.093 ºf 5
OUR FRIENDS, THE ENEMY is
A DISCUSSION BEARING ON SCIENTIFIC ETHICS,
B 530624" WITH CONCRETE ILLUSTRATIONS
fºr ºf .
. . . . .º.º.
~ . . . . . *
* , ;
;
3.
* .
3.
t
#.
f
f
}
\
*\
#
--..
:
;
MARS AS THE ABODE OF LIFE. By PROF. ELIOT BLACKWELDER. SciENCE,
April 23, 1909, pp. 659–661.
TAIR PLAY AND TOLERATION IN SCIENCE. By DR. T. J. J. SEE. SciENCE,
May 28, 1909, pp. 858–860. *
r FAIR PLAY AND TOLERATION IN CRITICISM. By PROF. Joseph BARRELL. .
SciENCE, July 2, 1909, pp. 21–23.
REMARKS ON RECENT CONTRIBUTIONS TO COSMOGONY. By DR. F. R.
- MoULTON. ScIENCE, July 23, 1909, pp. 113–117. is
MARS AS THE ABODE OF LIFE. By DR. PERCIvaL Lowell. SCIENCE, September
10, 1909, pp. 338-340.
GEOLOGY AND COSMOGONY. By DR. T. J. J. SEE. Science, October 8, 1909,
pp. 479–480.
A REPLY TO DR. LOWELL. By PROF. F. R. MoULTON. SCIENCE, November 5,
1909, pp. 639-641.
THE DEVELOPMENT OF THE PLANETESIMAL HYPOTHESIS. By DRs. T.
C. CHAMBERLIN and F. R. MoULTON. ScIENCE, November 5, 1909, pp. 642–645.
~,
[Reprinted from Sorence, N. S., Vol. XXIX., No. 747, Pages 659–661, April 23, 1909;
No. 752, Pages 858–860, May 28; Volume XXX., No. 757, Pages 21–23, July 2,
1909; No. 760, Pages 113–117, July 23; No. 767, Pages 388-340,
September 10; No. 771, Pages 479–480, October 8; No. 775,
Pages 639-641; Pages 642–645, November 5 ..] …



PICUUIIITSILIIIIIIIIIIIIIIIIIIIIIIIIIIATIŪRĀTĪTĪĶIIIIIIIIIII
Eºs •№ • ！C C C C C （， ， Ō Ō Ō Ō Ō Ō Ō ， ， ， ∈
|
|||||||
|U||
||||||||||||||
|
iiiiiiiiiiiſſiſſiſſiſſiſſiſſiſi
Truminimiſſiºn iTun
Illutil
Eºfºrºlºnitºr
|--
EC-
*-ș -
ëſ§§
§§§

[Reprinted from Sorence, N. S., Vol. XXIX., No. 747, Pages 659–661, April 23, 1909;
No. 752, Pages 858–860, May 28, 1909; Volume XXX., No. 757, Pages 21–23, July
2, 1909; No. 760, Pages 113–117, July 23, 1909; No. 767, Pages, 838–340,
September 10, 1909; No. 771, Pages 479–480, October 8, 1909;
No. 775, Pages 689-641; Pages 642–645, November 5, 1909.]
agº.
OUR FRIENDS, THE ENEMY
MARS AS THE ABODE OF LIFE."
ALTHOUGH it is improbable that these lines
will be read by more than a small proportion
of those who have seen or heard of Mr. Perci-
val Lowell’s “Mars as the Abode of Life,” it
seems worth while to point out to the scien-
tific workers of the country the gross errors
which this book is propagating. In this I
shall confine myself to geological matters,
leaving the astronomical and other questions
to those who have special acquaintance with
such things. It is not surprising that Mr.
Lowell, an astronomer, should have only a
layman’s knowledge of geology; but that he
should attempt to discuss critically the more
difficult problems of that science, without, as
his words show, any understanding of the great
recent progress in geology, is astonishing and
disastrous. One can not but recall the adage
that “fools rush in where angels fear to
tread.”
Mr. Lowell is an implicit believer in the
Laplacian theory of planetary evolution, a
hypothesis now on the defensive, to say the
least, and utterly abandoned by some of our
best cosmogonists.
On an adjacent page he says that the min-
erals of the metamorphic rocks “show by their
crystalline form that they cooled from a once
molten state.” The fallacy in this statement
is evident to the average college student of
* A series of lectures delivered before the Lowell
Institute, Boston; later published in the Century
Magazine, 1908; and subsequently issued as a
volume by The Macmillan Company, New York,
1908. -
, r---,
*
geology or chemistry. Metamorphic rocks are
produced by processes which involve more or
less pressure and heat, but not melting.
Turning to consider the evolution of life
on the earth, the author tells us that “the
geologic record proves that life originated in
the oceans. . . . Whether life might have gen-
erated on the land we do not know; on earth
it certainly did not.” The truth is that the
geologic record proves nothing whatever about
the origin or even the infancy of life. It
may be fairly doubted whether it takes us
back even to the middle age of the animal
kingdom. Such a dogmatic assertion is,
therefore, wholly unjustified. In this con-
nection it is hard to resist pointing out that
among the oldest known fossils are certain
Eurypterids (Walcott's Beltina danai) which
are generally interpreted as fresh-water
rather than marine forms.
Earther on we read, of the plants which
formed the Carboniferous coal beds, “Only a
warm, humid foothold and lambent air could
have given them such luxuriance and im-
pressed them with such speed.” Neither Mr.
Lowell nor any one else knows whether the
vegetation in the Carboniferous swamps grew
slowly or rapidly. We know only that they
produced a certain body of coal. That may
have taken a short time at a rapid rate, or a
long time at the slow rate; the results would
be the same. As to the warmth, it may be
remarked that coal seams are now in process
of growth in Alaska and Labrador and that
many of the Carboniferous plants show by
2 SCIENCE
their structures an adaptation to severe rather
than genial climatic conditions. Only a
little later than the Carboniferous period most
of the lands adjacent to the Indian Ocean ex-
perienced a glacial period, comparable to that
of recent times in Canada; and in Australia
the coal seams are interbedded with layers of
glacial drift. Does this bespeak a torrid
climate in middle latitudes at that time?
Even the moist conditions seem to have been,
as now, of local prevalence only, for aridity is
indicated by the Carboniferous red beds and
gypsum of Colorado and some other regions.
One of the terrestrial conditions which Mr.
Lowell finds it necessary to postulate in order
to bolster up his theory of Martian evolution
is a perpetual cloud envelope around the earth
down to about Mesozoic times—“ a shady
half-light” which he says is attested “by the
habit of the ferns of to-day.” That tree-
ferns now stand out isolated on the brushy
hills of equatorial Africa under the blazing
tropical sun is evidently unknown to the au-
thor. Under the circumstances he would
have found the services of a botanist advan-
tageous.
