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W. L. (William Larkin) Webb.

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tained by high temperature and hydrostatic pressure, but of late
years these views have been quite abandoned. The nebula are
much too rare for the exertion of any hydrostatic pressure. This
is proved from actual calculation in the solar system, by the fact
that if the sun be expanded to Neptune's orbit, as held in the
abandoned theory of Laplace, the density of the resulting nebula
is two hundred and sixty million times less than that of atmos-
pheric air at sea level, or thousands of times less than that of the
most perfect vacuum attainable.

A planetary nebula is therefore analogous to the infinite sys-
tem of comets revolving in all directions about the sun, except that
the comets are dense enough to render the whole nebula faintly
visible, which probably is not true of our system of comets as seen
from the other fixed stars. The vast extent and incredible rarity
of our system of comets and meteoric trains make them the
best known illustrations of what the average nebula really is.

Some nebulae contain certain self luminous gases, probably
shining at very low temperature by luminescence or electric excita-
tion, but most of the elements are non-luminous and give no
spectral indications of their presence.



UNPARALLELED DISCOVERIES OF T. J. J. SEE 191

XVII. THE PRINCIPAL CAUSE OF VARIABLE STARS TO BE
SOUGHT IN THE ACTION OF A RESISTING MEDIUM.

It is shown in my Researches on the Evolution of the Stellar
Systems, Vol. II, 1910, that, although quite unseen, planetary
systems really exist about the fixed stars which appear to be single
under the most refined observations of our greatest telescopes.
Our instruments reveal to us chiefly the bright companions at some
distance (visual double stars), or massive companions revolving
rapidly and in such close proximity as to become visible only by
the periodic shift of the spectral lines (spectroscopic binary stars).
In both classes of these objects the masses must be considerable,
while the planets attending the fixed stars revolve quite unseen
and forever beyond the reach of our most powerful instruments.

We know that planets attend the fixed stars for two reasons:
(1) They attend our sun, which is definitely known to have devel-
oped from a nebula. (2) The mode of formation which was opera-
tive when the planets began as small nuclei in the distance and
neared the center of the system under the attraction of gravitation
will necessarily have operated in the same way about the other
stars, which arose from nebulae under the very same laws. There-
fore the fixed stars generally have systems of planets, asteroids,
satellites, and comets; and the double stars are simply those
systems in which the smaller bodies have been so united as to pro-
duce large companions.

Now as all the stars have companions, and the resisting
medium exists everywhere, though with varying density, it follows
that those companions which plunge through considerable resist-
ance at perihelion will experience a variation in brightness. The
blazing up of the light will be comparatively rapid, the fall in bright-
ness more gradual, depending on the slower process of cooling.
These are the variable stars, of which more than a thousand are
known.

Some clusters are quite filled with variable stars, and it is
observed that their periods are very constant. This shows that



192 BRIEF BIOGRAPHY AND POPULAR ACCOUNT OF THE

these clusters are still supplied with ample nebulosity, and that
variation of such great regularity can depend on nothing but or-
bital motion for its regulating cause. Where the variation is irregu-
lar, one should suspect the presence of several disturbing bodies
the compound effects of which do not give regular periodicity. In
other cases there are phenomena of eclipses to be dwelt with, as in
the Algol and Beta Lyrse variables, but we need not dwell on these
details.

The important thing for us to observe is that the great cause
which has rounded up the orbits of our planets, enabled the planets
to capture their satellites, and given rise to the lunar craters, by
the destruction of millions of small bodies, is operative throughout
the universe; and it is therefore no wonder that many of the stars
are variable.

XVIII. NEW STARS DUE TO COLLISIONS WITH ATTENDANT

BODIES.

As all the fixed stars are attended by systems of planets and
comets, it will inevitably happen that collisions of disastrous
character between some of these bodies and their central suns will
occasionally occur.* My investigation of this question proves
that the Novae follow the Milky Way in just the proportion that
should occur if the outbursts depend simply on the thickness of
the stars on the back ground of the sky, so that wherever the stars
are numerous there the Novae will appear.

