anything else which I could suggest. This par-
ticular object is sometimes called " The Cluster in the
Sword Handle of Perseus."
Starting with the stars as single stars we have seen
that a considerable number go together in pairs; that a
smaller number are associated in triplets ; and so on, till
we come to a principal star having, it may be, half a dozen
companions gathered round it. The transition from such
102 THE STORY OF THE STARS.
a group to what is called a "cluster," and so on to a "re-
solvable nebula," is a gradual one which, however, may
be said to come about in the nature of things almost as a
matter of course. The lines of demarcation between
these different classes of objects are naturally not very
pronounced, and must be laid down in a rather arbitrary
manner. However, I think that for our present purpose
we may conveniently range the celestial objects now
about to be described under the three following heads :
(1) Irregular groups more or less visible to the naked eye ;
(2) Clusters of stars resolvable into their constituent stars,
with the aid of a telescope ; (3) Nebulae for the most part
irresolvable with the telescopes we at present possess ;
either because the telescopes are deficient in the neces-
sary optical power, or because the objects themselves are
not stellar at all, but are something else gaseous or what
not.
Of the groups of stars which may be considered to be
incipient clusters there are several visible to the naked
eye, not counting certain true nebula? which can be de-
tected by the naked eye by reason of their great size.
Three of these clusters were noticed and recorded by the
ancients, namely, the " Pleiades " and " Hyades " in Tau-
rus, and " Praesepe " in Cancer. The Pleiades are men-
tioned twice in the Book of Job, and once in the prophecy
of Amos, and also in Homer, who likewise names the
Hyades. The passages in Job and Amos have already
been quoted.* The passage in Homer (Odyssey Lib. v.
ver. 270) runs thus in Pope's version :
" With beating heart Ulysses spreads his sails ;
Plac'd at the helm he sat, and mark'd the skies,
Nor clos'd in sleep his ever-watchful eyes.
* Ante, p. 40.
GROUPS OF STARS. 103
There view'd the Pleiads, and the northern team,
And great Orion's more refulgent beam,
To which, around the axle of the sky
The bear revolving, points his golden eye."
The Pleiades were always supposed to be 7 in num-
ber; then one was said to have disappeared, so that 6
only remained. This transaction appears to be lost in
obscurity ; I had even said is unhistoric. Yet Ovid has
recorded it in the famous line :
" Quse Septem dici, sex tamen esse solent."
However, whilst ordinary eyes can, as a rule, only grasp
6 stars, the 7th is still there, and can be seen with the
slightest optical help ; whilst very good eyes can make out
several more. Miss Airy, indeed, has noted 12. With a
small telescope any number (say at least 50) may be seen,
and photography has recorded over 2000 stars. The
brightest in the group is Alcyone, otherwise rj Tauri, of
the 3rd magnitude ; next in order come Electra and Atlas,
both 3!, Maia 4, Merope 4^, Taygeta 4^ ; whilst Celeno,
Asterope, and Pleione are all smaller and of much the
same brightness, say mag. 6. Then follows a miscellane-
ous crowd of smaller stars.
A passing allusion must be made to certain modern
discoveries connected with the Pleiades, the exact import
of which is at present very imperfectly understood. On
October 19, 1859, Tempel, a German observer resident in
Italy, observed an object which he took to be a telescopic
comet. On the following evening he found it in the same
position, and therefore not a moving comet, but a station-
ary nebula. It was seen subsequently by other observers.
Auwers noted it to be about i in extent, but thought
that it might have escaped notice owing to its proximity to
Merope, one of the Pleiades, the bright light of which
104 THE STORY OF THE STARS.
would overshadow the nebula. Schiaparelli in 1875 saw
the nebula very clearly, and was much surprised at its
FIG. 12. The Pleiades.
size and apparent ramifications in different directions,
Hind had stated that he had often suspected nebulosity
around some of the smaller outlying stars of the Pleiades.
The earlier observations of this nebula (or these nebulas)
GROUPS OF STARS. 105
in the Pleiades were by no means very consistent, and the
idea of variability suggested itself ; some even regarded
the whole thing as a myth. But later researches by the
aid of photography have not only established the reality
of Tempel's discovery, but have done a good deal more ;
for it is now certain that no fewer than five of the chief
stars in the Pleiades (Pleione, Atlas, Asterope, and Tay-
geta being the exceptions) are involved in a mass of nebu-
lous matter, the extent of which was never suspected
until the photographic proof was obtained at Paris in
1885. It is satisfactory, under the circumstances, to know
that a general confirmation of the photograph has been
obtained by the direct testimony of the telescope in the
shape of eye-views at the Russian observatory at Pul-
kowa, with the gigantic refractor of 30 inches aperture
there in use.
The Hyades form a more open and less interesting
group, also in the constellation Taurus, and near Alde-
baran; but the stars are too scattered to make a very
striking field.
Praesepe in Cancer is altogether a more effective group ;
one, however, which should be looked at through a tele-
scope with a low power and large field. This object, long
called the " Bee-hive," appears to have been the first ob-
ject to which the term " nebula " was applied in bygone
days, its component stars not being separately distinguish-
able. We have it on record that Prassepe was taken
account of by the ancients 2000 years ago ; for both
Aratus and Theophrastus tell us that its dimness and dis-
appearance during the progressive condensation of the
atmosphere were regarded as the first sign of approaching
rain. Galileo with his baby telescope counted 36 stars.
To find Prassepe, carry an imaginary line from Spica
Virginis under Regulus in Leo, and about 22 beyond it
will strike Prassepe.
106 THE STORY OF THE STARS.
The group of stars forming the constellation Coma
Berenices is cited by Webb as " a gathering of small stars
which obviously at a sufficient distance would become a
nebula to the naked eye." By the way, this constellation
is said to have been instituted by the astronomer Conon
in honour of the Queen of Ptolemy Soter, who dedicated
her splendid tresses to the gods to secure her husband's
safety in war !
CHAPTER XV.
CLUSTERS OF STARS.
WE have now to consider the clusters of stars which,
though seemingly nebulous in very small telescopes, be-
come immediately resolved into individual stars on the
application of a very slight additional amount of optical
power. A select number of these are put together in the
Appendix for the use of those readers of this book who,
possessing telescopes, would wish to know whither to
direct them profitably. It will suffice, therefore, to allude
here to only a few of these clusters. 31 ip VI. Cassiopeiae
is a somewhat conspicuous object and readily seen with a
telescope of 2 inches aperture. Perhaps the best known
of all the so-called globular clusters is 13 M. Herculis, that
is to say, the I3th in Messier 's Catalogue and in the con-
stellation Hercules. This is commonly regarded as the
finest of the globular clusters. Smyth called it " an ex-
tensive and magnificent mass of stars with the most com-
pressed part densely compacted and wedged together
under unknown laws of aggregation." Sir J. Herschel
spoke of its thousands of stars and " hairy-looking curvi-
linear branches," which features the Earl of Rosse inter-
preted as indicative of a spiral tendency ; he also perceived
CLUSTERS OF STARS. 107
several dark rifts in the cluster. Beautiful as it is one
might even say magnificent yet J. P. Nichol goes a little
too far in asserting that " perhaps no one ever saw it for
the first time through a telescope without uttering a shout
of wonder."
Before offering any further remarks on the larger clus-
ters it will be convenient to explain the word "globular,"
FIG. 13. 13 M. Herculis.
and seemly to say something about the French astrono-
mer Messier, whose name is so closely associated with
these objects. "Globular," as a word, of course needs
no explanation, but it was first applied to star clusters, I
believe, by Sir W. Herschel, in order to convey to the
mind the idea that, when looking at them, the eye is gaz-
ing not on a flat background sprinkled with stars, but on
a veritable ball of stars. Without saying that all or even
any of the clusters so called are truly such, yet undoubt-
edly an ordinary eye will readily appreciate them as balls
of stars.
108 THE STORY OF THE STARS.
Messier was a Frenchman who dedicated himself about
a century ago to the task of hunting for comets. In car-
rying out this work he was so far very successful that be-
tween 1760 and 1798 he found no fewer than 13. He
was, however, much bothered by constantly coming upon
objects in his small telescope which, whilst they looked at
first like comets, were only clusters and nebulae ; so in
1758 he thought to guard against being taken in any more
by forming a permanent catalogue of nebulas, including
clusters, by collecting together all that had been found by
himself, La Caille, and Mechain. This catalogue was
published (but whether for the first time or not I am not
sure) in 1784, and is alike a monument of its author's
shrewdness and of his industry, for it embraces, with
scarcely an exception, the whole of the conspicuous clus-
ters and nebulas visible in the latitude of Paris.
We will now resume our consideration of the clusters
by mentioning a few more of them. Next after the clus-
ter in Hercules comes perhaps 5 M. Libras, which, in the
words of Webb, is a " beautiful assemblage of minute
stars greatly compressed in the centre." Sir W. Herschel
with his 4O-ft. reflector made out about 200 stars, though
the middle of it was so compressed that it was impossible
to individualise the components. Smyth says that :
"This superb object is a noble mass, refreshing to the
senses after searching for faint objects, with outliers in all
directions and a bright central blaze." Messier, however,
" assured himself that it did not contain a single star,"
but this unsound statement was the unwise result of dog-
matising, on the strength of a telescope 2 feet long.
80 M. Scorpii is a compressed globular cluster which
Messier, who found it in 1780, described as resembling
the nucleus of a comet ; and indeed its blazing centre and
attenuated disc give it a very cometary aspect. Sir W.
Herschel pronounced it to be the richest and most con-
CLUSTERS OF STARS. 109
densed mass of stars which the firmament can offer to
the contemplation of astronomers, albeit that Messier had
FIG. 14. 5 M. Librae.
registered it as Ntbuleuse sans Jtozles. Near the centre of
this object, or, as Webb suggested, " between it and us,"
there burst forth in 1860 a remarkable temporary star.
Pogson had been familiar with the cluster because two
variable stars, R and S Scorpii, were in the field with it,
and he had frequently been in the habit of viewing them.
On May 28, 1 860, while seeking for these variables, his at-
tention was arrested by the fact that a star of about the
7th magnitude had appeared in the place previously occu-
pied by the cluster. He had seen the cluster as recently
as May 9, and was positive that it had appeared exactly the
same as usual without anything stellar about it. The
same instrument and power had been employed on both
occasions. A fortnight later, that is, on June 10, using a
lower power, the stellar appearance had nearly vanished,
but the cluster still shone with unusual brilliancy and a
110 THE STORY OF THE STARS.
marked central condensation. Pogson's observations were
fully confirmed by two German observers, E. Luther and
Auwers. Pogson thus summed up the circumstances of
this curious case : " It is therefore incontestably proved
upon the evidence of 3 witnesses that between May 9 and
June 10 [1860] the cluster known as 80 Messier changed
apparently from a pale cometary-looking object to a well-
defined star fully of the yth magnitude, and then returned
to its usual and original appearance. It seems to me ab-
surd to attribute this phenomena to actual change in the
FIG. 15. 80 M. Scorpii.
cluster itself, but it is very strange if a new variable star,
the 3rd in the same field of view, should be situated be-
tween us and the centre of the cluster." At the time
when this was written the incident thus narrated was
unique, but the more recent case of Nova Andromedas ap-
pears to present various analogies to the case of 80 M.
Scorpii in 1860. Schonfeld thought he saw some trace of
the star in June, 1869, but, barring this, I am not aware of
any further information being on record. There are many
CLUSTERS OF STARS. in
other globular clusters to be met with in the heavens,
some which will be found referred to in the List in the
Appendix, but 2 more only need be mentioned here.
These are both in the southern hemisphere, and surpass,
it would seem in the matter of size and brilliancy, anything
visible in England.