With the hypothesis of a perpetually damp
cloudy atmosphere we can hardly reconcile
the existence of deserts in India in the Cam-
brian, in New York in the Silurian, in Michi-
gan and New Brunswick in the Carboniferous,
and in Germany in the Permian period. Yet
the testimony of the rocks is emphatic that
they did exist in those times and places. -
Another of the author's preconceived opin-
ions of Mars, which the history of our own
planet has been twisted and Squeezed to fit, is
the shrinkage of the oceans and the eventual
disappearance of water in any form. Ac-
cording to Mr. Lowell, Mars had oceans but
lost them, and the earth is merely in an
earlier stage of the same process. As to the
earth, he says, “observation proves this to be
a fact,” and goes on to cite Professor Dana,
who many years ago propounded the opinion
that the lands had grown steadily larger from
small beginnings. If Dana were alive to-day
he would doubtless repudiate the idea, for it
is wholly contrary to the mass of facts more
recently made known. If Lowell were right,
land on the continent of North America would
have been smallest in the Archean and be
greatest now. The truth is that there have
been fluctuations of land and sea throughout
recorded geologic history, and these changes
show no general tendency. Just before the
Cambrian period the continent was nearly all
oute of water; at the close of that period it
was at least half submerged. At the close of
the Permian it emerged more extensively than
ever and yet in the Cretaceous it was again
deeply inundated. Examples of the same
thing could be largely multiplied, but are too
well known to make that necessary.
In the face of all these facts Mr. Lowell
coolly states that “wherever geologists have
studied them, the strata tell the same tale,”
viz., the land has spread, the ocean shrunk. . . .
No competent geologist would admit a word
of this. Yet on this comfortable basis of
fallacy Mr. Lowell then proceeds “Now, a
general universal gain of the sort can mean
only . . .” One is tempted to direct the au-
thor’s attention to his own preface wherein he
seriously admonishes that “the cogency of the
conclusion hangs upon the validity of each
step in the argument.” The reader can
judge for himself of the cogency of this par-
ticular conclusion.
Having assured his readers that the earth
is drying up and that it will sooner or later
“roll a parched orb through space,” he cites
as proof the alleged fact that deserts are in-
creasing in size. This is the beginning of
the dreadful end which “is as fatalistically
Sure as that to-morrow’s sun will rise, unless
Some other catastrophe anticipate the end.”
Here again the proverb applies, “a little
knowledge is a dangerous thing.” Mr. Lowell
has seen the petrified stumps and trunks of
trees in the Arizona desert and jumps to the
conclusion that deserts in general have been
steadily invading once forested regions, from
remote ages onward. Had he inquired into
the recorded facts of geologic history he
would have learned that deserts have existed
in many parts of the world ever since the
earliest periods, wherever topographic and
atmospheric conditions were favorable. It is
not probable that our present deserts are more
SCIENCE 3
extensive than those of the Permian period,
during which the saltest of salt lakes partially
covered the site of Germany.
I think enough has been said to show what
kind of pseudo-science is here being foisted
upon a trusting public. “Mars as the Abode
of Life" is avowedly a popular exposition of
a science, not a fantasy. Its author is a
highly educated man of distinguished connec-
tions and some personal fame. He writes in
a vivid, convincing style, with the air of au-
thority in the premises. The average reader
naturally believes him, since he can not,
without special knowledge of geology and
kindred sciences, discern the fallacies. He
has a right to think that things asserted as
established facts are true, and that things
other than facts will be stated with appropri-
ate reservation. This is precisely the same as
his right to believe that the maple syrup he
buys under that label is not glucose, but is
genuine. The misbranding of intellectual
products is just as immoral as the misbrand-
ing of the products of manufacture. Mr.
Lowell can not be censured for advancing
avowed theories, however fanciful they are,
for it is the privilege of the scientist; nor for
making unintentional mistakes in fact, for
that is eminently human. But I feel sure
that the majority of scientific men will feel
just indignation toward one who stamps his
theories as facts; says they are proven, when
they have almost no supporting data; and
declares that certain things are well known,
which are not even admitted to consideration
by those best qualified to judge. Censure can
hardly be too severe upon a man who so un-
scrupulously deceives the educated public,
merely in order to gain a certain notoriety
and a brief, but undeserved credence for his
pet theories.
ELIOT BLACKWELDER
UNIVERSITY OF WISCONSIN,
March 26, 1909
FAIR PIAY AND TOLERATION IN SCIENCE
To THE EDITOR OF SCIENCE: I have read with
surprise, if not indignation, Professor Black-
welder’s discussion of Lowell’s “Mars as the
Abode of Life " in your issue of April 23,
1909; and feel that it is only just to enter a
protest, in the interest of fair play and that
degree of toleration which has always been
characteristic of the better men of science.
Professor Blackwelder speaks as if some great
injury had been done to the public by the
appearance of a popular book, written in a
narrative style adapted to the lay demand.
Of course this is wholly untrue, and mere idle
vaporing. Lowell's popular works are all bet-
ter than Proctor’s and Flammarion’s, and both
of these latter writers have done valuable
service in diffusing the results of scientific
research among the multitude. It may sound
very plausible to the scientific recluse to say
that nothing but mathematical formulae and
tables are of value, but every well-informed
man knows better. It is by the popularization
of science that new interest is awakened in the
public mind and increased opportunities pro-
vided for the extension of scientific research.
To take a specific example, it was the read-
ing of a popular work by Huyghens, entitled
“Comotheoros,” which led Dr. Plume to es-
tablish the Plumian professorship of astron-
omy at Cambridge, which has been held by
Such distinguished mathematicians as Sir
George Darwin, who has greatly extended our
knowledge of mathematical astronomy, yet is
not so narrow as to deny the value of popular
Science, but on the contrary has contributed
to it by popular articles in magazines and a
standard work on the tides.
If we compare the present state of astron-
omy in the United States with that in other
countries, we shall be compelled to admit that
American preeminence is due very largely to
popular interest, and a general appreciation of
results. Without popular diffusion of the
results of scientific research, who among our
business men and captains of industry could
possibly have any interest in Scientific work?
4 SCIENCE
In this day of specialization even scientific
workers find it difficult to understand the
labors of others, and the public is at vastly
greater disadvantage. I make great use of
logarithms, trigonometry and calculus, but I
have yet to see the laymen who enthuse over
columns of figures or complicated mathemat-
ical analysis.
When Proctor was living he was assailed by
the self-appointed critics in much the same
was as Lowell is now; but they always forget
that there are others to be considered besides
the mere priesthood of science. It sometimes
seems to me that some of the latter are almost
as intolerant as those divinely inspired per-
sons who took it upon themselves to conduct
the inquisition during the middle ages. For
one, I am not at all prepared to admit the
justice of contemporary criticism, though in
the long run a moderate and just opinion will
prevail. This has been true in all ages and
professions, and therefore is not confined to
our own time or to any particular science.