It was formerly supposed by some that the stars actually
come into collision with one another; but it is now realized that
such disasters are too rare to become noticeable, whereas collisions
with attendant planets or comets within the system must be infi-
nitely more frequent. Above all, as the Novae are of short dura-
tion, this fact points to conflagrations such as might follow from

* In this way probably arise the so-called stellar nebula*, which are correctly
distinguished from the planetary nebute. The former follow the Milky Way like
the Novx, and undoubtedly these two classes of objects are connected, though
this apparently has not been suspected heretofore.



UNPARALLELED DISCOVERIES OF T. J. J. SEE 193

the collision of a small mass, but not of one sun with another.
Accordingly it has come to be accepted that the new stars are due
to collisions with minor masses of the type of planets or very large
comets.

The theory that a comet might fall into a star which had
wasted in splendor was held by Newton, and thus our modern
view is merely an extension of that put forth by the immortal
author of the Principle in 1687.



XIX. CONNECTON ESTABLISHED BETWEEN ALL CLASSES OF

HEAVENLY BODIES.

i

The most significant result of the New Science of Cosmogony
as now developed is that these laws unite all the different classes
of the heavenly bodies into one continuous and unbroken whole.
Every star is a sun, attended by an infinite system of comets, and
by companions, whether the system has the form of a double star
or the more general type of a planetary system made up of nu-
merous small bodies. Whenever a system has a dominant body
like Jupiter, it has also a system of asteroids gathered within its
orbit, and a group of short period comets, such as our own Jupiter
has captured. The comets are destroyed, and the dust of their
disintegration serves to build up the masses of the planets.

In the transition of the asteroids over Jupiter's orbit, some
are captured and become satellites, which usually have a direct
revolution, but a lesser number may move retrograde, as actually
observed in the solar system. The collisions of captured particles
with the planets give these globes a direct rotation on their axes,
and establish obliquities like those observed in the planets revolv-
ing about our sun. The meteors, comets, asteroids, satellites and
smaller planets are consumed in building up the larger bodies of
the system. If a large companion revolves in an eccentric orbit,
most of the planetary bodies may be swallowed up in one of the
two large masses and thus lead to the development of a double
star. Should the stars be far apart there may arise a closer com-



194 BRIEF BIOGRAPHY AND POPULAR ACCOUNT OF THE

panion giving a triple or quadruple star, or one of the components
of a double star may become a spectroscopic binary. When a
nebula of vast extent is formed and develops by condensation at
many centers we have a cluster, with companions attending the
individual stars, and by revolving in the nebular resisting medium
giving us cluster variables, often with wonderful regularity of
period.

Collisions of large comets or planets with suns which have
wasted in splendor supply new or temporary stars, which blaze
forth wherever the stars are crowded on the background of the
sky, and therefore principally along the course of the Milky Way.
The dust expelled from the stars to form nebulae may take any of
the observed forms, and thus we have spiral, annular, elliptical,
planetary and irregular nebulae. Astronomers now recognize the
following classes of cosmical bodies: 1, single stars: 2, double
stars, including both visual and spectroscopic binaries; 3, multi-
ple stars; 4, clusters of stars; 5, star-clouds in the Milky Way;
6, the Milky Way itself, as a clustering stream of smaller systems
traversing the circuit of the heavens and here and there culminat-
ing in a perfect blaze from the intensity of the accumulated star-
light; 7, variable stars; 8, temporary stars; 9, planetary sys-
tems; 10, systems of satellites; 11, systems of asteroids; 12,
systems of comets; 13, spiral nebulae; 14, annular nebulae; 15,
elliptical nebulae; 16, planetary nebulae; 17, irregular nebulae;
18, diffuse nebulosity, often covering whole constellations; 19,
canopies of nebulae accumulating with maximum density near the
poles of the Milky Way; 20, two or more streams among the stars,
indicating that the observed order of the universe is slowly chang-
ing with the flight of ages.

It is obvious that a Science of Cosmogony which is founded
on a true basis should connect these different classes of bodies one
with another, and thus establish an unbroken continuity in the
observed order of Nature.