47 Toucani was described by Sir J. Herschel as a su-
perb globular cluster " very visible to the naked eye and
one of the finest objects in the heavens. It consists of a
very condensed spherical mass of stars of a pale rose-
colour concentrically enclosed in a much less condensed
globe of white ones 15' or 20' in diameter." Herschel, in
speaking of this cluster, made the very curious and sig-
nificant remark that he could not remember a single ellip-
tical nebula which is resolvable, all the resolvable clusters
being more or less circular in form. He then goes on to
add : " Between these two characters then (ellipticity of
form and difficulty of resolution) there undoubtedly exists
some physical connection ... it deserves also to be no-
ticed that in very elliptic nebulas which have a spherical
centre (as in 65 M.) a resolvable or mottled character of-
ten distinguishes the central portion, while the branches
exhibit nothing of the kind." This was written prior to
the construction of Lord Rosse's great telescope, and
therefore it is no reflection on Sir John's accuracy to point
out that the " Crab Nebula " in Taurus is an exception to
the above rule.
Respecting the cluster surrounding 03 Centauri, Sir John
Herschel says that " it is visible to the naked eye as a dim,
round, cometic object about equal to a star of 4^ magni-
tude, though probably if concentrated in a single point the
impression on the eye would be much greater. Viewed
in a powerful telescope it appears as a globe of fully 20'
in diameter, very gradually increasing in brightness to the
centre, and composed of innumerable stars of the I3th
112 THE STORY OF THE STARS.
and 1 5th magnitudes, the former probably being two or
more of the latter closely juxtaposed."
This chapter may appropriately be concluded with a
mention of some large clusters not specifically globular in
form. 67 M. Cancri is a rich but loose cluster at the root
of the Crab's southern claw. Smyth noted it as consist-
ing principally of a mass of stars of the pth and loth mag-
nitudes, gathered somewhat in the form of a Phrygian
FIG. 1 6. 67 M. CancrL
cap, followed by a crescent of stragglers. W. Herschel
saw above 200 stars at once in the field of view. This ob-
ject precedes a Cancri by about 2.
77 M. Ceti is a round stellar object near f in the con-
stellation named. It is small, bright, and exactly on a
line with 3 small stars, one preceding and 2 following ; of
which the nearest and largest is of the pth magnitude.
CLUSTERS OF STARS.
Sir W. Herschel made this object a peg on which to hang
the following remark : " We may conclude that the pro-
fundity of the nearest part is at least of the 9ioth order."
By this Sir William meant that this object is 910 times as
S
FIG. 17. 77 M. Ccti (nebulous star).
far off as stars of the first magnitude ; but, to say the
least of it, this is a highly imaginative thought one of a
type which I think is too common and rather apt to
make astronomy and astronomers look ridiculous in the
minds of matter-of-fact people.
The cluster u M. AntinoT is an interesting cluster of
uncommon form. Smyth likened it to a flight of wild
ducks, a simile more appropriate than many of those met
with in astronomical writings. There is an 8th magni-
tude star in the middle, and two outside its limits and
preceding it. Smyth remarks : " By all analogy these
are decidedly between us and the cluster." This, how-
114 THE STORY OF THE STARS.
ever was not the opinion of Kirch, its discoverer, who, in
1 68 1, described it as a small, obscure spot, with a star
shining through and rendering it more luminous.
In the field with, and adjacent to, the star K Crucis
there is a large and loose cluster, described by Sir John
Herschel as one of the most beautiful objects of its class.
It comprises more than 100 stars from the yth magnitude
downwards, 8 of the more conspicuous of them being
coloured various shades of red, green, and blue. This
object was very carefully surveyed in 1872 by Russell at
Sydney, who remarked that many of the stars had drifted
(presumably in consequence of proper motion) in the 40
years which had elapsed since Sir John's drawing was
made. Russell adds : " The colours of this cluster are
very beautiful, and fully justify Herschel's remark that it
looks like a ' superb piece of fancy jewellery.' "
CHAPTER XVI.
NEBULA.
IN the present chapter we shall consider the Nebulas
commonly so called those celestial objects of very diverse
sizes, shapes, and brilliancy, of which many or most are
probably stellar in their constitution, though some of
them, however, may be not such but gaseous. At the
outset I will deal with them merely descriptively. Mes-
sier's catalogue, to which such frequent allusions have
been made, embracing as it did only those larger and
brighter objects which were within reach of a mere hand
telescope, does in no way indicate the present state of our
knowledge respecting the nebulae. The bulk of the ob-
jects enrolled by Messier eventually proved to be resolvable
star clusters, though a residue were veritable nebulae^
NEBULA. 115
faint, misty objects, many of them not unlike specks of
luminous fog. Of these nebulae some have yielded to the
larger telescopes of modem days, and have proved to be
masses of stars too closely aggregated together to be re-
solved by the puny telescopes which only were available a
century or more ago. Since Messier's days, and as a re-
sult of so many large telescopes having been set to work
during the second half of the nineteenth century, the num-
ber of observed nebulas has become so great that upwards
of 8000 are now on record. By far the greater number of
these are, however, irresolvable, and therefore it is an
open question what they are.
The nebulae generally may be conveniently classified
under six general heads, it being understood of course
that this classification only has regard to form or size :
(i) Annular nebulas; (2) elliptic nebulas ; (3) spiral nebu-
las ; (4) planetary nebulae ; (5) nebulous stars ; (6) large
nebulas of irregular form.
The annular nebulas hitherto recognised scarcely num-
ber a dozen, and of these one only is large or bright
enough to have obtained much notoriety. This is Mes-
sier's 57th in the constellation Lyra. If it be realised that
the word " annular " is derived from the Latin word an-
nulus, a ring, a ready clue will be had as to the general
form of these bodies. The annexed engraving indicates
it, but only that simple conception which is obtainable by
means of a moderate-sized telescope say an instrument
of 4 inches aperture. With instruments of much larger
size the individuality of the ring disappears, and the cen-
tral space, black or nearly so in a small telescope, shows
evident indications of nebulous matter, which Lord Rosse
found to be distributed, not uniformly, but in streaks ;
whilst the external edge of the ring was broken by pro-
jections of various sizes and shapes. All these particulars
will be better understood from a picture than from any
116 THE STORY OF THE STARS.
written description. There is considerable conflict of
opinion as to the ultimate account which ought to be ren-
dered of this object when the largest available telescopes
FIG. 18. The ring nebula in FIG. 19. The ring nebula in
Lyra. (SirJ.Herschel.) Lyra. (Earl o
are brought to bear upon it ; Rosse, Chacornac, and
Secchi all claimed to have resolved it into stars. Hug-
gins, on the other hand, insists that it is merely a mass of
glowing gas. The Lick observers find its structure to be
very complex, but seem unwilling to commit themselves
to a very definite opinion on the subject. At the same
time they make mention of the existence of, and describe
the position of, numerous individual stars.
Elliptic nebulas of various degrees of eccentricity, from
a common oval to a long streak, are met with in various
parts of the heavens. As a rule they are very bright, and
several of them are remarkable as having double stars at
or near each of their foci. There is one elliptic nebula
which stands out beyond all the rest, yet its great size,
brilliancy, and peculiar features forbid its being regarded
as a typical elliptic nebulae. I am here alluding to the
" Great Nebulae in Andromeda," Messier's 3ist. Its ellip-
ticity is considerable ; it is likewise very long, and has a
bright central condensation which renders it readily dis-
NEBULAE. 117
coverable by the naked eye on a clear night not far from
the star rj Andromeda of magnitude. 4$-. Sir John Her-
schel's drawing is well known, having obtained wide cir-
culation through his own and other people's books. G.
P. Bond was the first to improve upon it, which he did
when he published, more than 40 years ago, an engraving
exhibiting much more internal detail than Herschel had
shown. In particular two curious black streaks or longi-
tudinal vacuities, which run nearly parallel to the major
axis of the oval on the south side. Bond traced the neb-
ula to a length of 4 and a breadth of 2^.
Roberts (see Frontispiece) has carried the matter still
further than Bond had done, for he finds traces of a dark
ring separating the central parts of the nebula from an
outer brighter portion, the whole yield-
ing traces of what may indicate a
spiral structure. No telescope has
yet resolved this object distinctly into
stars, though several hundred stars
have been counted within its limits.
This object is, however, probably
stellar, and may one day be proved to
be such; certain is it that it is not FIG. 20. The neb-
gaseous. The other extreme of ellip- ^ is 43 # L vir '
tic nebula is illustrated in Fig. 20,
which represents 43 jp I. Virginis, a long, narrow wisp
of luminous matter with a slight condensation in the
centre.
" Spiral," or, as they are sometimes called, " Whirl-
pool " nebulae first had that special feature of them brought
out by the late Earl of Rosse. The best known is Mes-
sier's 5 1st in the constellation Canes Venatici. To Sir J.
Herschel it presented the appearance of a bright globular
cluster encompassed at some distance by a bright nebu-
lous ring, which varied very much in brightness in its
n8
THE STORY OF THE STARS.
different parts. It seemed as if it was split through for
about fths of its circumference into 2 laminae, one of
which gave the impression that it was turned up towards
the eye, out of the general plane. Sir John saw, seem-
FIG. 21. The spiral nebula 51 M. Canum Venaticorum.
(SirJ. Herschel.)
tngly detached from the main object, a small, bright,
round nebula. Lord Rosse's telescope entirely altered
the aspect of the whole group. The ring was found to
pass into a distinct spiral coil of nebulous matter, and the
outlying portion to be connected with the main mass by
NEBULA.
a curved band, the whole showing indications of resolvabil-
ity into stars. No ordinary telescope affords even suspicion
of these details. The spectrum appears to be non-gaseous.
" Planetary " nebulae are objects first so designated by
Sir W. Herschel because they exhibited a fairly well defined
outline as of a disc, circular or slightly oval. The most
FIG. 22. The spiral nebula 51 M. Canum Venaticorum. (Earl o/Rosse.)
striking of these is Messier's p7th in Ursa Major, 2 south
and following the star /3. It has been described as " a
very singular object, circular and uniform, and after a long
inspection looks like a condensed mass of attenuated light."
It has a diameter of 2' 40". The late Earl of Rosse de-
tected perforations and a spiral tendency in it. He found
120 THE STORY OF THE STARS.
a star in about the centre of each main perforation and
called it the " Owl " nebula, from its appearance. One of
the stars seems to have disap-
peared since 1850, or, as a
thoughtful writer suggests, the
owl has closed one of his eyes !
Huggins has found the spec-
trum gaseous.
The planetary nebulas are
not very numerous and not very
bright, which is a matter for re-
gret, because it would seem that
FlG< 23 i7ura jypalor.' nebula thev possess interesting features
entitling them to the special at-
tention of astronomers but needing large telescopes. For
instance, there is one in the constellation Draco, No.
37 in Sir W. Herschel's IVth class, which, according
to Professor Holden, who has studied it with the Lick
telescope, possesses an extraordinary structure. He says
that it " is apparently composed of rings overlying each
other, and it is difficult to resist the conviction that these
are arranged in space in the form of a true helix." At
the first glance the nebula appears to Holden to consist
of 2 circles which intersect, a central star being within
the area, resulting from the intersection of the 2 circles.
At the S. point of intersection the brightness is ap-
proximately twice the average brightness of the circum-
ference ; at the N. point it is less bright relatively. A
little attention, however, seems to show that these rings
are so arranged that one complete ring lies on the upper
or hither side (nearer the eye) of the other complete ring
which is undermost or farther from the eye. There is
another peculiar feature. The nebula itself is unmistak-
ably blue in colour, whilst the star is yellowish-red. Star
and nebula yield different spectra, and require for accu-
NEBULA. 121
rate definition the telescope to be brought to a different
focus according as it is desired to obtain a good image
of the one or the other. All these facts point to remark-
able intrinsic peculiarities in this object. Holden finds
the nebula I ip IV. Aquarii to possess some analogies
with the nebula in Draco just described.