Now as to some of the points cited by Pro-
fessor Blackwelder as objectionable:
1. He finds fault with Lowell for adhering
to Laplace's cosmogony; but let me point out
that this same cosmogony very slightly modi-
fied, to take account of tidal friction, has been
held by the most eminent mathematicians
abroad.” If such views have been held by
those who have spent many years on the sub-
ject, at such mathematical centers as Cam-
bridge, England, Surely Lowell may be excused
for not accepting the inconsistent and purely
destructive criticisms recently put forth at
Chicago by Chamberlin and Moulton. It is
only fair to say that no constructive results of
consistent character had been reached on this
subject till my own investigation was com-
pleted last year, of which an account is given
in Astronomische Nachrichten, No. 4308
(February, 1909), but which appeared too late
to be used in Lowell’s book. As I have worked
on this subject uninterruptedly for twenty-five
years, I am prepared to speak with some de-
gree of authority. If Professor Blackwelder
* Cf. paper by Mr. F. J. M. Stratton, on
“Planetary Inversion,” in the Monthly Notices
of the Royal Astronomical Society, April, 1906.
will study my last paper carefully, and the
work now in press, when it appears, he will
find that most of the recent speculations on
cosmogony are not worth the paper they are
written on; and yet some of them have been
published by the Astrophysical Journal and
the Carnegie Institution, just as other erro-
neous and misleading papers have often been
published by the Royal Society, the Paris
Academy of Sciences and other learned socie-
ties of standing. Every experienced investi-
gator recognizes the great amount of error
that creeps into scientific literature even of
the best type. How much more latitude, there-
fore, is to be expected in popular literature,
which in the nature of the case must be enter-
taining rather than strictly exact and ultra-
conservative
2. Great fault is found with Lowell’s claim
that in general the terrestrial continents have
been formed from the interior outwards,
though he justly cites Dana, one of the great-
est geologists of any age, in support of this
view. Now I venture to say that Professor
Blackwelder has not read carefully the four
memoirs recently published in the Proceedings
of the American Philosophical Society at
Philadelphia, in which I have examined this
question and the related topics with great
care; otherwise he would see that, however
deficient our knowledge may be as to details,
in general his contentions are absolutely with-
out foundation. In the opinion of many emi-
nent men of science, including some of the
foremost geologists and physicists, who have
done me the honor to read these papers, I have
proved that mountains are formed by the sea,
and not at all by the shrinkage of the globe;
and as the younger mountains are generally
mearest the oceans it follows that the oceans
are gradually drying up and the land increas-
ing, as Lowell maintains. Therefore Lowell is
right, and Blackwelder wrong; and that too in
a subject which he represents as his own.
Dana and Le Conte clearly understood that the
mountains are related to and have in some
way risen from the sea, but on the old con-
traction theory, now happily abandoned, they
could form no correct conception of the cause
of mountain formation. If Professor Black-
SCIENCE 5
welder is prepared to contest my results, let
him answer my argument on mountain forma-
tion in the case of the Aleutian Islands, where
I have proved that they are a submarine
mountain range now being pushed up by mat-
ter expelled from beneath the trench dug out
in the sea bottom to the south of these islands;
and that the whole movement is due to the
secular leakage of the ocean and the resulting
expulsion of lava beneath the crust, and noth-
ing else. On this point other geologists have
discreetly kept silent, but perhaps Professor
Plackwelder “will rush in where angels fear
to tread.”
3. Now in regard to life on Mars, it is
sufficient to say that Professor Newcomb has
justly remarked that the physical conditions
on that planet are very similar to those pre-
vailing in the Himalayas of Central Asia.
But even the tableland of Tibet is inhab-
ited, and maintains a respectable civilization.
As Lowell has proved that there are water
and clouds on Mars, and the polar snows
melt and disappear with the advance of the
Summer seasons on that planet, why may
there not be life there as well as here? Of
course there is life on Mars; there is no doubt
about it. But I am not prepared to say how
far advanced the creatures on Mars may be;
neither am I narrow enough to deny the
possibility of their high development.
Perhaps it will interest Professor Black-
welder and others to know that I have just
sent to the Astronomische Nachrichten and to
the American Philosophical Society extracts
from a letter of Euler, written in 1749, and
published in the Philosophical Transactions
of the Royal Society, before the cosmogonic
theories of Kant (1755) and Laplace (1796)
were put forward, in which the great Swiss
mathematician, then residing at Berlin, even
went so far as to say that the planets had
gradually neared the Sun from a great dis-
tance—thus implying that the earliest life
originated on these bodies in the depths of
space, before they came anything like so near
the sun as they now are. Arrhenius holds
a similar view to-day, and even thinks that
life is carried by germs from one world to
another.” In the work now in press, it is
shown, on new grounds, that all the fixed
stars are attended by systems of planets. Is
Professor Blackwelder prepared to claim that
all these billions of worlds are uninhabited?
If not, why is he so unreasonable about the
habitability of Mars? Lowell's view that there
is life in the other worlds is sure to triumph,
and we had as well come to it one time as
another.
4. Professor Blackwelder is sure that Lowell
is working for “a certain notoriety and a
brief but undeserved credence for his pet
theories.” Let us, in common fairness, have
no assignment of motives. These are seldom
known in any man, either by himself or by
others. If Professor Blackwelder is as candid
as he wishes others to be, he will now come
forward and say that there is much yet to be
learned in every branch of Science, including
geology, and about contemporary scientific in-
vestigators as well, and that according to the
best ethics, every tree must be judged by its
fruit.
Lowell has maintained for fifteen years a
magnificent observatory, which has carried
on valuable work on Mars, and the other plan-
ets and satellites; on double stars, both visual
and spectroscopic; on the spectra of the outer
planets; on comets and meteoric phenomena;
on meteorology as related to the best sites for
observatories; and on many other topics. He
has given many young astronomers a chance
to do good independent work, and the results
obtained are highly valued throughout the
world. What has Professor Blackwelder done
in comparison? And is he the one to say that
censure can not be too severe upon one who
has deserved so well of American men of sci-
ence as Professor Lowell has done? Let the
still voice of conscience answer | Emerson
says that alone all men are conscientious. If
so, we shall have a little more toleration, and
fair dealing, and less of this clique and faction
business, by which a man who is not in the ring
never can get justice or fair consideration.
Of all the evils which afflict American science
to-day the wide-spread tendency to partizan-
ship and factionism and the resulting total
* Cf. “Worlds in the Making,” Harper's, 1908.
