The number of the _Quarterly Journal of Science_ for May, 1872,
contains some articles of considerable interest. The first is by
the indefatigable Mr. Proctor, on “Meteoric Astronomy,” in which
he embodies a clear and popular summary of the researches which
have earned for Signor Schiaparelli this year’s gold medal of the
Astronomical Society. Like all who venture upon a broad, bold effort of
scientific thought, extending at all into the regions of philosophical
theory, Schiaparelli has had to wait for recognition. A simple and
merely mechanical observation of a bare fact, barely and mechanically
recorded without the exercise of any other of the intellectual
faculties than the external senses and observing powers, is at once
received and duly honored by the scientific world; but any higher
effort is received at first indifferently, or sceptically, and is only
accepted after a period of probation, directly proportionate to its
philosophical magnitude and importance, and inversely proportionate to
the scientific status of the daring theorist.
At first sight this appears unjust, it looks like honoring the laborers
who merely make the bricks, and despising the architect who constructs
the edifice of philosophy from the materials they provide. Many a
disappointed dreamer, finding that his theory of the universe has not
been accepted, and that the expected honors have not been showered
upon him, has violently attacked the whole scientific community
as a contemptible gang of low-minded mechanical plodders, void of
imagination, blind to all poetic aspirations, and incapable of any
grand and comprehensive flight of intellect.
Had these impulsive gentlemen been previously subjected to the strict
discipline of inductive scientific training, their position and
opinions would have been very different. Their great theories would
either have had no existence, or have been much smaller, and they
would understand that philosophic caution is one of the characteristic
results of scientific training.
Simple facts, which can be immediately proved by simple experiments
and simple observations, are at once accepted, and their discoverers
duly honored, without any hesitation or delay, but the grander efforts
of generalization require careful thought and laborious scrutiny for
their verification, and therefore the acknowledgment of their merits is
necessarily delayed; but when it does arrive full justice is usually
done.
Thus Grove’s “Correlation of the Physical Forces,” the greatest
philosophical work on purely physical science of this generation, was
commenced in 1842, when its author occupied but a humble position at
the London Institution. The book was but little noticed for many years,
and, had Mr. Grove (now Sir William Grove) not been duly educated
by the discipline above referred to, he might have become a noisy
cantankerous martyr, one of those “ill-used men” who have been made
familiar to so many audiences by Mr. George Dawson.
Instead of this, he patiently waited, and, as we have lately seen, the
well-deserved honors have now been liberally awarded.
In a very few years hence we shall be able to say the same of the once
diabolical Darwin, and eight or nine other theorists, who must all be
content to take their trial and patiently await the verdict; the time
of waiting being of necessity proportionate to the magnitude of the
issue.
The theories of Schiaparelli, which, as Mr. Proctor says, “after the
usual term of doubt have so recently received the sanction of the
highest astronomical tribunal of Great Britain,” are not of so purely
speculative a character as to demand a very long “term of doubt.” They
are directly based on observations and mathematical calculations which
bring them under the domain of the recognized logic of mathematical
probability. Those who are specially interested in the modern progress
of astronomy should read this article in the _Quarterly Journal of
Science_, which is illustrated with the diagrams necessary for the
comprehension of the researches and reasoning of Schiaparelli and
others who have worked on the same ground.
I can only state the general results, which are that the meteors which
we see every year, more or less abundantly, on the nights of the 10th
and 11th of August, and which always appear to come from the same point
in the heavens, are then and thus visible because they form part of an
eccentric elliptical zone of meteoric bodies which girdle the domain of
the sun; and that our earth, in the course of its annual journey around
the sun, crosses and plunges more or less deeply into this ellipse of
small attendant bodies, which are supposed to be moving in regular
orbits around the sun.
Schiaparelli has compared the position, the direction, and the velocity
of motion of the August meteors with the orbit of the great comet of
1862, and infers that there is a close connection between them, so
close that the meteors may be regarded as a sort of trail which the
comet has left behind. He does not exactly say that they are detached
vertebræ of the comet’s tail, but suggests the possibility of their
original connection with its head.
Similar observations have been made upon the November meteoric showers,
which by similar reasoning, are associated with another comet; and
further yet, it is assumed upon analogy that other recognized meteor
systems, amounting to nearly two hundred in number, are in like manner
associated with other comets.
If these theories are sound, our diagrams and mental pictures of the
solar system must be materially modified. Besides the central sun, the
eight planets and the asteroids moving in their nearly circular orbits,
and some eccentric comets traveling in long ellipses, we must add a
countless multitude of small bodies clustered in elliptical rings, all
traveling together in the path marked by their containing girdle, and
following the lead of a streaming vaporous monster, their parent comet.
We must count such comets, and such rings filled with attendant
fragments, not merely by tens or hundreds, but by thousands and tens of
thousands, even by millions; the path of the earth being but a thread
in space, and yet a hundred or two are strung upon it.