Before passing away from the planetary nebulas some
further peculiarities appertaining to them deserve a pass-
ing notice. According to the spectroscope, they are most-
ly gaseous, and several are noticeably bluish in hue.
Three-fourths of them are in the southern hemisphere,
and the greater number are in, or very close to, the Milky
Way.
" Nebulous stars," according to their name, are ordi-
nary stars with a faint nebulosity surrounding them ; but
the term does not seem altogether a happy one. Hind
remarks that the nebulosity is in some cases well defined,
but in other cases is quite the reverse ; that " the stars
thus attended have nothing in their appearance to dis-
tinguish them from others entirely destitute of such ap-
pendages ; nor does the nebulous matter in which they
are situated offer the slightest indication of resolvability
into stars with any telescopes hitherto constructed."
Perhaps the most striking nebulous star is No. 45 in
Sir W. Herschel's IVth class, in the constellation Gemini.
Sir John Herschel speaks of it as an 8th magnitude star
which lies "exactly in the centre of an exactly round,
bright atmosphere 25" in diameter." Key described it as
" a bright but somewhat nebulous star closely surrounded
by a dark ring ; this again by a luminous ring ; then an
interval much less luminous, and, finally, at some distance
an exterior luminous ring." This description accords well
with the late Earl of Rosse's.
The brightest nebulous star certainly recognised as
such appears to be i Orionis, a triple star of mag. 3^.
9
122 THE STORY OF THE STARS.
f Orionis, of mag. i\, is often spoken of as a star sur-
rounded by a nebulosity, but the evidence is very contra-
dictory, and inclines on the whole to the negative.
The last class of nebulae remaining to be described
are some of very diverse size and shape, which cannot be
brought under any general denomination.
The " Crab nebula " in Taurus bears a popular and
familiar designation, but it does not seem to rest on a
very satisfactory foundation. In all ordinary telescopes
this object exhibits a simple oval outline, but the special
title was based on the late Lord Rosse's early description
of it, which Sir John Herschel thought justified by the
facts, though the later Parsonstown observations seem to
negative the claw features. It was the discovery of this
object in 1758, when he was following a comet, which led
Messier to form his well-known catalogue of nebulae.
All things considered, it seems probable that the
" Great Nebula in Orion " must be regarded as the
grandest and most interesting of all the nebulae. I have
in a previous chapter mentioned it in connection with the
multiple star 6 Orionis, which it surrounds ; and the dia-
gram already given, rough though it is, affords an idea of
the prominent feature of the nebula which presents itself
in every small telescope, namely, the " Fish's mouth."
Sir John Herschel's general description, written a great
many years ago, still in the main holds good, though
modern observations, when 'made with the large tele-
scopes of the present day, bring out many features not
recognised half a century ago ; and in particular exhibit
very distinctly what may be called the flocculent charac-
ter or structure of the nebula.
Sir John Herschel's account runs as follows : " In its
more prominent details may be traced some slight resem-
blance to the wings of a bird. In the brightest portion
are four conspicuous stars, forming a trapezium. The
NEBULAE. 123
nebulosity in the immediate vicinity of these stars is floc-
culent and of a greenish-white tinge ; about half a degree
northward of the trapezium are 2 stars involved in a
branching nebula of singular form, and southward is the
star t Orionis, also situated in a nebula. Careful exam-
ination with powerful telescopes has traced out a contU
nuity of nebulous light between the great nebula and both
these objects, and there can be but little doubt that the
nebulous region extends northwards as far as in e the belt
of Orion, which is involved in a strong nebulosity, as well
as several smaller stars in the immediate neighbourhood."
Secchi thought that this nebula must be considered as
extending far beyond the limits usually assigned to it, and
that there exist in various directions, and remote from the
principal centre, scattered fragments of nebulous matter
which all really belong to the main mass. He ascribed to
the whole, speaking roughly, a triangular outline with a
base of 4 and a height of about 5J, reaching downwards
from in Apex (with a break, however, at <r) almost as
far as . Photographic and spectroscopic observations
have been carried out on a considerable scale of late years.
The latter are thought to indicate that the nebula consists
of incandescent hydrogen gas. The multiplication of pho-
tographs spread over a term of years may lead to a better
understanding of the circumstances and conditions of this
nebula than is at present possible. The existing drawings
of it, extending over nearly a century, are so much want-
ing in consistency one with another as to have led many
persons to surmise that it has undergone distinct change,
but the evidence to support this theory falls far short of
what is necessary to sustain such a suggestion.
30 Doradus is a nebula in the Southern hemisphere
which, from Sir John Herschel's description and engraving
of it, must be a very remarkable object. Sir John speaks
of it as " one of the most singular and extraordinary ob-
124 THE STORY OF THE STARS.
jects which the heavens present." Strange to say, he
does not describe it in detail, contenting himself by saying
that the engraving (in his Outlines of Astronomy) is so
satisfactory as to render further description superfluous.
The special feature of this nebula is the wonderful series
of convolutions which it exhibits masses of nebulous
matter twisted in and out in singular fashion with num-
berless black, or more or less starless, interstices.
Another Southern nebula not entirely unlike the fore-
going is that surrounding the strange variable star j Ar-
gus already described. Sir John Herschel's account of it,
penned at the Cape of Good Hope some 60 years ago,
runs as follows: "Viewed with an 1 8-inch reflector, no
part of this strange object shows any sign of resolution
into stars, nor in the brightest and most condensed por-
tion, adjacent to the singular oval vacancy in the middle
of the figure, is there any of that curdled appearance, or
that tendency to break up into bright knots with interven-
ing darker portions, which characterise the nebula of
Orion, and indicate its resolvability. ... It is not easy for
language to convey a full impression of the beauty and
sublimity of the spectacle which this nebula offers, as it
enters the field of the telescope (fixed in R. A.) by the
diurnal motion, ushered in as it is by so glorious and in-
numerable a procession of stars, to which it forms a sort
of climax."
Some mystery hangs over this nebula and its central
star. Much excitement was caused in 1863 by the publi-
cation of an announcement by Abbott, of Hobart Town,
Tasmania, that, whereas Sir John Herschel had noticed
near the centre of the nebula a lenticular sort of space de-
void of stars, ?; being some distance from this void and
closely encompassed by nebulous matter, the void space
had altered in form, and the star (which had dwindled
down to the 6th mag.) no longer had nebulous matter
NEBULA. 125
close up to it. These assertions, indicative, if true, of ma-
terial changes in the appearance of the nebulas having
taken place between 1883 and 1863, were reviewed by
Captain J. Herschel, in India, and Dr. B. A. Gould, in
South America, and others, and the general verdict was
that the allegations of Abbott were unfounded, and that
Sir John Herschel's drawing of 1833 continued in 1882 to
represent the details of the nebula as they were to be seen
at the later date.
The constellation Sagittarius contains 2 large nebulous
masses of considerable interest at no great distance from
each other. 20 M. Sagittarii is the chief member of an
important group respecting which Sir John Herschel
writes as follows : " One of them is singularly trifid, con-
sisting of 3 bright and irregularly formed nebulous masses,
graduating away insensibly externally, but coming up to a
great intensity of light at their anterior edges, where they
enclose and surround a sort of three-forked rift or vacant
area, abruptly and uncouthly crooked, and quite void of
nebulous light. A beautiful triple star is situated precisely
on the edge of one of these nebulous masses, just where
the interior vacancy forks out into two channels."
8 M. Sagittarii, not far from the last named, is another
remarkable object, perceptible to the naked eye, and show-
ing effectively, even in a telescope as small as a 3-inch.
Sir John Herschel thus speaks of it : " A collection of
nebulous folds and masses, surrounding and including a
number of oval dark vacancies, and in one place coming
up to so great a degree of brightness as to offer the ap-
pearance of an elongated nucleus. Superposed upon this
nebula, and extending in one direction beyond its area, is
a fine and rich cluster of scattered stars, which seem to
have no connection with it as the nebula does not, as in
the region of Orion, show any tendency to congregate
about the stars."
126 THE STORY OF THE STARS.
The small constellation Scutum Sobieskii contains a
rather famous object sometimes (but not very judiciously)
FIG. 24. The " Omega" nebula in Scutum Sobieskii.
called the " Horse-shoe " nebula, or by others (and with
more propriety) the " Omega " nebula. From the engrav-
ing annexed it will be seen that, as regards at any rate a
small telescope, the idea conveyed is more that of a swan
as seen floating on the surface of water. As in the case
of 77 Argus, allegations have been made, and apparently
with better foundation in this case, that important changes
have taken place in the appearance of this nebula since the
first drawings of it were made. Weighty names are at-
tached to these conclusions, and Holden, who has investi-
gated with much care and detail its history, as recorded
between 1833 and 1875, concludes that " the ' Horse-shoe '
has moved with reference to the stars," and that therefore
" we have evidences of a change going on in the nebula.
This may be a veritable change in the structure of the neb-
ula itself, such as was suspected by Schroter, confirmed
by O. Stuve, and again confirmed by myself in the nebula
NEBULA. 127
of Orion ; or it may be the bodily shifting of the whole
nebula in space."
The " Dumb-bell " Nebula (27 M. Vulpeculae) is too
well known to need a lengthened description in this place.
The records of its appearance during more than a century
past, as telescopes of successively increasing power have
been brought to bear on it, constitute a weighty warn-
ing to those who, on the strength of seeming discrepancies
in verbal descriptions and drawings, choose to infer that
absolute changes have taken place in the appearance or
circumstances of celestial objects. It is not too much to
say that whilst the designation " Dumb-bell " is fairly ap-
propriate in describing this object as seen in telescopes
up to 6 or 8 or more inches of aperture, yet this feature
becomes inappreciable altogether in the giant telescopes
of the present day, which run to 20, or 30, or 40 inches of
aperture. Roberts's photograph of this object is visually
almost irreconcilable with the older drawings, in which
the " Dumb-bell " idea is the dominant one.
The Southern hemisphere contains two objects which
must not be passed over in treating of nebulas. These
are the " Magellanic Clouds," or the " Nubecula Major "
and " Nubecula Minor " both of them terms recalling the
cloudlike appearance of these objects, the words " major "
and " minor " relating of course to their size. Both are
at no great distance from the Pole, the " Greater Cloud "
being in the constellation Dorado, and the " Lesser
Cloud " in Toucan. They are of a somewhat oval shape
and visible to the naked eye, but the smaller one disap-
pears in strong moonlight. Sir John Herschel describes
them as consisting of swarms of stars, clusters, and
nebulae.
The distribution of the nebulae in the heavens is a sub-
ject which has attracted the attention of many astrono-
mers who have had theories to advance respecting such
128 THE STORY OF THE STARS.
topics, or who have written on the constitution of the
Universe. But I do not know that it can be said that
very much light has been thrown upon the questions of
this character which have presented themselves for solu-
tion. One thing is very noteworthy, and no doubt is sig-
nificant, but we do not know of what it is significant. The
distribution of the nebulae over the heavens is extremely
unequal. They congregate in a zone which crosses the
Milky Way at right angles. The majority are to be
found in a zone which scarcely embraces an eighth part
t of the heavens. The constellation Virgo is where they
are gathered together in greatest number, and they abound
also in the neighbouring constellations of Leo, Ursa
Major, Camelopardus, Draco, Bootes, Coma Berenices,
and Canes Venatici. In the part of the heavens almost
exactly opposite to these constellations that is to say, in
Pegasus, Andromeda, and Pisces they are also numer-
ous. The inequality in the distribution of the nebulae
will perhaps be best brought home to the reader by con-
sidering how they are distributed in hours of Right As-
cension. Of the 5079 clusters and nebulas entered in Sir
John Herschel's Catalogue of 1864 whilst the XlXth and
XXth hours contain only 79 and 90 objects respectively,
the Xlth hour contains 421 and the Xllth 686. The
last-named hour is that which embraces a large part of
Virgo. The regions of the heavens which lie nearest to
the Milky Way are the poorest in nebulae, while they
are most abundant around the Poles of that great and
mysterious belt. In the Southern hemisphere the nebulas
are more uniformly spread over the zone which surrounds
the South Pole. On the other hand, their aggregate num-
ber is smaller; nevertheless there are 2 magnificent re-
gions there which alone contain nearly 400 nebulae and
star clusters.