6 * SCIENCE
disregard of the ultimate interests of truth, is
undeniably the worst. As the truth is difficult
to discover, and in the end will be found only
among the errors of the wise, it is clear that
every cause must be heard, and we must pre-
serve a tolerant and open-minded attitude
towards all contemporary work. Recent revo-
lutions in all branches of science have been so
great that no man knows, and no honest man
will attempt to predict, what a day may bring
forth. T. J. J. SEE
U. S. NAVAL OBSERVATORY,
MARE ISLAND, CALIFORNIA,
April 30, 1909
FAIR PLAY AND TOLERATION IN CRITICISM
To that large number who accept the jus-
tice, the value and the need of the recent
criticism by Blackwelder of the geological
fallacies dressed out as facts in Lowell’s book
on Mars as the abode of life, some reply will
seem called for to offset before the general
scientific public the personal, befogging and
dogmatic rejoinder which it evoked in a recent
issue of SCIENCE from one not a geologist.”
In this connection some preliminary statement
may well be made as to the kind of articles
which in the mind of the writer seem to call
for certain kinds of criticism. This appears
the more necessary since to some all criticism
seems out of place and to indicate a carping
disposition, while others would hold that spe-
cialists are too lax in permitting to pass un-
challenged many works which are highly erro-
neous but whose character is evident to the
specialist only.
Destructive criticism is to all constructive
workers in science a disagreeable task, yet one
which should often be regarded as a duty,
especially to university teachers, since such
are deeply interested in the general diffusion
of knowledge and should be equally concerned
in the prevention of that diffusion of error
which, unless vigorously combated, takes the
place of truth.
All research work, even by properly quali-
fied men, must necessarily contain some per-
centage of error which is eliminated by fur-
ther advances in knowledge, but which fre-
quently serves a most valuable purpose in
stimulating to further and more exact ob-
servation and analysis. Such work, addressed
* “Fair Play and Toleration in Science,” by T.
J. J. See, professor of mathematics, U. S. Navy,
SCIENCE, Vol. XXIX., pp. 858–60, May 28, 1909.
to specialists, is always worthy of more praise
than criticism, and a proper review will always
seek out the parts of value and give them more
prominence than those features which in the
mind of the reviewer may seem open to ques-
tion or even to miss the truth. It is not such
research work which is here under discussion.
Advancement of knowledge, however, im-
plies not only abstruse technical researches,
but popular expositions of the same which
shall carry a vivid conception of the principles
and results to the intelligent but unprofes-
sional public, consisting of laymen as well as
workers in other branches of knowledge. Such
work when well done is regarded by scientists
in general as of the very highest educational
value, and many eminent men have contrib-
uted a part of their time to the development
of popular Science. In fact, no small part of
the eminence of some of the best known and
highly regarded men of science is due to their
work in what may be called the popular field,
since it reaches those whose professional in-
terests are in other branches. It is obvious
that it is not against work of such character
that Blackwelder’s review is directed.
Again, there is a large class of fugitive
popular scientific literature written by men of
no personal reputation, bearing within it the
marks of its unauthoritative nature, some of
it good, some bad. Such articles hardly call
for serious comment from specialists.
But there are popular works ably written
and put forth in a garb of authority which,
however, confuse facts, theories and hypoth-
eses, and contain views regarded by the great
body of those qualified by special knowledge
to hold an opinion as outworn, or wholly erro-
neous and misleading. It is against such
SCIENCE • 7
false science, not popular science, that public
and severe censure becomes a duty. As Black-
welder admirably puts it, unless such criticism
is directed against such a book and its author
“the average reader naturally believes him,
since he can not without special knowledge
discern the fallacies. He has a right to think
that things asserted as established facts are
true, and that things other than facts will be
stated with appropriate reservation. This is
precisely the same as his right to believe that
the maple syrup he buys under that label is
not glucose, but is genuine. The misbranding
of intellectual products is just as immoral as
the misbranding of the products of manu-
facture.”
This code of morality makes it the duty of
the teacher and scientist to expose in print
such scientific shams, a duty, however, which
is always disagreeable and which the majority
of men leave to their fellows to do. He whose
time is fully occupied with teaching and re-
search, but who turns aside to do the task
which others have left undone, is therefore
deserving of honor and not of abuse.
It is noteworthy that Lowell’s book on
“Mars as the Abode of Life,” in spite of its
mass of fundamental errors whenever geolog-
ical matters are touched upon, errors palpable
to every working geologist, has been before the
public for more than a year without any criti-
cism of these features appearing in SCIENCE,
the official organ of the American Association
for the Advancement of Science, an associa-
tion which since the development of special
societies has become devoted to the general
broadening of scientific knowledge. Such a
criticism seems especially called for, since the
book has been given the very widest publicity,
it deals with a subject of great popular in-
terest, and its author has been grandiloquently
advertised by his publishers as the “founder
of the new science of planetology.” As an
illustration of the result it may be noted that
in the scientific columns of a carefully edited
popular weekly its author has been hailed as
one who would henceforth relieve America
from the European taunt that it has as yet
produced no really great and creative man of
science.
As an offset, however, to the necessarily
severe criticism of “Mars as the Abode of
Life,” cordial recognition may well be given
at the same time to that great enthusiasm
manifest in all of Lowell’s work, which has
led to the founding of a magnificent observa-
tory and has contributed to astronomy much
of real value. A coming generation of scien-
tists will find much to regard highly in Lowell
and will see in his work a stimulus to further
knowledge, but will hold it as unfortunate that
the same temperament which led to these re-
sults should have given rise to writings which
called forth such severe criticisms as have
appeared from his contemporaries in order to
separate errors of premise and conclusion from
that which is of real value.
Having made these preliminary statements,
the true character of See's arraignment of
Blackwelder may be shown by calling atten-
tion to the several topics which are discussed.
Blackwelder’s review is aimed at false sci-
ence, not against popular science, regarding
which he says not a word; yet See uses a
column and a half to flay him on that score,
and because Blackwelder criticizes Lowell, as-
sumes that the criticism is aimed also against
the popular work of such men as George Dar-
win and Proctor.
Blackwelder specifically avoids discussing
any astronomic phase of the book, and does
not mention the subject of life on Mars. Yet
See takes up a column in arguing this matter,
and states: “Of course there is life on Mars;
there is no doubt about it.”
Lowell has been fortunate in being able to
personally build and maintain an observatory,
which has been the means of advancing the
science of astronomy in a number of lines.
See asks what Blackwelder has done in com-
parison. This question implies that only those
whose personal fortunes have enabled them to
do what Lowell has done should criticize his
work, since those famaliar with the scientific
results of both will hardly see cause on such
lines for invidious comparison.
Blackwelder casually mentions, to the ex-
tent of one sentence, “Lowell’s implicit belief
in the Laplacian hypothesis which now, to say
the least, is on the defensive,” a remark which
8 SCIENCE
calls forth a column from See embracing such
statements as “If Professor Blackwelder will
study my own (See's) paper carefully, and the
work now in press (by See) when it appears,
he will find that most of the recent specula-
tions on cosmogony are not worth the paper
they are written on.”