In the new edition of the Encyclopedia Britannica, under the
article Stars, it is pointed out by Mr. A. S. Eddington of the Royal



UNPARALLELED DISCOVERIES OF T. J. J. SEE 195

Observatory, Greenwich, that a fundamental contradiction arises
in our conceptions of cosmical evolution when, on the one hand,
we try to pass from systems of binary stars and planets, supposed
to be thrown off from the central nebula by the fluid fission pro-
cess of Poincare and Darwin to the star clusters, on the other,
which are supposed to be due to the aggregation of matter towards
centers, as imagined by Herschel. If Mr. Eddington had read
my papers of 1909 carefully, and above all the second volume of
my Researches, 1910, he would have seen that this long-standing
contradiction is now permanently removed, because I have proved
that the uniform Law of Nature is one of aggregation of matter
towards the large centers of attraction, while the only throwing
off that ever takes place is that of small particles expelled by the
action of repulsive forces. Mr. Eddington' s article doubtless
was prepared several years ago, but the failure to bring it up to
date in this and many other cases shows that the Britannica is
antiquated before it leaves the press, and it is not remarkable
therefore that it has so largely disappointed the scientific world.

From the foregoing theory it thus appears that we have a
simple and consistent explanation of all classes of the heavenly
bodies in their mutual relationship and distribution in space. The
harmony and order thus introduced into apparently confused and
extremely varied phenomena is the best proof that the laws now
recognized are the true Laws of Nature.



XX. PHILOSOPHICAL SIGNIFICANCE OF PLATO'S CELEBRATE
SAYING THAT THE DEITY ALWAYS GEOMETRIZES.

One of the most beautiful of these laws, as disclosed by the
New Science of Cosmogony, appeals especially to the geometer.
And as it has left a profound impress upon the geometry of the
heavens, we may conclude these remarks by a brief explanation
of it. We have seen that the nebulae are formed by the gathering
together of fine dust expelled from the stars, and that it eventu-
ally condenses into larger bodies. This unsymmetrical figure of



196 BRIEF BIOGRAPHY AND POPULAR ACCOUNT OF THE

a nebula often causes it to settle, under its own gravitation, and
develop into a spiral resembling the spiral of Archimedes. The
sun of the system develops at the center, while planets are formed
in the distance and made to approach the sun in orbits becoming
smaller and smaller and rounder and rounder, owing to the secular
effects of the nebular resisting medium. And the final outcome
is a planetary system of the beauty and order found about our
sun, the planets being attended by captured satellites and endowed
with axial rotation and small obliquity, often surrounded by atmos-
pheres and oceans, with all the conditions favorable for habitability.

This development represents one of the greatest and most
general laws of nature. Now if drawing ellipses and slowly trans-
forming them into circles for the orbits of planets, and thus estab-
lishing orderly systems out of the chaos of a spiral nebula may
be considered geometrizing, then Plato certainly was right when
he declared that the Deity always geometrizes o 0eos dct yew/AeVpct.

A sublimer truth than this probably never will be disclosed
to mortals. When we behold the starry heavens on a cloudless
night we may well recall the geometrizing of the Deity which is
always going! on for establishing the beauty and order of the
Cosmos.

U.S. Naval Observatory,

Mare Island, California,

August 7, 1911.



CHAPTER XIV.

1911.

DETERMINATION OF THE DEPTH OF THE MILKY WAY.*

By T. J. J. SEE.
(Read January 5, 1912.)

INTRODUCTORY REMARKS.



problem of determining the depth of the Milky Way, as
accurately as possible, is one which has now engaged my
attention for over twenty years, and I will therefore take
this occasion to bring together the results at which I have arrived,
partly because they are of high general interest, and partly because
the progress thus made will prove instructive as to the methods
which must be adopted for the measurement of the distances of
the most remote objects of the sidereal universe. Here we have
to deal with distances so immense that the method of annual
parallaxes, commonly used for the stars comparatively near the
sun, utterly fails; and recourse must be had to other methods
which will serve for the greatest distances to which our modern
giant telescopes can penetrate.

Alpha Centauri, the nearest of the fixed stars, was also the
first to be sucessfully measured for parallax, by Thomas Hender-
son, of the Cape of Good Hope, in 1831; but the work was not
reduced till January, 1839, and meanwhile Bessel had measured
the parallax of 61 Cygni in 1838 and promptly published the result
of his triumph. Of late years astronomers have given greatly
increased attention to the question of the distances of the stars
and systematic campaigns of the most laborious kind have been
carried on by Gill; Elkin and Chase, of Yale; Kapteyn, of Gronin-
gen; and Schlesinger, at the Yerkes Observatory, Chicago. Some

*Reprinted from Proceedings American Philosophical Society, Vol. li., 1912.