It is a remarkable fact that almost all the nebulae in-
THE MILKY WAY. 129
dicated by the spectroscope to be gaseous are situated
either within the Milky Way or closely adjacent thereto ;
whilst in the regions near the poles of the Milky Way
gaseous nebulae are wanting, though other nebulas are
abundant.
The reader will remember what has already been said
respecting the alleged variability of great nebula in Orion,
of the nebula surrounding rj Argus, and of the " Omega "
nebula in Vulpecula. Subject to the remarks already
made in dealing with those 3 nebulas, it is to be consid-
ered that, though there are such things as variable stars,
no variable nebulas are known to exist.
CHAPTER XVII.
THE MILKY WAY.
THOUGH when one gazes at the Milky Way there is,
in a certain sense, not much to see (or at least not much
which one can realise), yet an attentive consideration of it
with the assistance of a telescope brings to light a vast
variety of details of the highest interest. How it pre-
sented itself to our English forefathers is sufficiently
shown by Milton's well-known description of it (Paradise
Lost, bk. vii. v. 577-81) as
" A broad and ample road, whose dust is gold
And pavement stars, as stars to thee appear,
Seen in the Galaxy, that Milky Way
Which nightly, as a circling zone, thou seest,
Powdered with stars."
From the foregoing it will appear that Wordsworth
was not displaying his own original genius when (in Dion)
he spoke of
130 THE STORY OF THE STARS.
" Heaven's broad causeway paved with stars."
Perhaps before I recount any further speculations of
this character we had better consider the Milky Way de-
scriptively. So far as I know the only astronomer who
has written on it, and been able to do so from personal
study of it in both hemispheres of the earth, is Sir John
Herschel. It is obvious that no description of such an
object can be adequately framed merely by the colloca-
tion of accounts prepared piecemeal, but that there is re-
quired the pen of a man who has taken notes of it at first
hand round its entire circumference. I make no apology,
therefore, for borrowing, in a simplified and condensed
form, Sir John Herschel's description of the Milky Way.
Following the line of its greatest brightness, as well as
its varying breadth permits, its course conforms as nearly
as may be to that of a great circle inclined about 63 to
the equinoctial, and cutting that circle in R. A. 6h. 47m.,
and i8h. 47m., so that its poles are in R. A. I2h. 47m.,
Decl. N. 27 and R.A. oh. 47., Decl. S. 27. Through-
out the region where it is sub -divided this great circle
runs as it were in between the 2 great streams of galaxy
matter, with a nearer approximation, however, to the
brighter and continuous stream. If we trace the Milky
Way in the order of R. A., we find it traversing Cassi-
opeia, its brighter part passing about 2 to the North of
8. Passing thence between y and e it sends off a branch,
southwards and preceding, towards a Persei, conspicuous
as far as that star, prolonged faintly towards e Persei, and
possibly traceable towards the Hyades and Pleiades. The
main stream, however (which is here very faint), passes
on through Auriga over t, (, rj, preceding Capella, between
the feet of Gemini and the horns of Taurus (where it in-
tersects the ecliptic nearly in the solstitial colure), and
thence over the club of Orion to the neck of Monoceros,
THE MILKY WAY. 131
intersecting the equinoctial in R.A. 6h. 54m. Up to this
point, from the offshoot in Perseus, its light is feeble, but
thenceforward it gradually brightens up, and from the
shoulder of Monoceros and over the head of Canis Major
it presents a broad, moderately bright, very uniform and,
to the naked eye, starless stream up to the point where it
enters the prow of Argo nearly on the Southern Tropic.
Here it again subdivides (about the star m Puppis), send-
ing off a narrow and winding branch on the preceding
side as far as y Argus, where it abruptly terminates.
The main stream pursues its southward course to the
33rd parallel of South Declination, where it diffuses itself
broadly and again subdivides, opening out into a wide
fan-like expanse, nearly 20 in breadth, formed of inter-
lacing branches, all of which terminate abruptly, in a line
drawn nearly through X and y Argus.
Here the continuity of the Milky Way is interrupted
by a wide gap, and where it recommences on the oppo-
site side it is by a somewhat similar fan-shaped assem-
blage of branches which converge upon rj Argus. Thence
it crosses the hind feet of the Centaur, forming a curious
and sharply defined semicircular cavity, and enters the
Cross by a bright isthmus not more than 3 or 4 wide
this is the narrowest portion of the Milky Way. After
this it immediately expands into a bright mass, enclosing
a and $ Crucis and Centauri, extending almost up to
a Centauri. In the midst of this bright mass, and occu-
pying about ^ its breadth, occurs a singular dark pear-
shaped vacancy about 8 long and 5 broad, very con-
spicuous, and for several centuries past called the " Coal-
sack " a name given to it by the early navigators. In
this vacancy there is only one very small naked-eye star,
though there are telescopic stars. The striking blackness
is the effect of contrast with mass of bright matter by
which the black area is surrounded. This is the place of
132 THE STORY OF THE STARS.
the nearest approach of the Milky Way to the South
Pole. Throughout all this region its brightness is very
striking, and when compared with the more Northern
portion, the course of which has been already traced, con-
veys strongly the idea of greater proximity, and would
almost lead to a belief that our situation as spectators is
separated on all sides by a considerable interval from the
dense body of stars composing the Galaxy, which in this
view would have to be considered as a flat ring of im-
mense and irregular breadth and thickness within which
we are eccentrically situated, nearer to the Southern than
to the Northern part of its circuit.
At a Centauri the Milky Way again subdivides, send-
ing off a great branch of nearly half its breadth, but
which thins off rapidly, at an angle of 20 with its gen-
eral direction, towards the preceding side to ij and d Lupi,
beyond which it loses itself in a narrow and faint stream-
let. The main stream passes on, increasing in breadth,
to y Normae, where it makes an abrupt elbow and again
subdivides into one principal and continuous stream of
very irregular breadth and brightness on the following
side, and a complicated system of interlaced streaks and
masses on the preceding, which covers the tail of Scorpio,
and terminates in a vast and faint effusion over the whole
extensive region occupied by the preceding leg of Ophiu-
chus, extending northwards to a parallel of 1 3 of South
Declination, beyond which it cannot be traced, a wide in-
terval of 14 free from all appearance of nebulous light
separating it from the great branch on the North side of
the equinoctial of which it is usually represented as a con-
tinuation.
Returning to the point of separation of this great
branch from the main stream at a Centauri, let us now
pursue the course of the latter. Making an abrupt bend
to the following side it passes over t Aras, 6 and i Scorpii,
THE MILKY WAY.
133
and y Telescopii to y Sagittarii, where it suddenly collects
into a vivid oval mass about 6 in length and 4 in breadth,
so excessively rich in stars that a very moderate calcula-
tion makes their number exceed 100,000. Northward of
this mass this stream crosses the ecliptic in longitude
about 276, and proceeding along the bow of Sagittarius
into Antinoiis, has its course rippled by 3 deep concavi-
ties separated from each other by remarkable protuber-
ances, of which the larger and brighter (situated between
the stars 3 and 6 Aquilae) forms the most conspicuous
patch in the Southern portion of the Milky Way visible in
English latitudes.
Crossing the equinoctial at the XlXth hour of R. A.
it runs in an irregular, patchy, and winding stream through
Aquila, Sagitta, and Vulpecula up to Cygnus. At e Cygni
its continuity is interrupted, and a very confused and
irregular region commences, marked by a broad, dark
vacuity not unlike the " Coal-sack " of the Southern hemi-
sphere, occupying the space between , a and y Cygni,
which serves as a kind of centre from which 3 great
streams diverge. Of these streams one has been already
traced ; a second, which is a continuation of the first
(across the interval) from a Cygni northwards, between
Lacerta and the head of Cepheus to the point in Cassio-
peia, whence we set out ; and a third branching off from
y Cygni, very vivid and conspicuous, running off in a
southerly direction through /3 Cygni and s Aquilae, almost
to the equinoctial, where it loses itself in a region thinly
sprinkled with stars, where in some maps the modern
constellation Taurus Poniatowskii is placed. This is the
branch which, if continued across the equinoctial, might
be supposed to unite with the great southern effusion in
Ophiuchus already noticed. A considerable offshoot or
protuberant appendage is also thrown off by the northern
stream from the head of Cepheus directly towards the
134 THE STORY OF THE STARS.
Pole occupying the greater part of the trapezium formed
by a, |3, i and 8 of that constellation.
In connection with the Milky Way a large amount of
speculation has been indulged in, but as Gore well re-
marks : " Many attempts have been made to form a sat-
isfactory theory of the construction of the Milky Way, but
these efforts have been hitherto attended with but little suc-
cess. This is not surprising, as the problem is evidently
one of great difficulty." Thomas Wright, of Durham, was
the first modern speculator. He started, about 1734, a
theory which, in a more matured form and worked out
with better materials, was put forward by Sir W. Herschel
about 1784 and became widely known as the " Stratum
theory " of the Milky Way, or, as some have called it, the
" Cloven disc theory." Briefly, his idea was that the stars
were not indifferently scattered through the heavens, but
were rather arranged in a certain definite stratum, com-
prised between 2 plane surfaces parallel to and near each
other but prolonged to immense distances in every direc-
tion, the thickness of which stratum, as compared with
its length and breadth, was inconsiderable ; and that the
Sun occupies a place somewhere about the middle of its
thickness, and near the point where it subdivides into 2
principal streams inclined to each other at a small angle.
This theory is not accepted in the present day,* and other
theories have been put forth. Proctor, whose strong
point was running down his rivals, suggested that the
form of the Milky Way was that of a spiral, but this no-
tion has been demolished by Sutton. Gould is disposed
to consider the Milky Way to be " the resultant of two or
* Proctor asserted that it was even given up by its author, but
Sir John Herschel, writing more than half a century afterwards,
reproduced it without any hint that it had been abandoned by his
father, and a son is a better authority as to his father's opinions
than a mere stranger, as Proctor was.
THE MILKY WAY. 135
more superposed galaxies," whatever that may mean. All
things considered, Gore's words are eminently wise :
" The Copernicus of the sidereal system has not yet ap-
peared, and it may be many years, or even centuries, be-
fore this great problem is satisfactorily solved." In point
of fact, for more than 2000 years astronomers (and others)
have been speculating as to the origin and nature of the
Milky Way. Metrodorus considered it to be the original
course of the Sun abandoned by him after the bloody
banquet of Thyestes ; others thought that it pointed out
the place of Phaeton's accident, whilst yet another class
regarded it as being made up of the ears of corn dropped
by Isis in her flight from Typhon. It seems hardly con-
sonant with our prosaic nineteenth-century thoughts to
transcribe such rubbish as this, yet these and kindred fa-
bles and fancies have taken deep root in the human mind,
though probably it is true that they do not possess the
ascendancy which they did even fifty years ago. There
were, however, others of the ancients who, though no
doubt painfully ignorant of physical science, as tested by
our modern standards, and impregnated with ideas of the
most ridiculous and fantastic character, did, at any rate,
do their best, according to their lights. For instance,
when Aristotle imagined the Milky Way to be the result
of gaseous exhalations from the earth which were set on
fire in the sky, who shall say that he did not prefigure
Huggins's conclusion that certain of the nebulas are
nought else but blazing masses of hydrogen or other ter-
restrial gases? It is more difficult, however, to find a
modern counterpart for the idea of Theophrastus, that it
is the soldering together of 2 hemispheres ; or for the con-
ception of Diodorus, that in gazing at the Milky Way we
see a dense celestial fire which shows itself through the
clefts which indicate that 2 hemispheres are about to burst
apart. It is, however, interesting to come upon specula-
136 THE STORY OF THE STARS.
tions by Democrates and Pythagoras that the galaxy was
neither more nor less than a vast assemblage of stars.