See further states that he has proved in four
memoirs “that the oceans are gradually dry-
ing up and the land increasing, as Lowell
maintains. Therefore Lowell is right and
Blackwelder wrong; and that too in a subject
which he represents as his own.” This state-
ment is highly amusing, to say the least, to
those cognizant of recent work on paleogeog-
raphy, especially if they have also read See's
voluminous publications on mountain build-
ing and related subjects, and noted that they
center about the old hypothesis of a free down-
ward permeation of ocean water. A hypoth-
esis which is not open to direct proof, and
though still advocated by certain physicists
and geologists is distinctly relegated to a sub-
ordinate rôle by many economic geologists and
such leaders in the more philosophic side of
the earth-science as Suess, Chamberlin and
Van Hise; partly because of the theoretical
difficulties attending an effective downward
diffusion of ocean water through the zone of
rock flowage, but much more because of the
failure of the hypothesis to account for many
of the facts now known to geologists. These
point rather to a directly opposite view, which
is well expressed by the words of Suess, “wol-
canoes are not fed by infiltration from the sea,
but the waters of the sea are increased by
every eruption.”
The voluminous nature of See's writings on
the subject is due to a dressing out of this old
and, to say the least, doubtful hypothesis with
many speculative additions, with much repeti-
tion of well-known facts and theories, and
with specific applications in such frequent
obvious discord with modern teaching of the
principles of physiography and known details
of geologic structure and history, that no geol-
ogist has felt called upon to comment. In the
words of See, “geologists have discreetly kept
silent.” -
On every topic See cites his own work as
the authoritative utterances on the subject,
and in the last paragraph denounces, as the
worst evil of American science, “this clique
and faction business, by which a man who is
not in the ring never can get justice or fair
consideration.” Since no group of geologists
or, so far as the writer is aware, no single
geologist of recognized standing has followed
and promulgated the special views in the
teachings of See and Lowell, this clique and
faction evidently includes the several hundred
working geologists of America. To those who
are familiar with the situation, this gives the
key to the whole of See's article on “Fair
Play and Toleration in Science.” It is a
vicarious castigation in which Blackwelder
stands to receive the blows for a host of un-
named men of science, because they have not
accepted See's memoirs at the valuation which
he places upon them. Is vicarious atonement
“fair play and toleration in science ’’’
Joseph BARRELL
NEW HAVEN, CoNN.,
June 15, 1909
REMAIRES ON RECENT CONTRIBUTIONS TO COSMOGONY
To THE EDITOR OF SCIENCE: In your issue of
May 28 is a letter by T. J. J. See, ostensibly
demanding “fair play and toleration ” in the
consideration of current contributions to sci-
ence, but clearly written for the purpose of
exploiting some of his own recent writings.
In this letter, notwithstanding the implica-
tions of its caption, he takes occasion to char-
acterize the work of Professor Chamberlin and
myself as “inconsistent and purely destruc-
tive,” and says:
If Professor Blackwelder will study my last
paper carefully, and the work now in press, when
it appears, he will find that most of the recent
speculations on cosmogony are not worth the
paper they are written on; and yet some of them
have been published by the Astrophysical Journal
and the Carnegie Institution.
SCIENCE - 9
He also modestly states:
It is only fair to say that no constructive re-
sults of consistent character had been reached on
this subject till my own investigation was com-
pleted last year. . . . As I have worked on this
subject uninterruptedly for twenty-five years, I
am prepared to speak with some degree of au-
thority.
Because of these extravagant pretensions
and the fact that a majority of the readers of
ScIENCE, being unfamiliar with the details of
recent developments in this subject, will not
credit any one with having the monumental
nerve to put forward such claims without
there being some basis for them, I beg the
privilege of taking enough space to state
briefly the facts relating to this matter.
The well-known nebular hypothesis was put
forward briefly by Laplace, in 1796, at the end
of a work on popular astronomy. Its sim-
plicity and attractiveness, as well as the great
name of its author, soon gained for it wide
acceptance among scientific men. It satisfied
those racial instincts for an explanation of the
origin of things which gave rise to the cos-
mogonies of the ancients; and in stirring the
emotions, the majestic sweep of events which
it described took the place of the heroic deeds
celebrated in their epics. But its greatest
value was in making, in the first half of the
nineteenth century, a foundation for the de-
velopment of geological theories respecting
the age and evolution of the earth, and these
theories, in turn, were important factors in
Darwin’s elaboration of his “Origin of
Species.”
The next important step in cosmogony was
Helmholtz's contraction theory of the heat of
the sun, published in 1854, which not only was
not contradictory to the Laplacian theory, but
was generally supposed to be a proof of its
Correctness. -
In the latter half of the nineteenth cen-
tury the Laplacian theory was supplemented
by the consideration of some factors originally
omitted, chiefly by Roche and Sir George Dar-
win, and some objections were urged against
it, chiefly by Babinet and Faye. But the
writings of practically all astronomers show
that it was generally accepted without funda-
mental modifications. For example, Sir
George Darwin in his classical researches on
tidal evolution frankly stated that he ac-
cepted it in its main outlines; and in 1886 C.
Wolf, of the Paris Observatory, reprinted in
book form a series of articles appearing earlier
in Bulletin Astronomique, Wols. I. and II.,
which clearly supported this theory. In the
preface to this volume we read:
Mon principal but, en écrivant ces articles, était
de montrer que la théorie de Laplace répond
encore aujourd’hui le mieux possible aux condi-
tions que l’on est en droit d'exiger d’une hy-
pothèse cosmogonique.
In the late nineties Professor Chamberlin
in studying the earth's atmosphere, and par-
ticularly its origin and history, became skep-
tical of the soundness of the Laplacian theory;
and simultaneously some of its weaknesses
were forced on me while considering it in my
classes in descriptive astronomy. Toward
the end of 1899 we had several conferences
on the question of its correctness, and as a
result of these discussions we decided to test
it, first as to its agreement with the facts es-
tablished by observations, and secondly as to
its self-consistency. The results of these in-
quiries are contained in a paper published by
Professor Chamberlin in the Journal of
Geology, February–March, 1900, and in one
by myself in the Astrophysical Journal,
March, 1900. It is well known that the con-
clusions reached in these papers seemed to us
so adverse to the theory as to compel us to re-
ject it as being no longer a satisfactory hypoth-
esis; and since that time many astronomers
have placed themselves on record as being in
agreement with us. -
Immediately after the publication of these
papers constructive work was begun, chiefly
by Professor Chamberlin. The first account
of the new hypothesis which was developed
was published by Professor Chamberlin in
Year Book No. 3 of the Carnegie Institution,
pp. 208–253 (1904), and another was pub-
lished by myself in the Astrophysical Jour-
mal, Vol. 22, pp. 165–181 (1905). In Cham-
berlin and Salisbury’s “Geology,” Vol. 2, pp.