198 BRIEF BIOGRAPHY AND POPULAR ACCOUNT OF THE

three hundred and fifty stars have now been studied by the stand-
ard method of parallaxes, and for most of these objects, perhaps
about two hundred in number, fairly satisfactory data have been
deduced; but the method can be extended only to stars within
less than one hundred light-years of our sun, and is therefore very
limited in its applicability, owing to the small diameter of the earth's
orbit, and the insensible effects of the annual displacements result-
ing from the orbital motion of our planet. As nature herself has
fixed the limits of this method, astronomers have naturally cast
about for other methods of greater generality and have finally
developed processes of surprising power, of which an account will
be given in the present paper.

1. OUTLINE OF THE METHODS ADOPTED.

Among previous investigators who have occupied themselves
with the difficult problem of the profundity of the Milky Way the
first place will be universally assigned to the incomparable Sir
William Herschel, who extended his researches over many years,
and reached results which were for a time accepted, but have been
rejected for three quarters of a century, and yet are now proved to
be essentially correct. It is very remarkable and exceedingly
unfortunate that Herschel' s conclusions have been generally re-
jected by his son, Sir John Herschel, and other astronomers dur-
ing the past seventy-five years. But before discussing the circum-
stances which led to this outcome I shall recall the modern attempts
at the solution of the problem of determining distances in the
Milky Way.

After the spectroscope came into use, and Huggins had applied
Doeppler's principle to the motion in the line of sight (1868) it
was pointed out by Fox Talbot in 1871 (Brit. Assoc. Report, 1871,
p. 34, Pt. II.) that the possibility existed of determining the abso-
lute dimensions of the orbit of a pair of binary stars which had a
known angular dimension in the sky, and thus parallaxes might
be found of systems very remote from the earth. In 1890, while
a post-graduate student at the University of Berlin, I developed



UNPARALLELED DISCOVERIES OF T. J. J. SEE 199

this method still further, and showed how it could be used also to
test the accuracy of the law of universal gravitation in the stellar
systems. The spectroscopic method then outlined was brought
to more general form in 1895, and it at once occurred to me to point
out its use for measuring the distance of clusters in the Milky Way
(A.N. 3,323), as more certain than Herschel's method of star
gauges.

Our age is one of rapid improvement in all scientific processes
and during the past sixteen years naturally much progress has
been made in double-star astronomy, as well as in our knowledge
of nebulae and clusters. On looking more closely into the spectro-
scopic method, which in 1895 had been shown to be applicable to
objects 1,000 light-years from the sun, and might thus include all
suitable double-stars within this sphere, I became convinced that
while it is a great theoretical advance over the old method of par-
allaxes, it still is quite inadequate for finding the distances of the
most remote objects in the sidereal universe. Accordingly in 1909
I returned to the improvement of Herschel's method as the most
promising, for the determination of the distances of the most remote
objects. Here are the grounds for this decision:

1. It was noticed, as remarked by Burnham, that revolving
double stars are rare, if not unknown, in clusters, and among the
star-clouds of the Milky Way not because such systems are not
present in these masses of stars, but because they cannot be sepa-
rated, owing to the great distances at which these masses of stars
are removed from us.

2. When double stars cannot be clearly separated in the tele-
scope they cannot be used for parallax by the spectroscopic method;
and thus the spectroscopic method, while having a wider range of
application than the method of parallaxes, in something like the
ratio of the size of the double star orbit to that of the orbit of the
earth, is yet applicable only to stars within about 1,000 light-years
of our sun.

3. It will be shown below that the most remote stars are
separated from us by a distance of at least 1,000,000 light-years,



200 BRIEF BIOGRAPHY AND POPULAR ACCOUNT OF THE

and as this space is a thousand times that to which the spectro-
scopic method may be applied, it follows that there is no way of
fathoming these immense distances except by the improvement of
the method of Herschel.

And just as in my " Researches on the Evolution of the Stellar
Systems," Vol. II, 1910, p. 638, I had been able to adduce sub-
stantial grounds for returning to the vast distances calculated by
Herschel, so also during the past year I have been able to add to
the proof there brought forward, and will proceed to develop it
in the present paper.