In this article Mr. Proctor seems strongly disposed to return to
the theory which attributes solar heat and light to a bombardment
of meteors from without, and the solar corona and zodiacal light as
visible presentments of these meteors. Still, however, he clings to the
more recent explanation which regards the corona, the zodiacal light,
and the meteors as matter ejected from the sun by the same forces as
those producing the solar prominences. For my own part I shall not
be at all surprised if we find that, ere long, these two apparently
conflicting hypotheses are fully reconciled.
The progress of solar discovery has been so great since January, 1870,
when my ejection theory was published, that I may now carry it out
much further than I then dared, or was justified in daring to venture.
Actual measurement of the projectile forces displayed in some of the
larger prominences renders it not merely possible, but even very
probable, that some of the exceptionally great eruptive efforts of the
sun may be sufficiently powerful to eject solar material beyond the
reclaiming reach of his own gravitating power.
In such a case the banished matter must go on wandering through the
boundless profundity of space until it reaches the domain of some other
sun, which will clutch the fragment with its gravitating energies,
and turn its straight and ever onward course into the curved orbit.
Thus the truant morsel from our sun will become the subject of another
sun—a portion of another solar system.
What one sun may do, another and every other may do likewise, and, if
so, there must be a mutual bombardment, a ceaseless interchange of
matter between the countless suns of the universe. This is a startling
view of our cosmical relations, but we are driving rapidly towards a
general recognition of it.
The November star showers have perpetrated some irregularities this
year. They have been very unpunctual, and have not come from their
right place. We have heard something from Italy, but not the tidings of
the Leonides that were expected. Instead of the great display of the
month occurring on the 13th and 14th, it was seen on the 27th. We have
accounts from different parts of England, Ireland, Scotland, and Wales,
also from Italy, Greece, Egypt, etc.
Mr. Slinto, in a letter to the _Times_, estimates the number seen at
Suez as reaching at least 30,000, while in Italy and Athens about 200
per minute were observed. They were not, however, the Leonides, that
is, they did not radiate from a point in the constellation Leo, but
from the region of Andromeda. Therefore they were distinct from that
system of small wanderers usually designated the “November meteors,”
were not connected with Tempel’s comet (comet 1, 1866), but belong to
quite another set.
The question now discussed by astronomers is whether they are connected
with any other comet, and, if so, with which comet?
In the “Monthly Notices” of the Royal Astronomical Society, published
October 24th last, is a very interesting paper by Professor Herschel,
on “Observations of Meteor Showers,” supposed to be connected with
“Biela’s comet,” in which he recommends that “a watch should be kept
during the last week in November and the first week in December,”
in order to verify “the ingenious suggestions of Dr. Weiss,” which,
popularly stated, amount to this, viz., that a meteoric cloud is
revolving in the same orbit as Biela’s comet, and that in 1772 the
earth dashed through this meteoric orbit on December 10th. In 1826 it
did the same, on December 4th; in 1852 the earth passed through the
node on November 28th, and there are reasons for expecting a repetition
at about the same date in 1872.
The magnificent display of the 27th has afforded an important
verification of these anticipations, which become especially
interesting in connection with the curious history of Biela’s comet,
which receives its name from M. Biela, of Josephstadt, who observed it
in 1826, calculated its orbit, and considered it identical with the
comets of 1772, 1805, etc. It travels in a long eccentric ellipse, and
completes its orbit in 2410 days—about 6¾ years. It appeared again, as
predicted, in 1832 and 1846.
Its orbit very nearly intersects that of the earth, and thus affords
a remote possibility of that sort of collision which has excited so
much terror in the minds of many people, but which an enthusiastic
astronomer of the present generation would anticipate with something
like the sensational interest which stirs the soul of a London
street-boy when he is madly struggling to keep pace with a fire-engine.
The calculations for 1832 showed that this comet should cross the
earth’s orbit a little before the time of the earth’s arrival at the
same place; but as such a comet, traveling in such an orbit, is liable
to possible retardations, the calculations could only be approximately
accurate, and thus the sensational astronomer was not altogether
without hope. This time, however, he was disappointed; the comet was
punctual, and crossed the critical node about a month before the earth
reached it.
As though to compensate for this disappointment, the comet at its next
appearance exhibited some entirely new phenomena. It split itself into
two comets, in such a manner that the performance was visible to the
telescopic observer. Both of these comets had nuclei and short tails,
and they alternately varied in brightness, sometimes one, then the
other, having the advantage. They traveled on at a distance of about
156,000 miles from each other, with parallel tails, and with a sort
of friendly communication in the form of a faint arc of light, which
extended as a kind of bridge, from one to the other. Besides this, the
one which was first the brighter, then the fainter, and finally the
brighter again, threw out two additional tails, one of which extended
lovingly towards its companion.