38–81 (1906), under the title of The Planet-
esimal Hypothesis, Professor Chamberlin
10 SCIENCE
gives an extensive account of the proposed
theory. Some of the subheadings are: Sub-
varieties of the Hypothesis, The Hypothetical
Origin of the Solar Nebula, The Contingencies
of Stellar Collision, The Contingencies of
Close Approach, The Special Consequences of
Close Approach, The Acquisition of Rotatory
Motion, The Result a Spiral Nebula, The
Assigned Nebular Origin not Vital, The Evo-
lution of the Nebula into Planets, The Part
Played by Ellipticity of Orbit, The Evolution
of Circularity, The Time Involved, The Bear-
ing of the Mode of Accretion on the Direction
of Planetary Rotation, The Spacing-out of
the Planets, . . . He closes the chapter with
the following summary:
The planetesimal hypothesis thus assumes that
the solar system was derived from a nebula of
the most common type, the spiral, and that the
matter of this parent nebula was in a finely
divided solid or liquid state before aggregation,
in harmony with the continuous spectra of spiral
nebulae. It regards the knots of the nebula as the
nuclei of the future planets, and the nebulous
haze as matter to be added to the nuclei to form
the planets. It assumes that both the knots and
particles of the nebulous haze moved about the
central mass in elliptical orbits of considerable,
but not excessive, eccentricity. It postulates a
simple mode of origin of the nebula connected
with the not improbable event of a close approach
of the ancestral sun to another large body, but
the main hypothesis is not dependent on this
postulate.
It assigns the gathering-in of the planetesimals
to the crossing of the elliptical orbits in the
course of their inevitable shiftings. Out of this
process and its antecedents, it develops consistent
views of the requisite distribution of mass and
momentum, of the spacing out of the planets, of
their directions of rotation, of their variations
of mass, of their varying densities, and of other
peculiarities.
It deduces a relatively slow growth of the earth,
with a rising internal temperature developed in
the central parts and creeping outward. With
such a mode of growth, the stages of the earth’s
early history necessarily depart widely from those
postulated by the Laplacian and the meteoritic
hypotheses. These stages now claim our atten-
tion.
In , rny “Introduction to Astronomy,” pp.
463–487 (1906), I have discussed the same
theory under the title of The Spiral Nebula
Hypothesis. Some of the headings of the
articles in this section are: Hypotheses Re-
specting the Antecedents of our Present
System, A Possible Origin of Spiral Nebulas,
The Development of the Solar System from
a Spiral Nebula, The Origin of Planets, The
Origin of Satellites, The Planes of the
Planetary Orbits, Rotation and Equatorial
Acceleration of the Sun, The Small Eccen-
tricities of the Planetary Orbits, The Rota-
tions of the Planets, The Eccentricities of the
Satellite Orbits, The Moment of Momentum
of the System, The Evolution of the Planets,
The Age of the Solar System, The Future of
the System. . . . The chapter is closed with
the following summary
The first word should be one of warning that
the theory which has been sketched briefly should
not be accepted as final. There are many points
where quantitative results must be obtained and
compared with our actual system. There may be
many modifications of it possible and necessary.
For example, the genesis of spiral nebulas may be
different from that postulated above.
The hypothesis of an original spiral nebula is
suggested by recent photographs of nebulas as
well as by the system itself. The conditions which
are supposed to have given rise to the spiral
nebula seem most reasonable in view of the mo-
tions of the stars. The development of a spiral
nebula by the near approach of two suns seems
to be a necessary consequence, though this point
needs further elaboration. The development of
some such a system as ours from a small spiral
nebula of the type considered seems to be inevit-
able. So far as the details have been worked out
nothing directly contradictory to the theory, or
even seriously questioning it, has been found,
while it explains admirably all the main features
of the system. It can be safely said that, at
present, this hypothesis satisfies all the require-
ments of a successful theory much better than any
previous one.
Since the publication of these books the
work of elaborating and testing the theory has
been carried forward by both Professor
Chamberlin and myself, and a part of the re-
sults obtained have been published by the
Carnegie Institution.
The alleged twenty-five years of uninter-
rupted work upon the evolution of the solar
SCIENCE 11
system by See have resulted only in the fol-
lowing papers so far as I am aware: (1)
“Significance of the Spiral Nebula,” Popular
Astronomy, pp. 614–616 (December, 1906);
(2) “On the Cause of the Remarkable Cir-
cularity of the Orbits of the Planets and
Satellites and on the Origin of the Planetary
System,” Astronomische Nachrichten, No.
4308 (February 24, 1909), the same paper
printed in Popular Astronomy, May, 1909,
and at least the substance of the same paper
communicated by its author to the Chicago
Record-Herald early in 1909.
In the paper in Popular Astronomy, written
over the date October 23, 1906, See makes the
following statements:
For a number of years the writer has given
consideration to the probable nature of the spiral
nebulae, and their importance has been consider-
ably increased by photographs obtained by Roberts
and Keeler, and more recently at the Yerkes
Observatory. Certain speculations have been in-
dulged in which implied that the spiral nebulae
are true nebulae condensing into systems of stars.
Though this premature and unauthorized line of
thought has been extensively exploited, and even
given place in one treatise on geology, it has
always seemed to the writer quite unsound. I
have consistently held that so far we do not know
the true character of the spiral nebulae, and this
position is amply justified by the penetrating
remarks of M. Poincaré. Whether the spiral neb-
ulae are other Milky Ways, as suggested by the
illustrious French geometer, time alone can tell;
and it may be several centuries before this ques-
tion can be satisfactorily settled. Meanwhile the
exploitation of the spiral form as typical of neb-
ular development is certainly misleading, for, as
Poincaré points out, there is no proof that these
spirals are true gaseous nebulae.
The speculations on spiral nebulae have been
decidedly overdone, and it is time to call a halt.
There is not the slightest probability that our
solar system was ever a part of a spiral nebula,
and such a suggestion is simply misleading and
mischievous. The great circularity of the planet-
ary orbits shows the absurdity of such an hy-
pothesis. . . . Least of all can we expect any light
from the much exploited spiral nebulae, which as
M. Poincaré justly remarks, may be other galaxies.
It is time, therefore, to drop such spirals from
our text-books, or to candidly admit that we are
quite in the dark as to their true significance.
In the last paper of See recently published
in the Astronomische Nachrichten and several
other places we read:
The solar system was formed from a spiral
nebula, revolving and slowly coiling up under
mechanical conditions which were essentially free
from hydrostatic pressure. And spiral nebulae
themselves arise from the meeting of two or more
streams of cosmical dust. The whole system of
particles has a sensible moment of momentum
about some axis, and thus it begins to whirl about
a central point, and gives rise to a vortex. In the
actual universe the spiral nebulae are to be counted
by the million, and it is evident that they all
arise from the automatic winding up of streams
of cosmical dust, under the attraction of their
mutual gravitation. . . . When the nebula rotates
and the coils wind up in such a way as to leave
open spaces between the coils, or at least freedom
from sensible hydrostatic pressure, the usual re-
sult is the development of a system made up of
small bodies, such as the planets compared to the
greatly preponderant sun, or the satellites com-
pared to the much greater planetary masses which
control their motions. In the solar system where
the conditions are accurately known this is proved
to have occurred; and it was repeated so many
times always with uniform results giving a large
central mass and small attendant bodies that the
general law for this condition is clearly es-
tablished.