2. HERSCHEL'S METHOD DEPENDING ON THE SPACE PENETRA-
TING POWER OF TELESCOPES.

In his celebrated star gauges Herschel employed a twenty-
foot reflector of eighteen inches aperture, and calculated the space-
penetrating power of such an instrument from the ratio of the
aperture of the telescope to that of the pupil of the eye. The com-
parative distance to which a star would have to be removed in order
that it may appear of the same brightness through the telescope
as it did before to the naked eye may thus be calculated. Herschel
found the power of this twenty- foot reflector to be seventy-five;
so that a star of sixth magnitude removed to seventy-five times its
present distance would therefore still be visible, as a star, in the
instrument.

Admitting such a sixth magnitude star to give only a hundredth
part of the light of the standard first magnitude star, it will follow
that the standard star could be seen as a sixth magnitude star at
ten times its present distance; and if we then multiply by the
space penetrating power, we get 750 as the distance to which the
standard star could be removed and still excite in the eye, when
viewed through the telescope, the same impression as a star of sixth
magnitude does to the naked eye. Thus if Alpha Centauri be
distant 4.5 light-years, it would be visible in Herschel's telescope
at a distance of 3,375 light-years. This is about the distance
ascribed to the remoter stars of the Milky Way by Newcomb and



UNPARALLELED DISCOVERIES OF T. J. J. SEE 201

many other modern writers; but of course it is much too small,
for the following reasons:

(a) Newcomb and other astronomers cite the possibility of
some of the stars being as much as 1,000,000 times brighter than
the average solar star, and in that case the star might be seen at
^1,000,000=1,000 times that distance, or 3,375,000 light-years,
with an instrument having a space penetrating power no greater
than that employed by Herschel, provided that no light is extin-
guished in its passage through space.

(b) If the telescope be more powerful than Herschel's 20-
foot reflector, the light gathered will be increased in the ratio of
x 2 /(18) 2 , where x = diameter of mirror; and for the 60-inch re-
flector at Pasadena, x = 60, over nine times as much light could
be gathered, or stars seen over three times as far away. Thus if
the stars have only about 10,000 times the luminosity of the sun,
they could still be seen with the Pasadena reflector at a distance
of over a million light-years. For 3,375 l.-y . X 3 X 100 = 1,012,500
light-years.

(c) The sensitiveness and accumulative effects of the photo-
graphic plate, will enable us to extend our sounding line still
further out into space by some three magnitudes, or four times the
distance; and thus with a modern 60-inch reflector we could photo-
graph stars at a distance of about four million light-years, if they
have 10,000 times the standard solar luminosity, and no light is
lost in space. How much light is really lost in space will be con-
sidered later, but it may be stated here that it probably is decidedly
less than was concluded by Struve.

3. INDEPENDENT CALCULATION OF THE DISTANCE OF THE
REMOTEST STARS OF THE HELIUM TYPE.

From the data given in Lick Observatory Bulletin No. 195,
we find that 225 helium stars employed by Campbell in his
line of sight work have an average visual magnitude of 4.14. Of
the four variables given in this Bulletin, we have used the
maximum brightness in three cases, because they are of the
algol type. In the case of u Herculis, we have used the mean



202 BRIEF BIOGRAPHY AND POPULAR ACCOUNT OF THE

magnitude, because the type of variable does not appear to be as
yet well established.

Here then we have 225 helium stars at an average distance of
about 540 light-years. For in Lick Observatory Bulletin No. 195,
p. 121, Campbell finds the 180 class B, or helium, stars to have an
average distance of 543 light-years, while in Publications of the
Astronomical Society of the Pacific for June- August, 1911, p. 159,
Professor Curtis gives 534 light-years as the average distance of
312 helium stars. The former distance for 180 stars being greater
than the latter distance for 312 stars, we may take 540 light-years
as the distance of the 225 helium stars here under discussion, the
average magnitude of which is 4.14.

If the average magnitude were decreased to 21.14, by removal
to 2,512 times their present distance, which would reduce the aver-
age brightness by 17 magnitudes, the distance of the stars would
be multiplied by 2,512, and become 1,356,480 light-years. This
is for the helium stars as they are, without any hypothesis as to
brightness, or as to the extinction of light in space, which will be
considered later.

The question will naturally be asked whether helium stars


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Online LibraryW. L. (William Larkin) WebbBrief biography and popular account of the unparalleled discoveries of T.J.J. See .. → online text (page 18 of 28)