another which appears, for us, to be insoluble because it brings us
face to face with infinity itself. We are familiar enough with
eternity, or, let us say, the millions or hundreds of millions of years
which geologists tell us must have passed while the crust of the earth
was assuming its present form, our mountains being built, our rocks
consolidated, and successive orders of animals coming and going.
Hundreds of millions of years is indeed a long time, and yet, when we
contemplate the changes supposed to have taken place during that time,
we do not look out on eternity itself, which is veiled from our sight,
as it were, by the unending succession of changes that mark the
progress of time. But in the motions of the stars we are brought face
to face with eternity and infinity, covered by no veil whatever. It
would be bold to speak dogmatically on a subject where the springs of
being are so far hidden from mortal eyes as in the depths of the
universe. But, without declaring its positive certainty, it must be
said that the conclusion seems unavoidable that a number of stars are
moving with a speed such that the attraction of all the bodies of the
universe could never stop them. One such case is that of Arcturus, the
bright reddish star familiar to mankind since the days of Job, and
visible near the zenith on the clear evenings of May and June. Yet
another case is that of a star known in astronomical nomenclature as
1830 Groombridge, which exceeds all others in its angular proper motion
as seen from the earth. We should naturally suppose that it seems to
move so fast because it is near us. But the best measurements of its
parallax seem to show that it can scarcely be less than two million
times the distance of the earth from the sun, while it may be much
greater. Accepting this result, its velocity cannot be much less than
two hundred miles per second, and may be much more. With this speed it
would make the circuit of our globe in two minutes, and had it gone
round and round in our latitudes we should have seen it fly past us a
number of times since I commenced this discourse. It would make the
journey from the earth to the sun in five days. If it is now near the
centre of our universe it would probably reach its confines in a
million of years. So far as our knowledge goes, there is no force in
nature which would ever have set it in motion and no force which can
ever stop it. What, then, was the history of this star, and, if there
are planets circulating around, what the experience of beings who may
have lived on those planets during the ages which geologists and
naturalists assure us our earth has existed? Was there a period when
they saw at night only a black and starless heaven? Was there a time
when in that heaven a small faint patch of light began gradually to
appear? Did that patch of light grow larger and larger as million after
million of years elapsed? Did it at last fill the heavens and break up
into constellations as we now see them? As millions more of years
elapse will the constellations gather together in the opposite quarter
and gradually diminish to a patch of light as the star pursues its
irresistible course of two hundred miles per second through the
wilderness of space, leaving our universe farther and farther behind
it, until it is lost in the distance? If the conceptions of modern
science are to be considered as good for all time--a point on which I
confess to a large measure of scepticism--then these questions must be
answered in the affirmative.
The problems of which I have so far spoken are those of what may be
called the older astronomy. If I apply this title it is because that
branch of the science to which the spectroscope has given birth is
often called the new astronomy. It is commonly to be expected that a
new and vigorous form of scientific research will supersede that which
is hoary with antiquity. But I am not willing to admit that such is the
case with the old astronomy, if old we may call it. It is more pregnant
with future discoveries today than it ever has been, and it is more
disposed to welcome the spectroscope as a useful handmaid, which may
help it on to new fields, than it is to give way to it. How useful it
may thus become has been recently shown by a Dutch astronomer, who
finds that the stars having one type of spectrum belong mostly to the
Milky Way, and are farther from us than the others.
In the field of the newer astronomy perhaps the most interesting work
is that associated with comets. It must be confessed, however, that the
spectroscope has rather increased than diminished the mystery which, in
some respects, surrounds the constitution of these bodies. The older
astronomy has satisfactorily accounted for their appearance, and we
might also say for their origin and their end, so far as questions of
origin can come into the domain of science. It is now known that comets
are not wanderers through the celestial spaces from star to star, but
must always have belonged to our system. But their orbits are so very
elongated that thousands, or even hundreds of thousands, of years are
required for a revolution. Sometimes, however, a comet passing near to
Jupiter is so fascinated by that planet that, in its vain attempts to
follow it, it loses so much of its primitive velocity as to circulate
around the sun in a period of a few years, and thus to become,
apparently, a new member of our system. If the orbit of such a comet,
or in fact of any comet, chances to intersect that of the earth, the
latter in passing the point of intersection encounters minute particles
which cause a meteoric shower.