Thus we see the variety of “ consistent ’’
conclusions recently reached by the twenty-
five years of uninterrupted work on this
subject.
At the end of this paper See admits its
value in the following modest terms:
It has seemed advisable to call attention to the
cause of the roundness of the orbits of the
planets and satellites, because it appears likely
that the criteria, now introduced may go far to-
wards clearing up the mystery which has always
surrounded the origin of our solar system.
In See's paper there are only two points of
divergence from the ideas fully developed by
Professor Chamberlin and myself. The first
is that spiral nebulas have their origin in
“ the meeting of two or more streams of
cosmical dust.” The second is that satel-
lites are captured bodies. This latter view has
been advanced by many amateurs and a
few astronomers. It was considered in my
12 SCIENCE
writings quoted above, and rejected for what
seemed to me to be good reasons. The resist-
ing medium on which so much stress is laid is
simply a special case of the collisions of any
character considered by Professor Chamberlin
and myself.
The quotations above are sufficient to re-
move the clouds which See's pretensions of long
study of, and valuable contributions to, this
subject might raise in the minds of those not
particularly familiar with the history of
recent developments in cosmogony. I wish
to point out that notwithstanding the evi-
dence furnished by his 1906 paper of his
MARS AS THE
THE recent letters in SCIENCE on the geo-
logic facts in “Mars as the Abode of Life"
have an origin which readers of SCIENCE
should have the opportunity to know. The
geologic facts in “Mars as the Abode of Life"
are taken from recognized sources, chiefly
Dana, Geikie, Dr. Lapparent and recent re-
search; only the weaving together is new.
They are not res gratae to certain geologists
because they clash with a new cosmogeny de-
vised by the Chicago geologist, Professor
Chamberlin, who associated with himself for
the mechanical and mathematical proof of it,
on which all such hypotheses must rest, the
assistant professor of astronomy of his uni-
versity, Professor Moulton.
tinent, therefore, to consider the basis of their
belief which is necessarily astronomic. From
the latter writer’s exposition of the hypoth-
esis given in most detail in his “Introduction
to Astronomy,” we shall now quote.
We shall begin with a statement on page
380, which in itself is sufficient to render the
reader cautious when he finds himself adven-
tured later upon the exposition. It is with re-
gard to the speed of meteors when they strike
the earth. It runs as follows:
Let us assume provisionally that the meteors
are moving around the sun in sensibly parabolic
orbits, like the orbits of the comets, and let us
find the greatest and least velocities with which
they can encounter the earth's atmosphere. If it
were not for the earth’s attraction they would
It becomes per-
familiarity with our work, and in spite of the
fact that at his request I furnished him re-
prints of my papers several months in ad-
vance of his recent publication, there is in it
no direct or indirect reference to Professor
Chamberlin or myself. Ordinarily such
conduct justifies the use of strong terms in
characterizing it, but in the present case I
believe astronomers and others who are famil-
iar with the situation will fully agree with
me that these aberrations are more deserving
of pity than of censure.
F. R. MOULTON
June 10, 1909
ABODE OF LIFE
pass the earth’s orbit at the rate of twenty-five
miles per second, the velocity being independent
of the angle at which they crossed. The earth’s
attraction would generate a velocity of nearly
Seven miles per second in a body falling from an
infinite distance into its atmosphere, whether the
sun were attracting it or not. The greatest rela-
tive velocity will be when the earth and meteor
meet, which is 25 + 7 - 18 = 50 miles per second.
The least will be when the meteor overtakes the
earth, which is 25 + 7 — 18 = 14 miles per second.
Now the velocities due to the sun's attrac-
tion and to the earth's upon a particle falling
to the latter under the action of both can not
be added in this simple manner.
The geometric explanation why the veloc-
ities can not be directly added is that when
each body is supposed to act alone the times
involved in their actions are different, while
when they act together these are naturally the
same. In the latter case the velocity due the
sun hurries the particle through the space
faster than the earth's pull alone could and so
gives the earth less time to act.
For the analytical solution of the problem
the reader is referred to a paper in the Astro-
nomical Journal, No. 601, in which he will find
that the speed the earth can impart depends
on the mode of approach, that it can never ex-
ceed 2.66 miles per second and may fall as low
as 0.53 mile.
We shall now go on to what concerns the
hypothesis more directly. The first point we
SCIENCE 13
shall mention is found on page 460. In the
criticism of the suggestion that “when Saturn
extended out to the orbit of the ninth satel-
lite, it rotated in the retrograde direction with
the period of this body,” the book says:
When the rotation period of the nebulous mass
equaled that of its revolution, it filled some space
as that indicated by the dotted curve in Fig. 168.
Up to this time the tides generated by the sun had
increased its moment of momentum by changing
it from a negative quantity to a certain positive
quantity. After this time the tides generated by
the sun decreased its moment of momentum, for
they always retarded the rotation. Therefore, if
the theory is true, the greatest moment of mo-
mentum in the whole history of the Saturnian
system should be found when the day and year of
its nebula were equal.
The fallacies here are two: (1) It is sup-
posed that the sun-tides would act solely in the
Saturnian plane; whereas they would undoubt-
edly turn the system over in the act. (2) The
moment of momentum here considered is that
of the solar system; whereas in the generation
of satellites it is that of the Saturnian system
itself, a totally different matter; so that the
supposed destructive proof falls to the ground.
The next point is on page 480, where we are
told with regard to the acceleration of a satel-
lite nucleus by a particle m that
It is found by a mathematical discussion that
this always results if the eccentricity of the orbit
of m is greater than
r | ?,
#4. N*,
where R is the radius of the orbit of the planetary
nucleus around the sun, r the radius of the satel-
lite nucleus around M, and M the mass of the
planetary nucleus expressed in terms of the sun’s
mass. In the case of the earth and moon the
limit comes out 0.035, but in the case of the larger
planets and closer satellites it is very much larger.
Now the determining equation is
1 #–N 2 1.
R T Wºr Er – 2 T a
where
a(1 + e) = R — r
whence
MR r IM MR
e=2 N=–2M-5–F
7.
+M + .
or taking terms of the first order only
e== 2 MR_ *approx.
ºr r
Comparing this with the printed value we see
that a term of the first order has been omitted
and one of the second kept. The result is
that with Jupiter and his fourth satellite we
have
true value e = 0.86
planetesimal value e = 1.26
or actually a hyperbolic orbit.
The next point is from pages 478 to 481.