Ovid speaks of it as a high-road " whose groundwork is
stars." Manilius, who posed as an astronomical writer
about the first century of the Christian Era, and who was
probably a Roman, uses similar language. In a poem
which he wrote called the " Astronomicon," and which
has been more than once, I think, rendered into English,
we find the following allusion to the Milky Way :
" Or is the spacious bend serenely bright
From little stars, which there their beams unite,
And make one solid and continued light ? "
It is not a little curious how widely spread, both as
regards time and place, is the association of the idea of
milk with the Milky Way ; and though, no doubt, it may
be a case of one language supplying a word which others
borrowed and translated, yet this would hardly have been
done if the underlying idea had not proved acceptable.
The Greek name was Ta\aias or KVK\OS yakaKTiKos, which
the Romans converted into Circulus Lacteus or Orbis
Lacteus, whence no doubt our "Milky Way." At the
same time our English ancestors had several independent
names of their own. Amongst these were "Jacob's Lad-
der," "The way to St. James's," and " Watling Street."
The existence of these names supplies another proof, if
one were wanted, that the cardinal facts and features of a
science like astronomy often take a much deeper hold
over the popular mind than might be expected.
APPLICATION OF SPECTROSCOPE TO STARS. 137
CHAPTER XVIII.
THE APPLICATION OF THE SPECTROSCOPE TO THE
STARS AND NEBULAE.
THE subject covered by the above heading has of late
years grown to be a very large one, and it will only be
possible to exhibit here a bare outline. The spectroscope
was first applied to the stars by Fraunhofer about 1814.
His apparatus consisted only of a small prism placed in
front of the object glass of a telescope belonging to a
theodolite. The intervention of the prism changed the
image of the star from the bright point which it showed
when viewed by the telescope alone, into a narrow, bright
line which exhibited all the colours of the rainbow in their
customary order, from red at one end to blue at the other.
The formation of the spectrum, as this many-coloured line
is called, is easily understood. The light from a star con-
sists, not of rays of one colour alone, but of rays of an
infinite number of different colours. These, in the ordi-
nary course of things, follow the same path, enter the
telescope together, come practically to the same focus, or
nearly so, and produce a single and colourless image of
the star, because the combination of all the different col-
ours yields the sensation which we term white light. But
when the light of a star passes through a prism it becomes
bent out of its course, and the several different colours are
each differently affected, some being more bent from the
original straight line than others. Each separate coloured
ray then produces a separate coloured image of the star,
and these images no longer converge together to the same
point, but fall into position side by side, overlapping each
other.
Fraunhofer found, however, in the case of the stars, as
he had previously found on examining the light of the sun,
10
138 THE STORY OF THE STARS.
that the spectra of the stars were not quite complete, and
instead of the coloured line being absolutely continuous
from the red end to the violet end, it was interrupted here
and there by narrow dark spaces. These spaces, in the
case of the planets Mars and Venus, corresponded pre-
cisely with those spaces which he had already detected in
the spectrum of the sun, and this was natural, since the
planets only reflect to us the light which they receive from
the sun. But the gaps or dark lines in the spectra of dif-
ferent stars were not precisely identical with those to be
traced in the solar spectrum, and, moreover, the spectra
of different stars were different.
This was an important discovery, for it proved that the
source and cause of these dark lines depended on the sun
or on the various stars themselves, as the case might be ;
and was not due to anything in our atmosphere, or in ce-
lestial space, for in such case all the lines would have
been alike. Certain particular lines were indeed traced to
our atmosphere as they were invariably seen in the spec-
trum of any celestial body when it was near the horizon,
and was therefore being viewed through a great thickness
of terrestrial atmosphere.
Fraunhofer did not arrive at any explanation of the
cause of these lines, and a generation passed away before
Kirchhoff, in 1859, proved that a number of the solar lines
were due to the presence in the sun's atmosphere of the
glowing vapours of various metals, of which sodium and
iron seemed to be the chief.
The presence of a pair of bright lines in the orange-
yellow portion of the spectrum of a candle flame had long
been noticed. It had been proved that these were due to
sodium, and it had been shown that they corresponded
precisely in position to a pair of dark lines known as the
D lines in the spectrum of the sun. Kirchhoff succeeded
in showing that a glowing gas which, at a given tempera-
APPLICATION OF SPECTROSCOPE TO STARS. 139
ture, gives off light of a particular tint (or rather of a par-
ticular wave-length) possesses also at that temperature the
power of absorbing light of that same wave-length. The
surface of the sun (the " photosphere," as it is technically
called) emits light of every colour, but superposed on it
are the luminous vapours of various metals. These va-
pours, could we but see them alone, would give us only
light of certain particular colours their spectra would be
spectra of bright lines. But, looking through them at the
solar photosphere (which lies below), these gases shut off
from us light emanating from the photosphere of precisely
the same quality as they themselves emit. We find,
therefore, the solar spectrum crossed by dark lines, which
correspond to the bright lines of the gases of the solar at-
mosphere. The conclusion of the whole matter is that
whilst the two D lines show the presence of sodium, other
lines, known as C, F, G 1 , and h show the presence of hy-
drogen ; whilst iron, magnesium, and other elements have
also been severally detected in turn.
The same principle has now been applied to the spectra
of stars. In their case, as in the case of the spectrum of
the sun, the bright background of the continuous spec-
trum shows the presence of a stellar photosphere, the dark
lines crossing it the presence of particular gases in the
stellar atmosphere. But the work of identifying these
gases in connection with the stars was one of far greater
difficulty than it had been in the case of the sun, owing to
the light even of the brightest stars being comparatively so
feeble. This task was, however, undertaken by Huggins
and Miller with the utmost skill and patience, and hydro-
gen, sodium, magnesium, iron, calcium and other elements
which had been previously detected in the sun were shown
to exist in the atmospheres of Arcturus, Aldebaran, and
several other stars.
For such researches as those of Huggins and Miller
140 THE STORY OF THE STARS.
the object-glass prism of Fraunhofer was quite unsuited,
and a slit spectroscope was adopted. In this a very nar-
row slit occupies the focus of the telescope, so that the
image formed by the telescope falls upon it. The slit is
also in the focus of a small' object-glass placed behind it,
called the collimator, which renders the rays of light com-
ing from the star parallel to each other. The rays then
pass through one or more prisms and so become dis-
persed, the differently coloured rays undergoing a different
amount of bending out of their course. Finally the spec-
trum thus produced is viewed by means of a small tele-
scope. As the normal image of a star is only a point the
resulting spectrum is only a line, and a small breadth has
to be imparted to it by means of a cylindrical lens before
it can be successfully observed.
A labour of a different character was being undertaken
by Secchi at about the same time that Huggins and Miller
were at work. This distinguished Italian physicist found
that though the spectra of different stars differed in charac-
ter, these differences might easily be reduced to no more
than 3 or 4 simple types. Rutherfurd had made a similar
suggestion a little earlier, but Secchi was the first to carry
out a systematic spectroscopic examination of any con-
siderable number of stars. More recently, other and more
detailed classifications have been proposed by Vogel and
by Lockyer and as regards the photographs of stellar
spectra by Pickering, but these have in no way super-
seded Secchi's scheme of classes ; they have supplemented
it rather than replaced it.
Secchi divided the stars into 4 principal groups, which
he designated " Types " : (I.) The white or bluish stars,
of which Sirius may be taken as the type. These stars
yield spectra with the lines of hydrogen very broad and
dark, but the lines of the metals faint and difficult to see,
or altogether absent. (II.) The yellow stars, of which
APPLICATION OF SPECTROSCOPE TO STARS. 141
our Sun, Arcturus, and Capella may be taken as the chief
types. The spectra of these show the lines of hydrogen,
but not so broadly or prominently as in the case of the 1st
type ; the metallic lines are, however, on the other hand,
numerous and distinct. (III.) The orange stars, of which
a Orionis, a Herculis, and the variable star Mira Ceti are
types. This class also includes divers variable stars of
long or irregular period. The spectra are crossed by a
number of dark, bands, very dark and sharp on the side
nearest the blue, and shading off gradually towards the
red end. (IV.) The red stars, none of which are brighter
than 5th magnitude. These have spectra crossed princi-
pally by 3 dark bands, due to the absorption of carbon,
and shaded the reverse way to those of the Illrd type.
A number of small stars, distributed along the axis of
the Milky Way, and commonly called the " Wolf-Rayet "
stars, from the two French astronomers who found the
first examples, are now considered, in accordance with a
suggestion of Pickering's, to form, together with the
planetary nebulas, a Vth general type. These show very
characteristic spectra, the background being of irregular
brightness and crossed by two bright lines in the yellow,
by another in the light green, and by a distinctive bright
band in the blue.
There are also a few stars which can scarcely be
brought under any of the foregoing five heads. For in-
stance, many of the stars in Orion have the hydrogen as
well as the metallic lines narrow and faint ; they can
therefore hardly be placed under either the 1st or Ilnd
types. And it may be added that y Cassiopeias, /3 Lyras,
and a few other stars show the hydrogen lines bright.
Secchi's catalogue contained about 500 stellar spectra,
but this number has been very largely increased by Vogel,
who has informed us concerning the spectra of about
4000 stars ; whilst Konkoly has dealt with about 2000
142 THE STORY OF THE STARS.
stars. All the foregoing were the result of direct eye ob-
servation, but a fuller survey has since been accomplished
by means of photography. Huggins at an early period
applied photography to the study of stellar spectra, and
discovered thereby a remarkable series of broad, dark
lines in the ultra-violet region of spectra of stars of the
Sirius type. Dr. Henry Draper worked on similar lines at
about the same time, and after his death his widow placed
ample funds at the disposal of the Harvard College ob-
servatory for further researches to be carried on in memory
of her late husband. One of the results of her generosity,
and of Pickering's skilful use of it, is the " Draper Cata-
logue," a classified catalogue of the photographed spectra
of more than 10,000 stars. The classification adopted is
somewhat more detailed than Secchi's, but proceeds on
essentially the same lines.
In a previous chapter (XII.) I have said a good deal
about that remarkable class of objects commonly called
the temporary stars, or Nova stars which have suddenly
come into view and have then rapidly faded away. Only
a few instances have occurred since the application of the
spectroscope to stellar observation, and the stars have all
been much less bright and enduring than Tycho's famous
star of 1 572, but striking characteristics have been exhib-
ited by each of those which have been spectroscopically
treated.