The time of return in 1852 was of course anxiously expected by
astronomers, and careful watch was kept for the wanderers. They came
again at the calculated time, still separated as before.
They were again due in 1859, in 1866, and, finally, at about the end of
last November, or the beginning of the present month. Though eagerly
looked for by astronomers in all parts of the civilized world, they
have been seen no more since 1852.
What, then, has become of them? Have they further subdivided? Have they
crumbled into meteoric dust? Have they blazed or boiled into thin air?
or have they been dragged by some interfering gravitation into another
orbit? The last supposition is the most improbable, as none of the
visible inhabitants of space have come near enough to disturb them.
The possibility of a dissolution into smaller fragments is suggested
by the fact that, instead of the original single comet, or the two
fragments, meteoric showers have fallen towards the earth at the time
when it has crossed the orbit of the original comet, and these showers
have radiated from that part of the heavens in which the comet should
have appeared. Such was the case with the magnificent display of
November 27th, and astronomers are inclining more and more to the idea
that comets and meteors have a common origin—the meteors are little
comets, or comets are big meteors.
In the latest of the “Monthly Notices,” of the Royal Astronomical
Society, published last week, is a paper by Mr. Proctor, in which he
expands the theory expounded three years ago by an author whom your
correspondent’s modesty prevents him from naming, viz., that the larger
planets—Jupiter, Saturn, Uranus, and Neptune—are minor suns, ejecting
meteoric matter from them by the operation of forces similar to those
producing the solar prominences.
Mr. Proctor subjects this bold hypothesis to mathematical examination,
and finds that the orbit of Tempel’s comet and its companion meteors
correspond to that which would result from such an eruption occurring
on the planet Uranus. An eruptive force effecting a velocity of about
thirteen miles per second, which is vastly smaller than the actually
measured velocity of the matter of the solar eruptions, would be
sufficient to thrust such meteoric or cometary matter beyond the
reclaiming reach of the gravitation of Uranus, and hand it over to the
sun, to make just such an orbit as that of Tempel’s comet and the
Leonides meteors.
He shows that other comets and meteoric zones are similarly allied to
other planets, and thus it may be that the falling stars and comets
are fragments of Jupiter, Saturn, Uranus, or Neptune. Verily, if an
astronomer of the last generation were to start up among us now, he
would be astounded at modern presumption.
The star shower of November 27th, and its connection with Biela’s
broken and lost comet, referred to in my last letter, are still
subjects of research and speculation. On November 30th Professor
Klinkerfues sent to Mr. Pogson, of the Madras Observatory, the
following startling telegram: “Biela touched earth on 27th. Search near
Theta Centauri.”
Mr. Pogson searched accordingly from comet-rise to sunrise on the two
following mornings, but in vain; for even in India they have had cloudy
weather of late. On the third day, however, he had “better luck,” saw
something like a comet through an opening between clouds, and on the
following days was enabled to deliberately verify this observation and
determine the position and some elements of the motion of the comet,
which displayed a bright nucleus, and faint but distinct tail.
This discovery is rather remarkable in connection with the theoretical
anticipation of Professor Klinkerfues; but the conclusion directly
suggested is by no means admitted by astronomers. Some, have supposed
that it is not the primary Biela, but the secondary comet, or offshoot,
which grazed the earth, and was seen by Mr. Pogson; others that it was
neither the body, the envelope, nor the tail of either of the comets
which formed the star shower, but that the meteors of November 27th
were merely a trail which the comet left behind.
A multitude of letters were read at the last and previous meeting of
the Astronomical Society, in which the writers described the details
of their own observations. As these letters came from nearly all parts
of the world, the data have an unusual degree of completeness, and
show very strikingly the value of the work of amateur astronomical
observers.
By the collation and comparison of these, important inductions are
obtainable. Thus Professor A. S. Herschel concludes that the earth
passed through seven strata of meteoric bodies, having each a thickness
of about 50,000 miles—in all about 350,000 miles. As the diameter
of the visible nebulosity of Biela’s comet was but 40,000 miles
when nearest the earth in 1832, the great thickness of these strata
indicates something beyond the comet itself.
Besides this, Mr. Hind’s calculation for the return of the primary
comet shows that on November 27th it was 250 millions of miles from the
earth.
Those, however, who are determined to enjoy the sensation of supposing
that they really have been brushed by the tail of a comet, still have
the secondary comet to fall back upon. This, as already described, was
broken off the original, from which it was seen gradually to diverge,
but was still linked to it by an arch of nebulous matter.
If this divergence has continued, it must now be far
distant—sufficiently far to afford me an opportunity of safely adding
another to the numerous speculations, viz., that we may, on November
27th, have plunged obliquely through this connecting arm of nebulous
matter, which was seen stretching between the parent comet and its
offshoot. The actual position of the meteoric strata above referred to
is quite consistent with the hypothesis.