But all this does not tell us much about the nature and make-up of a
comet. Does it consist of nothing but isolated particles, or is there a
solid nucleus, the attraction of which tends to keep the mass together?
No one yet knows. The spectroscope, if we interpret its indications in
the usual way, tells us that a comet is simply a mass of hydrocarbon
vapor, shining by its own light. But there must be something wrong in
this interpretation. That the light is reflected sunlight seems to
follow necessarily from the increased brilliancy of the comet as it
approaches the sun and its disappearance as it passes away.
Great attention has recently been bestowed upon the physical
constitution of the planets and the changes which the surfaces of those
bodies may undergo. In this department of research we must feel
gratified by the energy of our countrymen who have entered upon it.
Should I seek to even mention all the results thus made known I might
be stepping on dangerous ground, as many questions are still unsettled.
While every astronomer has entertained the highest admiration for the
energy and enthusiasm shown by Mr. Percival Lowell in founding an
observatory in regions where the planets can be studied under the most
favorable conditions, they cannot lose sight of the fact that the
ablest and most experienced observers are liable to error when they
attempt to delineate the features of a body 50,000,000 or 100,000,000
miles away through such a disturbing medium as our atmosphere. Even on
such a subject as the canals of Mars doubts may still be felt. That
certain markings to which Schiaparelli gave the name of canals exist,
few will question. But it may be questioned whether these markings are
the fine, sharp, uniform lines found on Schiaparelli's map and
delineated in Lowell's beautiful book. It is certainly curious that
Barnard at Mount Hamilton, with the most powerful instrument and under
the most favorable circumstances, does not see these markings as canals.
I can only mention among the problems of the spectroscope the elegant
and remarkable solution of the mystery surrounding the rings of Saturn,
which has been effected by Keeler at Allegheny. That these rings could
not be solid has long been a conclusion of the laws of mechanics, but
Keeler was the first to show that they really consist of separate
particles, because the inner portions revolve more rapidly than the
outer.
The question of the atmosphere of Mars has also received an important
advance by the work of Campbell at Mount Hamilton. Although it is not
proved that Mars has no atmosphere, for the existence of some
atmosphere can scarcely be doubted, yet the Mount Hamilton astronomer
seems to have shown, with great conclusiveness, that it is so rare as
not to produce any sensible absorption of the solar rays.
I have left an important subject for the close. It belongs entirely to
the older astronomy, and it is one with which I am glad to say this
observatory is expected to especially concern itself. I refer to the
question of the variation of latitudes, that singular phenomenon
scarcely suspected ten years ago, but brought out by observations in
Germany during the past eight years, and reduced to law with such
brilliant success by our own Chandler. The north pole is not a fixed
point on the earth's surface, but moves around in rather an irregular
way. True, the motion is small; a circle of sixty feet in diameter will
include the pole in its widest range. This is a very small matter so
far as the interests of daily life are concerned; but it is very
important to the astronomer. It is not simply a motion of the pole of
the earth, but a wobbling of the solid earth itself. No one knows what
conclusions of importance to our race may yet follow from a study of
the stupendous forces necessary to produce even this slight motion.
The director of this new observatory has already distinguished himself
in the delicate and difficult work of investigating this motion, and I
am glad to know that he is continuing the work here with one of the
finest instruments ever used for the purpose, a splendid product of
American mechanical genius. I can assure you that astronomers the world
over will look with the greatest interest for Professor Doolittle's
success in the arduous task he has undertaken.
There is one question connected with these studies of the universe on
which I have not touched, and which is, nevertheless, of transcendent
interest. What sort of life, spiritual and intellectual, exists in
distant worlds? We cannot for a moment suppose that our little planet
is the only one throughout the whole universe on which may be found the
fruits of civilization, family affection, friendship, the desire to
penetrate the mysteries of creation. And yet this question is not
to-day a problem of astronomy, nor can we see any prospect that it ever
will be, for the simple reason that science affords us no hope of an
answer to any question that we may send through the fathomless abyss.