The spectrum of T Coronas in 1866 showed, besides
a continuous spectrum crossed by dark lines, a number
of bright lines, amongst which those of hydrogen were
clearly to be noticed. In Nova Cygni in 1876, again, a
number of bright lines were seen superposed on a con-
tinuous spectrum. These bright lines appeared on the
whole to correspond to those of the solar chromosphere
(the narrow red fringe seen surrounding the sun's disc
during a total solar eclipse). The hydrogen lines, and a
APPLICATION OF SPECTROSCOPE TO STARS. 143
characteristic line in the yellow, near the D lines of so-
dium, and called Da (or the " Helium " line), were the
most conspicuous. It must be noted in this connection
that the hydrogen lines with the D 3 line are also the chief
lines exhibited by the "red flames," or "prominences,"
which are often seen to rise from the solar chromosphere
to heights of 100,000 miles or more. It follows from this,
therefore, that T Coronae and Nova Cygni seemed to offer
evidence that stars are not only sometimes composed of
the same elements as the sun, and, like it, possess pho-
tospheres surrounded by absorbing gases, but also that
they possess chromospheres and prominences, so that, in
point of fact, the sudden development of brilliancy re-
corded in the case of these 2 stars was really in the
nature of a prodigious chromospheric outburst.
Nova Cygni, however, underwent further changes.
When its continuous spectrum had nearly faded out the
aspect of the spectrum that remained greatly resembled
that of the Wolf-Rayet stars. Later still, in the autumn
of 1877, the light of the star appeared concentrated in a
single bright line, apparently the line characteristic of the
nebulas.
Near the centre of the great nebula in Andromeda a
new star became visible in August, 1885. Its spectrum
was practically continuous.
Two other Nova have yet to be mentioned, Nova Au-
rigas and Nova Normas, the last named apparently a faint
copy of the first. Nova Aurigae stands out as perhaps
the most interesting and most perplexing object yet stud-
ied by aid of the spectroscope. Discovered by Dr. Thomas
Anderson on January 24, 1892, but recorded by the auto-
matic stellar camera of Harvard College on December 10,
1891, it showed, when subjected to spectroscopic analysis,
the twofold spectrum seen in T Coronas and Nova Cygni,
a continuous spectrum crossed by dark lines, and a spec-
144 THE STORY OF THE STARS.
trum of bright lines, amongst which those of hydrogen
were conspicuous, together with many of the principal
lines of the solar chromosphere.
The star diminished in brightness very quickly after
March 16, 1892, and was unfavourably placed for some
months. When it was examined afresh on August 17 by
the Lick observers, it was found to have undergone a par-
tial revival, and, as in the case of Nova Cygni, they
thought its spectrum closely resembled that of a planet-
ary nebula. Huggins, however, did not regard this con-
clusion as fairly established. The spectrum showed, it is
true, two bright bands near the positions of the two chief
nebular lines, but the bands were really groups of bright
lines, extending over a- considerable length of the spec-
trum. The most striking feature of the spectrum of
Nova Aurigae was the displacement of its lines. As first
seen, the bright hydrogen lines were accompanied by
dark absorption lines, manifestly due to the same element,
but displaced towards the violet as compared with the
bright lines. Photographs of the spectrum revealed
further details. Many of the dark lines carried a fine
bright line upon them ; many of the bright lines could be
resolved into two or three components. Here, then,
there was at least a double hydrogen spectrum : one of
dark lines, the other of bright lines, the two displaced
with regard to each other. Possibly there were several
such distinct spectra. How were their displacement with
regard to each other to be explained ?
Doppler, in 1843, had shown that the motion of a
source of light towards the observer must cause a short-
ening of the intervals between the waves of light. In
other words, light of a given special wave-length would
have that wave-length diminished, and the light would
appear to have shifted its place in the spectrum towards
the blue end if the source of the light were in motion
APPLICATION OF SPECTROSCOPE TO STARS. 145
towards us. If we adopt this explanation of the com-
posite spectrum of Nova Aurigas it follows that that star
must have consisted of two or more bodies moving in
different directions in the line of sight with the most
amazing velocity. The body giving the dark absorption
lines would appear to have been approaching our system
at a speed of 400 or 500 miles a second, and the body
giving the bright lines to have been receding at a speed
of about 300 miles a second.
This is scarcely the place to bring forward in detail
theories to explain these complicated spectra. The two
most favoured are the " tidal theory," which supposes
that the near approach of two great stars to each other
has given rise to immense tidal waves of highly heated
gas, and the " cosmical cloud theory," according to
which these Nova are due to the rush of a swiftly moving
star through a nebula.
Doppler's principle (as has already been briefly men-
tioned in a previous chapter) had been applied to a differ-
ent problem by Huggins in 1867, who carefully compared
the position of the green line of hydrogen as given by a
vacuum tube, with that of the same line in the spectrum
of Sirius. Later on he examined the spectra of a number
of stars, and calculated from the amounts and direction of
the displacement of the lines in their spectra, the speed at
which the separate stars were moving towards us, or
away from us in the line of sight. This research was
then taken up at Greenwich and at Rugby, but with in-
sufficient means. Lastly, Vogel pressed photography
into the service, and made some very successful observa-
tions on about 50 stars.
One result of Vogel's work was the discovery of " spec-
troscopic double stars." The variable star, Algol, had
long been suspected to have a dark companion, which by
transiting before its primary caused a partial eclipse every
146 THE STORY OF THE STARS.
69 hours. Vogel now conclusively showed that this was
the case, for Algol was moving round the centre of gravity
of the pair in precisely the time required, and the diame-
ter, mass, distance from its primary, and speed in its orbit,
of the unseen companion, were all computed.
Spica Virginis proved to be another close double,
though in this case the companion does not obscure the
bright principal star. Indeed, it is possible that it is as
bright as the 3rd magnitude.
In some cases a " spectroscopic double " is composed
of two stars of nearly equal brightness. This is the case
with f Ursae Majoris and /3 Aurigae, which were discovered
by Pickering a little before Vogel's proof of the existence
of the companion of Algol. The two stars which make
up /3 Aurigas revolve in an orbit which is but little inclined
to the line of sight. Consequently at one time one star
will be approaching us in its orbit whilst the other is re-
ceding. The lines due to the first star are displaced
towards the blue, and those of the second towards the
red, and the lines in the compound spectrum are therefore
double. A little later both bodies are moving across the
line of sight, and therefore are neither approaching us nor
receding from us, so that the lines of the two stars exactly
coincide. The period in the case of this star is nearly 4
days.
Another probable " spectroscopic double " is the vari-
able star (3 Lyrse. This star (as we have already seen)
goes through its changes in a little less than 13 days, hav-
ing two maxima and two minima. Its spectrum shows
broad, dark bands, due to hydrogen, besides bright lines,
which change their appearance and position from time to
time. It has been suggested that the system consists of
two stars of unlike spectra revolving round each other,
and partially eclipsing each other as they cross the line of
sight. The changes of the spectrum are, however, very
APPLICATION OF SPECTROSCOPE TO STARS. 147
complicated, and have not yet been completely studied,
and so simple an explanation appears scarcely adequate.
A very promising and important study is that of the
distribution of the different types of stellar spectra. For
this the available material is as yet insufficient. Never-
theless, the Draper catalogue, and the catalogues of Vogel
and Konkoly, have enabled some first approximations to
be made. It appears, from a consideration of such binary
stars as have been spectroscopically examined, that the
1st or Sirius type of stars are much less dense relatively
to their brightness than the Solar stars, or are intrinsically
brighter relatively to their density. The Ilnd type of
stars, i. e., the Solar stars, and to a less degree the Illrd
type of stars, appear to be pretty evenly distributed over
the sky. The 1st, or Sirius type, shows a distinct disposi-
tion to aggregation towards the Milky Way, whilst, as
already pointed out, the Wolf-Rayet stars cluster along its
axis. The proper motions of the Sirius stars appear to be
smaller than those of the Solar stars, which from this
and other reasons may be supposed to be on the average
nearer to us than the Sirius stars. If the Solar type stars
be divided into two classes, according to their greater
resemblance to Capella and Arcturus respectively, the for-
mer class appears to have a larger average proper motion
than the latter, and may therefore be supposed to be the
nearer stars. The entire subject, however, needs much
fuller investigation before any great weight can be at-
tached to these provisional conclusions. The completion
of the Draper catalogue by the publication of the results
of the survey of the southern heavens carried out at Are-
quipa, in Peru, under the direction of the Harvard astrono-
mers, will constitute the next important forward step.
The first observation of the spectrum of a nebula was
made by Huggins in August, 1864. The object examined
was the small, bright, planetary nebula in the pole of the
148 THE STORY OF THE STARS.
ecliptic, 37 ip IV Draconis, to which some allusion has
already been made. The first scrutiny revealed the fact
that there existed an immense difference between its
spectrum and an ordinary stellar spectrum. In place of
the usual continuous spectrum only three isolated bright
lines were seen a proof of the presence of luminous gas.
In other words, the object was a true nebula, that is, a
mass of glowing gas, and not a star cluster, seeming to be
nebulous only on account of its distance.
Of the three lines, one, the faintest, was evidently due
to hydrogen. The other two have not yet been identified,
but the brightest is very near one of a pair of green lines
in the spectrum of nitrogen, and has hence been sometimes
spoken of as the "nitrogen line." Other lines due to
hydrogen have since been observed in various nebular
spectra, together with the well-known chromospheric line
Da, A number of other lines have also been detected in
the visual spectrum with extreme difficulty by different
observers, and many more by means of photography in
the violet and ultra-violet regions. The sources of these
lines have not yet been ascertained, and in a great number
of the fainter spectra the line in the green near the nitrogen
pair, which is especially to be regarded as the typical
nebular line, is alone visible.
The problem of the motions of the nebulas in the line
of sight has been attacked by Keeler at the Lick Observa-
tory. He has measured the displacement of the chief
nebular line in the spectra of the nebulae, and has obtained
evidence of movements varying from a speed of about 40
miles per second of approach, to about 30 miles per
second of recession.
Several of the nebulae, as, for example, the great nebula
in Andromeda, show continuous spectra. But many of
those that give a spectrum of bright lines give also a faint,
continuous spectrum. The great nebula of Orion is one
APPLICATION OF SPECTROSCOPE TO STARS. 149
of the latter class, though Huggins considers that the
seemingly continuous spectrum is resolvable into lines.
Other nebulas show bright lines only, without any trace of
continuous spectrum.
In the case of the great nebula in Orion Huggins has
secured some photographs of exceptional interest, which
show that the stars of the "trapezium " are not merely
apparently in the nebulae, but really so, for a number of
bright lines (one in particular, with a wave-length of 3730
" tenth metres ") were observed both in the continuous
spectrum of two of the trapezium stars, and in the spec-
trum of the nebulae in their immediate neighbourhood. A
later photograph, taken in 1889, in which the slit of the
spectroscope was pointed near to the trapezium, but not
actually across it, failed to shew the 3730 line, which
would thus appear to be typical only of the regions of the
nebulas close to the stars. It would seem probable, there-
fore, that these stars are involved in the nebulae.
The subject of spectroscopic observations of the stars
and nebulae is a growing one, but we have yet much
more to do before we can much more learn.
APPENDIX I.
TABLE OF THE CONSTELLATIONS.
BY the entries in the column headed " Centre " it is
meant to be inferred that a line of Right Ascension and a
line of Declination taken off the map will intercept at a
point which may be regarded as about the centre of the
constellation. This, however, is only true of the more
compact constellations, for there are some, like Draco,
Cetus, and Argo, which are so long and straggling that
they extend over several hours of R.A. When, therefore,
I state that the constellations are here arranged in the
order of R.A., the statement must be regarded as need-
ing some qualification in many cases. In the column of
" Declination " + means North, and South.
NAME OF CONSTELLATION.
CENTRE.
R.A.
Decl.
Pisces .
h. m.
O 2O
o 30
o 40
I
I O
i 45
2
2 25
2 30
2 40
3 20
+ 10
-35
+ 38
- 4 8
+ 60
12
432
33
+ 20
-72
+ 42
Sculptor [Apparatus Sculptoris]
Andromeda
Phoenix
Cassiopeia
Cetus
Triangulum
Fornax [Chemical
Perseus
150
THE CONSTELLATIONS.