When the spectroscope was in its infancy it was suggested that possibly
some difference might be found in the rays reflected from living
matter, especially from vegetation, that might enable us to distinguish
them from rays reflected by matter not endowed with life. But this hope
has not been realized, nor does it seem possible to realize it. The
astronomer cannot afford to waste his energies on hopeless speculation
about matters of which he cannot learn anything, and he therefore
leaves this question of the plurality of worlds to others who are as
competent to discuss it as he is. All he can tell the world is:
He who through vast immensity can pierce,
See worlds on worlds compose one universe;
Observe how system into system runs,
What other planets circle other suns,
What varied being peoples every star,
May tell why Heaven has made us as we are.
XVIII
ASPECTS OF AMERICAN ASTRONOMY
[Footnote: Address delivered at the University of Chicago, October 22,
1897, in connection with the dedication of the Yerkes Observatory.
Printed in the Astro physical Journal. November, 1897.]
The University of Chicago yesterday accepted one of the most munificent
gifts ever made for the promotion of any single science, and with
appropriate ceremonies dedicated it to the increase of our knowledge of
the heavenly bodies.
The president of your university has done me the honor of inviting me
to supplement what was said on that occasion by some remarks of a more
general nature suggested by the celebration. One is naturally disposed
to say first what is uppermost in his mind. At the present moment this
will naturally be the general impression made by what has been seen and
heard. The ceremonies were attended, not only by a remarkable
delegation of citizens, but by a number of visiting astronomers which
seems large when we consider that the profession itself is not at all
numerous in any country. As one of these, your guests, I am sure that I
give expression only to their unanimous sentiment in saying that we
have been extremely gratified in many ways by all that we have seen and
heard. The mere fact of so munificent a gift to science cannot but
excite universal admiration. We knew well enough that it was nothing
more than might have been expected from the public spirit of this great
West; but the first view of a towering snowpeak is none the less
impressive because you have learned in your geography how many feet
high it is, and great acts are none the less admirable because they
correspond to what you have heard and read, and might therefore be led
to expect.
The next gratifying feature is the great public interest excited by the
occasion. That the opening of a purely scientific institution should
have led so large an assemblage of citizens to devote an entire day,
including a long journey by rail, to the celebration of yesterday is
something most suggestive from its unfamiliarity. A great many
scientific establishments have been inaugurated during the last
half-century, but if on any such occasion so large a body of citizens
has gone so great a distance to take part in the inauguration, the fact
has at the moment escaped my mind.
That the interest thus shown is not confined to the hundreds of
attendants, but must be shared by your great public, is shown by the
unfailing barometer of journalism. Here we have a field in which the
non-survival of the unfit is the rule in its most ruthless form. The
journals that we see and read are merely the fortunate few of a
countless number, dead and forgotten, that did not know what the public
wanted to read about. The eagerness shown by the representatives of
your press in recording everything your guests would say was
accomplished by an enterprise in making known everything that occurred,
and, in case of an emergency requiring a heroic measure, what did NOT
occur, showing that smart journalists of the East must have learned
their trade, or at least breathed their inspiration, in these regions.
I think it was some twenty years since I told a European friend that
the eighth wonder of the world was a Chicago daily newspaper. Since
that time the course of journalistic enterprise has been in the reverse
direction to that of the course of empire, eastward instead of westward.
It has been sometimes said--wrongfully, I think--that scientific men
form a mutual admiration society. One feature of the occasion made me
feel that we, your guests, ought then and there to have organized such
a society and forthwith proceeded to business. This feature consisted
in the conferences on almost every branch of astronomy by which the
celebration of yesterday was preceded. The fact that beyond the
acceptance of a graceful compliment I contributed nothing to these
conferences relieves me from the charge of bias or self-assertion in
saying that they gave me a new and most inspiring view of the energy
now being expended in research by the younger generation of
astronomers. All the experience of the past leads us to believe that
this energy will reap the reward which nature always bestows upon those
who seek her acquaintance from unselfish motives. In one way it might
appear that little was to be learned from a meeting like that of the
present week. Each astronomer may know by publications pertaining to
the science what all the others are doing. But knowledge obtained in
this way has a sort of abstractness about it a little like our
knowledge of the progress of civilization in Japan, or of the great
extent of the Australian continent. It was, therefore, a most happy
thought on the part of your authorities to bring together the largest
possible number of visiting astronomers from Europe, as well as
America, in order that each might see, through the attrition of
personal contact, what progress the others were making in their
researches. To the visitors at least I am sure that the result of this
meeting has been extremely gratifying. They earnestly hope, one and
all, that the callers of the conference will not themselves be more
disappointed in its results; that, however little they may have
actually to learn of methods and results, they will feel stimulated to
well-directed efforts and find themselves inspired by thoughts which,
however familiar, will now be more easily worked out.
We may pass from the aspects of the case as seen by the strictly
professional class to those general aspects fitted to excite the
attention of the great public. From the point of view of the latter it
may well appear that the most striking feature of the celebration is
the great amount of effort which is shown to be devoted to the
cultivation of a field quite outside the ordinary range of human
interests. The workers whom we see around us are only a detachment from
an army of investigators who, in many parts of the world, are seeking
to explore the mysteries of creation. Why so great an expenditure of
energy? Certainly not to gain wealth, for astronomy is perhaps the one
field of scientific work which, in our expressive modern phrase, "has
no money in it." It is true that the great practical use of
astronomical science to the country and the world in affording us the
means of determining positions on land and at sea is frequently pointed
out. It is said that an Astronomer Royal of England once calculated
that every meridian observation of the moon made at Greenwich was worth
a pound sterling, on account of the help it would afford to the
navigation of the ocean. An accurate map of the United States cannot be
constructed without astronomical observations at numerous points
scattered over the whole country, aided by data which great
observatories have been accumulating for more than a century, and must
continue to accumulate in the future.
But neither the measurement of the earth, the making of maps, nor the
aid of the navigator is the main object which the astronomers of to-day
have in view. If they do not quite share the sentiment of that eminent
mathematician, who is said to have thanked God that his science was one
which could not be prostituted to any useful purpose, they still know
well that to keep utilitarian objects in view would only prove &
handicap on their efforts. Consequently they never ask in what way
their science is going to benefit mankind. As the great captain of
industry is moved by the love of wealth, and the political leader by
the love of power over men, so the astronomer is moved by the love of
knowledge for its own sake, and not for the sake of its useful
applications. Yet he is proud to know that his science has been worth
more to mankind than it has cost. He does not value its results merely
as a means of crossing the ocean or mapping the country, for he feels
that man does not live by bread alone. If it is not more than bread to
know the place we occupy in the universe, it is certainly something
which we should place not far behind the means of subsistence. That we
now look upon a comet as something very interesting, of which the sight
affords us a pleasure unmixed with fear of war, pestilence, or other
calamity, and of which we therefore wish the return, is a gain we
cannot measure by money. In all ages astronomy has been an index to the
civilization of the people who cultivated it. It has been crude or
exact, enlightened or mingled with superstition, according to the
current mode of thought. When once men understand the relation of the
planet on which they dwell to the universe at large, superstition is
doomed to speedy extinction. This alone is an object worth more than
money.
Astronomy may fairly claim to be that science which transcends all
others in its demands upon the practical application of our reasoning
powers. Look at the stars that stud the heavens on a clear evening.
What more hopeless problem to one confined to earth than that of
determining their varying distances, their motions, and their physical
constitution? Everything on earth we can handle and investigate. But
how investigate that which is ever beyond our reach, on which we can
never make an experiment? On certain occasions we see the moon pass in
front of the sun and hide it from our eyes. To an observer a few miles
away the sun was not entirely hidden, for the shadow of the moon in a
total eclipse is rarely one hundred miles wide. On another continent no
eclipse at all may have been visible. Who shall take a map of the world
and mark upon it the line on which the moon's shadow will travel during
some eclipse a hundred years hence? Who shall map out the orbits of the
heavenly bodies as they are going to appear in a hundred thousand
years? How shall we ever know of what chemical elements the sun and the
stars are made? All this has been done, but not by the intellect of any
one man. The road to the stars has been opened only by the efforts of
many generations of mathematicians and observers, each of whom began
where his predecessor had left off.