NAME OF CONSTELLATION.
CENTRE.
R.A.
Decl.
h. m.
3 20
3 50
3 5
4 30
4 40
5 o
5 20
5 25
5 30
5 40
5 40
5 40
6 o
6 40
7 o
7 o
7 30
7 40
7 50
8 o
8 30
8 40
8 40
9 o
9 30
10 O
10 10
10 20
10 30
10 40
II
II
II 20
12 2O
12 30
12 30
12 40
13
11 20
-52
-63
30
+ 18
-42
60
+ 3
20
52
-77
-34
-f 70
+ 42
-24
+ 24
3
+ 6
-32
+45
40
+ 20
62
-69
30
-45
-35
i
+ 33
+ 15
-78
12
+ 5 8
15
60
-18
-68
-27
+ 40
47
Reticulum fRhomboidalisl
Dorado
Lepus
Pictor [Equleus PictorisJ
Mensa TMons Mensa] ..
Columba [Noachil
Camelopardus
Canis Minor
Lynx
Cancer
Argo [Carina]
Volans [Piscis Volans]
Argo [Malus]
Argo [Vela]
Antlia Pneumatica
Sextans
Leo
Hydra
Ursa Major
Crux
Cor/us
Canes Venatici
Centaurus.. .
'52
APPENDIX I.
NAME OF CONSTELLATION.
CENl
RE.
R.A.
Decl.
h. m.
11 2O
2
Bootes
14 IS
-4-7O
Circinus
14 So
_6i
is o
4O
15 10
I/I
IS IO
76
Serpens .
IS TS
f 8
Corona Borealis
I S .IO
4- IO
Triangulum Australe
IS: 4O
6s
Ursa Minor
IS 4O
+ 78
Norma
16 o
d.O
Draco
16 o
+ 60
16 20
26
16 50
ss
Ophiuchus
17 10
4,
17 10
+ 27
Corona Australis
18 30
41
18 10
IO
Telescopium
18 40
S2
Lyra
18 dc.
+ ^6
IQ O
2S
Pavo
IQ IO
6s
Aquila (with Antinoiis)
IO ^O
+ 2
Sapitta. . .
IQ SO
-fiS
Vulpecula et Anser
2O IO
+ 2S
2O V3
+ 4O
2O IS
4-12
2O 5O
2O
21 O
"37
21 IO
4- 6
21 2O
s8
21 4.O
^2
22 O
+ 70
Grus
22 2O
47
22 2O
1^
22 2S,
+ 41
22 ^O
+ 17
23 45
68
Octans
Polar
(South)
APPENDIX II.
LIST OF CELESTIAL OBJECTS FOR SMALL TELE-
SCOPES.*
IT is here assumed that a certain number of the read-
ers of this volume may happen to possess a small tele-
scope, and would be glad to direct it on celestial objects
of interest if they knew where to look for some which
were within the reach of their instruments. Hence the
motive for the compilation of this catalogue, which may
be said to represent the capacity of portable refracting
telescopes of about 2 inches in aperture.
(l) DOUBLE OR COMPOUND STARS.
Right
Declina-
Magnitudes
Distance
No.
NAME OF STAR.
Ascen-
tion,
of Com-
between the
sion, 1890.
1890.
ponents.
Components.
h. m. s.
o /
//
I
Toucani
o 26 30
-63 34
Both 5
28
2
TJ Cassiopeiae
o 42 26
+ 57 13
4 and 7$
5
3
7 Arietis
I 47 29
+ 18 45
4i and 5
8
4
7 Andromedee
I 57 8
+ 41 48
3| and 5$
( 10 : B.
( double.
5
Eridani
2 54 5
40 44
5 and 6
8
6
14 Aurigae
5 8 14
-1-32 33
5 and 7^
14
7
23 Orionis
5 17 3
+ 3 26
5 and 7
8
8 Orionis
5 26 23
O 22
2 and 7
53
* For a comprehensive general catalogue of objects of this kind,
with full descriptions of each, see Admiral W. H. Smyth's " Cycle
of Celestial Objects," 2nd ed., Oxford, 1881, price 125.
II 'S3
APPENDIX II.
No.
NAME OF STAR.
Right
_Ascen-
sion, 1890.
Declina-
tion,
1890.
Magnitudes
of Com-
ponents.
Distance
between the
Components.
h. m. s.
/
//
9
<r Orionis
5 33 3
2 38
4, 8 and 7
( 12 and 42 :
/ multiple.
10
ii Monocerotis
6 23 29
- 6 57
6J, 7 and 8
j 7,9 =
1 (B.C.=2. 5 )
ii
7 Volantis
7 9 40
-70 19
5 and 7
13
12
a Geminorum
7 27 35
+ 32 7
3 and 3-^
5
13
7 Argfis
868
47 o
2 and 6
42
14
54 Leonis
10 49 39
+25 20
4i and 7
6
15
a Crucis
12 20 28
62 29
ii, 2 and 5
5,90:
quintuple
16
17 Comae Ber.
12 23 25
+ 26 30
4-J and 6
. 145 [use
low power]
17
7 Crucis
12 25 2
56 29
2 and 5
1 20
18
7 Virgin is
12 36 5
o 50
both 4
5
19
a Can. Venat
12 50 53
+ 38 54
2-J and 6
20
514 ; Alcor,
20
Ursse Maj.
13 19 29
+ 55 30
3 and 5
mag. 5, is
distant nf
21
a Centauri
14 32 7
DO 22
I and 2
14
22
IT Bootes
14 35 33
+ 16 53
3i and 6
5
7 * A. nlso
23
Scorpii
15 58 19
ii 4
4^ and "]\
double
T . A 1 _
24
j8 Scorpii
15 59 2
-19 30
2 and si
13 i ** aiso
double
I 40 ; both
25
v Scorpii
16 5 36
19 10
4 and 7
-| double
( 0.7, 2
26
36 (A) Ophiuchi
17 8 34
26 25
4i and 6i
4
27
a Herculis
17 9 38
+ 14 30
3-J and si
4
28
CLyne
18 40 59
+ 37 29
S and s
44
29
Serpentis
18 50 49
+ 43
4-J- and 5
21
30
/3 Cygni
19 26 17
+ 27 43
3 and 7
34
31
a 9 Capricorn!
20 ii 57
-12 53
3 and 4
j 376 [use
( low power]
32
/S 2 Capricorni
25 14 5
-15 7
3i and 7
205
33
7 Delphini
20 41 33
+ 15 43
4 and 6J-
ii
34
/3 Cephei
21 27 14
+ 70 43 and 8
13
35
8 Cephei
22 25 5
+ 57 5i4i and 7
40 : A. var.
LIST OF CELESTIAL OBJECTS.
'55
(2) CLUSTERS OF STARS AND NEBULAE.
No.
DESIGNATION OF OBJECT.
Nature of
Object.
Right As-
cension.
Declina-
tion.
h. m. s.
/
I
47 Toucani
Cluster
o 19 9
-72 41
2
31 M. Andromedae
Nebula
o 36 47
+ 40 40
3
The Nubecula Minor
o 48 41
-73 58
4
103 M. Cassiopeiae
Field of stars
i 25 56
+ 60 7
5
33 ]$. VI Persei
Double cluster
2 II 2O
+ 56 38
6
i\ Tauri
Group of stars
3 40 56
+ 23 45
7
Nubecula Major
5 24 6
69 34
8
I M. Tauri [" Crab "]
Nebula
5 27 51
+ 21 56
9
42 M. Orionis
Nebula
5 29 52
5 27
10
35 M. Geminorum
Cluster
624
+ 24 26
ii
41 M. Canis Majoris
Cluster
6 42 13
-20 37
12
" Praesepe " in Cancer
Cluster
8 33 55
+ 20 19
13
i) Argus
Nebula
10 40 47
59 6
14
K Crucis
Cluster
12 47 7
-59 45
15
o> Centauri
Cluster
13 20 10
46 44
16
3 M.Canum Venaticorum
Cluster
13 37 3
+ 28 55
I?
5 M. Librae
Cluster
15 12 57
+ 2 30
18
80 M. Scorpii
Cluster
16 10 26
-22 43
19
13 M. Herculis
Cluster
16 37 45
+ 36 39
20
92 M. Herculis
Cluster
17 13 46
+ 43 15
21
14 M. Ophiuchi
Cluster
17 31 50
- 3 ii
22
8 M. Sagittarii
Cluster
17 57 8
24 22
23
24 M. Scuti Sobieskii
Cluster
18 ii 44
18 26
24
17 M. Scuti Sobieskii
Nebula
18 14 16
16 14
[" Horse-shoe "]
25
22 M. Sagittarii
Cluster
18 29 28
23 59
26
II M. Antinoi
Cluster
18 45 13
6 24
27
57 M. Lyrae
Annular neb.
18 49 28
+ 32 53
28
27 M. Vulpecula
Nebula
19 54 48
+ 22 25
[" Dumb-bell "]
2 9
15 M. Pegasi
Cluster
21 24 38
+ 11 40
30
2 M. Aquarii
Cluster
21 27 44
- I ig
i 5 6
APPENDIX 11.
(3) SPECIAL STARS.
No.
NAME OF STARS.
Right
Ascension,
1890.
Declina-
tion,
1890.
Mag.
Notes.
h. m. s.
/
I
oCeti
2 13 47
3 28
Var.
Max. mag. 2 :
Fiery red. In-
visible at Min.
2
aCeti
2 56 31
+ 3 39
2i
Orange colour
3
$ Persei
312
+ 40 31
Var.
Max. 2 : Min. 4
4
5 Lyncis
6 17 12
+ 8 28
5i
Fiery red
5 fj. Canis Majoris
6 51 3
13 54
Sir
Fiery red
6
20918 Lai. Hydrae
10 46 16
20 37
7
Copper coloured
7
/3 Librae
15 ii 5
8 58
2*
Pale green
8
a Scorpii
16 22 39
26 ii
I
Fiery red
9
xCygni
19 46 20
+ 32 38
Var.
Max. 4: Min. in-
visible
10
/* Cephei
21 40 8
+ 58 16
Var.
Max. 4 : Min. 6 :
Deep garnet
colour
ii
5 Cephei
22 25 5
+ 57 5i
Var.
Max. 3^: Min. 4^
12
8 Andromedae
23 12 38
+ 48 24
5
Fiery red
13
30 Piscium
23 56 ig
- 6 37
4i
Fiery red
GENERAL INDEX.
A.
Achernar (a Eridani), 24.
Airy, Miss, 103.
Alcyone, one of the Pleiades, 103.
Aldebaran (o Tauri), 23, 24, 32, 33,
Algol 03 Persei), 32, 33, 86, 145.
Almanacks, based on astronomy, 10.
Altair (a Aquilse), 24, 25.
Amos. Prophecy of, cited, 40, 102.
Andromeda (constellation), 32, 34,
Great Nebula in, 79. 116, 148.
Angle of position of double star, 54.
Annular Nebulaej 115.
An tares (a Scorpii), 23, 24, 25, 34.
Antinous, 152.
Antlia Pneumatica (constellation),
151.
Apparatus Sculptoris (constellation),
150.
Apparent movement of the heavens,
n.
Apus (constellation), 152.
Aquarius (constellation), 35.
Aquila (constellation), 34.
Ara (constellation), 152.
Arago, 92.
Aratus, 42.
Arcturus (a Bootes), 23, 24, 34, 70,
71, 141.
Argelander, F. G. A., 43, 85.
Argo (constellation), 151.
Great Nebula in, 124, 129.
jf. Variable in, 88.
Aries (constellation), 33, 35, 39.
First point of, 37.
Aristotle, 135.
Ascension, Right, 37.
Atlases, Celestial, 39.
Auriga (constellation), 151.
Auwers, A, 103.
Axis of the heavens, 15.
Azimuth, 18.
B.
Bayer, J., his Atlas, 85.
his lettering of the stars, 23.
Bessel, F. W., 58.
Betelgeuse (a Orionis), 24.
Bible, References to, 40, 102.
Binary stars, 55.
Biot, E., 77.
Birmingham, J., 78.
Bond, G. P., 117.
Bootes (constellation), 152.
Bradley, J., 71.
Brisbane, Sir T. M., 88.
Burchell, his observations of ij Ar-
gus, 88.
Byron, Lord, Quotation from, 99.
C.
Caela Sculptoris (constellation), 151.
Camelopardus (constellation), 151.
Cancer (constellation), 35.
Canes Venatici (constellation), 151.
Canis Major (constellation), 33.
Canis Minor (constellation), 33.
Canopus (a Argus), 24.
Capella (a Aungae), 24, 25, 32, 167.
Capricornus (constellation), 34.
Cassiopeia (constellation), 31-, 32.
Castor (o Geminorum), 34, 35.
Centaurus (constellation), 151.
Central sun hypothesis, Madler's,
Cepheus (constellation), 31, 32.
Cetus (constellation), 34, 35.
Mira, Variable in, 84, 141.
Chacomac, 116.
Chaldean astronomy, 41.
Chamaeleon, 151.
Chandler, 86, 92.
157
158
GENERAL INDEX.
Chinese observations referred to, 41,
>7 6.
Circinus (constellation), 152.
Clusters of stars, 101.
List of, for small telescopes, 155.
Coal Sack. The. 131.
Coloured stars, 62.
Columba Noachi (constellation), 33.
Coma Berenices (constellation), 106.
Compass, Points of, 17-20.
Complementary colours, 65.
Constellations, 28.
Constellations, List of, 150.
Brief account of, 30.
Corona Australis (constellation), 152.
Corona Borealis (constellation), 34.
Corvus (constellation), 151.
Crab Nebula in Taurus, 122.
Crater (constellation), 151.
Crux (constellation), 151.
Cygnus (constellation), 32.
D.
Declination, 36.
Delphinus (constellation), 34.
Deneb (a Cygni), 24.
Diodorus, 135.
Diurnal Movement, 13.
Doppler, 72, 144.
Dorado (constellation), 151.
Nebula in, 123.
Double stars, 51, 65.
Draco (constellation), 32, 42.
Draper, Dr.. 142.
''Dumb-bell" Nebula, 127.
E.
Egyptian Astronomy, 40.
Elliptic Nebulae, 115, 116.
Eriqanus (constellation), 151.
Espin, T. E., 93.
F.
"Fixed" stars, 12.
Fomalhaut (a Piscis Australis), 23,
24, 25. 34-
Fontenelle, 69.
Fornax Chemica (constellation), 150.
Fraunhofer, 137.
G.
Galaxy, 49 (see Milky Way).
Gauging the heavens, 47.
Gemini (constellation), 33, 35.
Genesis xv, 5 cited, 43.
Globular clusters, 107.
Goodricke, 86, 87.
Gore, J. E., 81, 95, 135.
Gould, B. A., 134.
Grant, R., 44.
Gravitation as applied to binary
stars, 56.
Greenwich Observatory, 10.
Grus (constellation), 152.
Greek alphabet, 23, 30.
H.
Halley, E., 70, 88.
Hercules (constellation), 34.
cluster 13 M. in, 106, 155.
cluster 92 M. in, 155.
Herschel, Sir W., 46, 53, 55, 73, 74,
107, 108, 113, 119, 134.
Herschel, Sir J. F. W., 46, 63, 67, 88,
106, III, 114, 117, 121, 122, 123,
124, 125.
Herschel, Capt. J., 125.
Hesiod, 42.
Hjnd, J. R., 78, 92, 104, 121.
Hipparchus, 77.
Holden, E., 120.
Huggins, W., 73, 74, 92, 116, 135,
139, 140, 144, 147.
Hyades, The, in Taurus, 33, 102, 105.
Hydrus (constellation), 150.
I.
Indus (constellation), 152.
J-
Jacob's Ladder, name for Milky
Way, 136.
Job ix, 9 cited, 40, 102 ; xxxviii.
31-2, 40, 102.
K.
Key, Rev. H. C., 121.
Kirchhoff, 138.
Klein, H. J., his Atlas referred to,
39-
Konkoly, 141.
L.
La Caille, N. L., 88, 108.
Lacerta (constellation), 152.
Leo (constellation), 33, 35.
Leo Minor (constellation), 151.
Lepus (constellation), 151.
Libra (constellation), 35.
Lockyer, J. N., 140.
Longfellow, Quotation from, ico.
Lupus (constellation), 152.
GENERAL INDEX.
159
Lynx (constellation), 151.
Lyra (constellation), 152.
quadruple star, e, 60.
Annular Nebula in, 115.
M.
Madler, J. H., 74-
Magellanic Clouds, 127.
Magnitudes of stars, ai.
, List of stars of the first, 24.
Maia (one of the Pleiades), 103.
Manilius, his description of the
Milky Way, 136-
Mazzaroth, Meaning of, 41.
Mechain, 108.
Meridian, 17, 37.
Messier, his catalogue of nebulae,
108, 122.
No. i, 122, 155.
No. 5, 108.
No. n, 113, 155.
No. 13, 106.
Metrodorus, his idea of the Milky
Way, 135.
Micromete_r, 54.
Microscopium (constellation), 152.
Milky Way, its course amongst the
stars, 80, 129.
Theories of, 134.
Various old names of, 136.
Miller, W. A., i3Q t 140.
Milton, J., Quotations from, 97.
Mira (o) Ceti, 84, 156.
Monoceros (constellation), 151.
Mons Mensae (constellation), 151.
Montanari, 86.
Moore, T., Quotations from, 99.
Motions of the stars, apparent, n.
in the line of sight, 146.
Multiple stars, 62.
Musca Australis (constellation), 151.
N.
Naked eye, Number of stars visible
to, 12, 43, 45.
Nautical Almanac referred to, 10.
Nebulae, 114.
Spectroscopic observations of,
129, 147.
, alleged to be variable, 129.
for small telescopes, 155.
Nebulous stars, xai.
New stars, 142.
Norma (constellation), 152.
Nubecula Major, 127.
Nubecula Minor, 127.
Number of the stars visible to the
naked eye, 12, 43.
O.
Octans (constellation), 152.
" Omega" Nebula, 126, 129.
Ophiuchus (constellation), 34.
Hind's Nova in, 78.
" Orbis Lacteus," 136.
Orbits of double stars, 56.
Orion (constellation), 33.
Great Nebula in, 122, 129, 149.
Ovid, Quotations from, 103, 136.
P.
Palitzch, observes Algol, 86.
Parallax, Stellar, 26. 27, 55.
Pavo (constellation), 152.
Pegasus (constellation), 32, 34, 35.
Perpetual apparition, Circle of, 14.
Perpetual occultation. Circle of, 14.
Perseus (constellation), 150.
Cluster in, 101.
Phoenix (constellation), 150.
Photography as applied to stars, 49.
Pickering, E. C., 22, 82, 86, 140.
Pictor (constellation), 151.
Pigott, his theory of variable stars,
91.
Pingre, A. G., 77.
Pisces (constellation), 35.
Australis (constellation), 152.
Volans (constellation), 151.
Planetary nebulae, 118.
Pleiades, 32 34, 35, 102.
referred to in Job and Amos,
102.
possibly the centre of the Solar
System, 75.
mentioned by Homer, 102.
nebulae in, 103.
Pogson, N., Account of nebula in
Scorpio, 109.
Pole-star, Polaris (a Ursae Minoris)
12, 3 1 . 33, 34-
Pole, North, 13.
, South, 13.
Pollux 03 Geminorum), 24, 34.
Position, Angle of, 54.
Prxsepe in Cancer, 102, 105.
Precession of the Equinoxes, 37.
Pritchard, Rev. C., 22.
Proctor, R. A., 134.
Procyon (a Canis Minoris), 24, 33, 57.
Proper motions of stars, 67.
Pythagoras, his speculations as to
the Milky Way, 136.
Q.
Quadruple stars, 60.
i6o
GENERAL INDEX
R.
Red stars, 63, 66 { 141.
Regulus (a Leoms), 24, 25, 33, 34, 35.
Rigel O Orionis), 24.
Right Ascension, 36.
Rooerts, I., his photographs, 117, 127.
Rosse, Earl of, various observations
by, 106, 115, 117, 118, 119, 121.
Russell, H. C., his account of K Cru-
cis, 114.
S -
Sagitta (constellation), 152.
Sagittarius (constellation), 35.
nebulae in, 125.
Schiaparelli, 104.
Schmidt, J. F. )., 78.
Schonfeld, E., no.
Scorpio (constellation), 35.
cluster 80 M, 108.
Sculptor alias Apparatus Sculptoris
(constellation), 150.
Scutum Sobieskii (constellation), 152.
Nebula in, 126.
Secchi, A., 45, 116, 123, 140.
his classification of star spectra,
140.
Seidel, 22, 44.
Serpens (constellation), 152.
Sextant (constellation), 33.
Shakespeare, W., Quotations from,
95-
Shelley, Quotations from, 99.
Signs of the Zodiac, 38 (see Zodiac).
Sinus (a Canis Majoris), 24, 25, 27,
57, 70, 91, 140.
Smyth, Admiral W. H., 106, 108, 112,
"3-
Spectroscopic observation of stars,
I 37-
of nebulae, 147.
Spica (a Virginis), 24, 25, 34, 35.
Spiral Nebulae, 115, 117.
Stars, Double, 51, 52, 64.
Binary, 55.
Triple, 56, 59.
Multiple, 62.
Coloured, 62.
Variable, 83.
Temporary, 75, 109, 142.
Brilliancy of, 21.
Motions of, 67.
Names given to, 23.
Struve, F. G. W.. 48.
- L T.
Taurus (constellation), 33, 34, 35.
" Crab " Nebula in, 122.
Telescopes, List of objects for, 153.
Telescopium (constellation), 152.
Tempel, W., 103.
Temporary stars, 75, 109.
Tennyson, Quotations from, 100.
Ternary stars, 57.
Theophrastus, hislidea of the Milky
Way, 135.
Thomson, Quotations from, 100.
Time, Measurement of, 9.
Toucan (constellation), 152.
globular cluster in, in.
Trapezium in Orion, 62.
Triangulum (constellation), 151.
Australe (constellation), 152.
Triple stars, 60.
Tycho Brahe, 77.
Types, Secchi's four, 140, 147.
Ursa Major (constellation), 14, 29, 31.
- planetary nebula 7 M in, 119.
Ursa Minor (constellation), 31.
V.
Variable stars, 83, 145, 146.
- nebulae, alleged, 129.
Vega (a Lyrse), 24, 25, 34.
Vertical, t6.
Virgo ^constellation), 33, 35.
Vitruvius cited, 15.
Vogel, 140, 145.
Volans alias Piscis Volans (constel-
lation), 151.
Vulpecula (constellation), 132.
- " Dumb-bell" Nebula in, 127.
W.
"Watling Street," name of the
Milky Way, 136.
" Way to St. James's," name of
Milky Way, 136.
Webb, Rev. T. W 108, 109.
Whirlpool or Spiral Nebulae, 117.
Williams, J., 77.
Wolf-Rayet stars, 141.
Wordsworth, Quotations from, 100.
Wright, T., 134.
Y.
Young, C. A., 74,
- (P
oet), Quotations from, 98.
Z.
Zenith, 16.
Zodiac, Signs of, 37.
DATE DUE
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