We have reached a stage where we know much of the heavenly bodies. We
have mapped out our solar system with great precision. But how with
that great universe of millions of stars in which our solar system is
only a speck of star-dust, a speck which a traveller through the wilds
of space might pass a hundred times without notice? We have learned
much about this universe, though our knowledge of it is still dim. We
see it as a traveller on a mountain-top sees a distant city in a cloud
of mist, by a few specks of glimmering light from steeples or roofs. We
want to know more about it, its origin and its destiny; its limits in
time and space, if it has any; what function it serves in the universal
economy. The journey is long, yet we want, in knowledge at least, to
make it. Hence we build observatories and train observers and
investigators. Slow, indeed, is progress in the solution of the
greatest of problems, when measured by what we want to know. Some
questions may require centuries, others thousands of years for their
answer. And yet never was progress more rapid than during our time. In
some directions our astronomers of to-day are out of sight of those of
fifty years ago; we are even gaining heights which twenty years ago
looked hopeless. Never before had the astronomer so much work--good,
hard, yet hopeful work--before him as to-day. He who is leaving the
stage feels that he has only begun and must leave his successors with
more to do than his predecessors left him.
To us an interesting feature of this progress is the part taken in it
by our own country. The science of our day, it is true, is of no
country. Yet we very appropriately speak of American science from the
fact that our traditional reputation has not been that of a people
deeply interested in the higher branches of intellectual work. Men yet
living can remember when in the eyes of the universal church of
learning, all cisatlantic countries, our own included, were partes
infidelium.
Yet American astronomy is not entirely of our generation. In the middle
of the last century Professor Winthrop, of Harvard, was an industrious
observer of eclipses and kindred phenomena, whose work was recorded in
the transactions of learned societies. But the greatest astronomical
activity during our colonial period was that called out by the transit
of Venus in 1769, which was visible in this country. A committee of the
American Philosophical Society, at Philadelphia, organized an excellent
system of observations, which we now know to have been fully as
successful, perhaps more so, than the majority of those made on other
continents, owing mainly to the advantages of air and climate. Among
the observers was the celebrated Rittenhouse, to whom is due the
distinction of having been the first American astronomer whose work has
an important place in the history of the science. In addition to the
observations which he has left us, he was the first inventor or
proposer of the collimating telescope, an instrument which has become
almost a necessity wherever accurate observations are made. The fact
that the subsequent invention by Bessel may have been independent does
not detract from the merits of either.
Shortly after the transit of Venus, which I have mentioned, the war of
the Revolution commenced. The generation which carried on that war and
the following one, which framed our Constitution and laid the bases of
our political institutions, were naturally too much occupied with these
great problems to pay much attention to pure science. While the great
mathematical astronomers of Europe were laying the foundation of
celestial mechanics their writings were a sealed book to every one on
this side of the Atlantic, and so remained until Bowditch appeared,
early in the present century. His translation of the Mecanique Celeste
made an epoch in American science by bringing the great work of Laplace
down to the reach of the best American students of his time.
American astronomers must always honor the names of Rittenhouse and
Bowditch. And yet in one respect their work was disappointing of
results. Neither of them was the founder of a school. Rittenhouse left
no successor to carry on his work. The help which Bowditch afforded his
generation was invaluable to isolated students who, here and there,
dived alone and unaided into the mysteries of the celestial motions.
His work was not mainly in the field of observational astronomy, and
therefore did not materially influence that branch of science. In 1832
Professor Airy, afterwards Astronomer Royal of England, made a report
to the British Association on the condition of practical astronomy in
various countries. In this report he remarked that he was unable to say
anything about American astronomy because, so far as he knew, no public
observatory existed in the United States.
William C. Bond, afterwards famous as the first director of the Harvard
Observatory, was at that time making observations with a small
telescope, first near Boston and afterwards at Cambridge. But with so
meagre an outfit his establishment could scarcely lay claim to being an
astronomical observatory, and it was not surprising if Airy did not
know anything of his modest efforts.
If at this time Professor Airy had extended his investigations into yet
another field, with a view of determining the prospects for a great
city at the site of Fort Dearborn, on the southern shore of Lake
Michigan, he would have seen as little prospect of civic growth in that
region as of a great development of astronomy in the United States at
large. A plat of the proposed town of Chicago had been prepared two
years before, when the place contained perhaps half a dozen families.
In the same month in which Professor Airy made his report, August,
1832, the people of the place, then numbering twenty-eight voters,
decided to become incorporated, and selected five trustees to carry on
their government.