The book says, speaking of the effect of par-
ticles inside the planet's orbit:
The satellite nucleus is carried forward by the
motion of M, while it moves backward in its
revolution around M. The latter is a much slower
motion than the former. . . . It follows from the
direction of motion of the satellite nucleus that
in this case its motion around M will be acceler-
ated by its collision with m. . . . The effect of the
accelerations by the scattered material is to en-
large the orbit of the satellite nucleus, and to
prevent its being drawn down upon the growing
planetary nucleus.
Now the speeds of the larger planets and of
their satellites are as follows:
Speed in Miles per Second
Of Primary Of Satellite
in Orbit about Primary
Jupiter 8.1
Sat. 1 10.7
8.5
6.7
5.1
:
Saturn 6.0
Sat. 9.0
8.2
7.9
6.3
5.3
3.5
2.0
i
Uranus 4.2
Sat. 1 3.5
2 2.9
3 2.3
4 2.0
Neptune 3.4
Sat 1 2.7
On the very face of the table it will be seen
that six satellites contradict the book. When
14 - SCIENCE
we get into it deeper we find they all do. Thus
if we suppose the colliding particles to be
equally distributed in space we have for those
within the planet's orbit:
1 (2a – 1)}%a%da
J. Jada
for their mean velocity at the point of col-
lision; a being the semi-major axis of any par-
ticle.
This equals 0.79 of the planet's orbital speed.
A result substantially similar is got for any
other possible distribution.
From this it appears that all the large satel-
lites of all the large planets have spatial
speeds which would cause them to be retarded
by such impacts or exactly the opposite of
what the book states. So that the Supposed
proof by this of the planetesimal hypothesis
turns out to be a disproof of it. e
From what we have said it will be seen that
the hypothesis expounded will not work. -
PERCIVAL LOWELL
GEOLOGY AND COSMOGONY
To THE EDITOR OF SCIENCE: 1. In reply to
Professor Barrell’s communication in your
issue of July 2, 1909, it is sufficient to say
that he carefully passes over the legitimate
question under discussion, which is that the
mountains are formed by the sea, and not at
all by the shrinkage of the earth, as taught in
most of the books on geology. Since he has
thus evaded the issue, his long-drawn-out dis-
cussion requires no further notice.
2. In reply to Moulton’s statement in your
issue of July 23, let me say that my work on
the spiral nebulae and on the formation of the
solar system, under the secular action of a
resisting medium, was essentially completed
July 14, 1908, and my subsequent application
for copies of his papers (received here in
October, 1908) was simply to enable me to
make exact references in some of the argu-
ments refuting his theories. This is well
known here, for I was all the while in frequent
consultation with members of the astronomical
and mathematical faculty at Berkeley, and
they were fully informed of the results at
which I had arrived. My results were held
back for over six months (cf. A. N., 4308),
and so new did the conclusions appear to the
astronomers of the Pacific coast that when my
paper was given to the Astronomical Society
of the Pacific, January 30, 1909, several of
them stated in public interviews in the San
Francisco papers that they were exactly the
opposite of previous theories.
3. In the Astrophysical Journal for October,
1905, Moulton develops a theory that spiral
nebulae are formed by one star passing by
another, and causing spiral ejections of prom-
inences under tidal forces. This idea seems to
have originated with Chamberlin, as outlined
in his paper on the “Function of Disruptive
Approach, etc.” Here are some of the argu-
ments against these Chamberlin-Moulton the-
ories: If such tidal disruptions were in prog-
ress, spiral nebulae would be prevalent in the
Milky Way, and above all in globular clusters;
such is not the case. Perrine has recently
shown, in Lick Observatory Bulletin No. 155,
that the globular clusters are quite devoid of
nebulosity of any kind. Lastly, if spiral
nebulae are due to the disruption of one star
by another, then both stars would usually be
disrupted in passage, and spiral nebulae should
thus occur in pairs, which is not a fact. This
theory of spiral nebulae is therefore directly
contradicted by the most obvious phenomena
of the heavens.
4. In the same number of the Astrophysical
Journal it is announced that Saturn's ninth
satellite, Phoebe, can not now escape from the
control of the planet, so, “conversely, it has
never come under Saturn's control from a
remote distance.” Of course this interpreta-
tion of the use of Jacobi's integral is wholly
unjustifiable. Under the secular action of a
resisting medium such a capture is perfectly
possible, and it has actually taken place, not
* Astrophys. Jour., 14, 17–40, 1901.
SCIENCE 15
only for the retrograde satellites, but for all
of them.
5. The planets and satellites could have been
formed in but one or more of the three follow-
ing possible ways, and in no others whatsoever:
(a) Detached from their central masses by
acceleration of rotation, as imagined by La-
place. (b) Captured from the outer parts of
a nebula devoid of hydrostatic pressure and
thus added on from without, as announced by
the writer in A. N., 4308. (c) Formed right
where they now revolve by the agglomeration
of cosmical dust.
Now the possibility (a) is forever excluded
by what I have called Babinet’s criterion
(A. N., 4308); while (c) will not be seriously
considered by any one of ordinary understand-
ing. This leaves (b) as the only possible
mode of formation.
6. Not content, however, with proving by the
logical process of exclusion that the planets
and satellites were captured, I have since de-
veloped a rigorous proof, based on a correct
interpretation of Jacobi's integral under the
physical conditions existing in actual nature,
of just how the capture of satellites comes
A REPLY TO DR.
To THE EDITOR OF SCIENCE: In your issue of
September 10, Dr. Percival Lowell alleges that
I have made four mistakes in my “Introduc-
tion to Astronomy,” and from these alleged
mistakes as premises he draws the unique con-
clusion that the planetesimal hypothesis “will
not work.” Quite apart from the validity of
the allegations, it is, to me, a novel idea in
logic that errors made in trying to support a
proposition become thereby “disproof of it.”
One might infer by this sort of reasoning that
the errors of the class-room have long since
destroyed all the principles of mathematics.
The logic of the present case is all the more
remarkable in that two of the four alleged
mistakes do not occur in my discussion of the
planetesimal hypothesis at all, while the two
that do relate to it are really one, and it is not
shown that even this one has any critical re-
lations to the hypothesis.
about. A series of papers on this subject is
just now appearing in the Astronomische
Nachrichten, No. 4341–42, 4343, etc.
7. It is thus proved that the planets were
captured by the Sun and have gradually neared
that central mass under the secular action of
a resisting medium. This cause and no other
has given the orbits their round form. It is
proved also that the satellites likewise were
captured by their several planets. If Moulton
and Chamberlin have reached any but nega-
tive results, I have not yet seen them, and I
shall look forward with interest to their pub-
lication. Since naturally a thing has occurred
in but one way, it is evident that there are in
general an infinite number of ways in which
it did not occur. Such negative results may
be as numerous as the sands of the sea, or as
the points in space; but they will no more
nourish our minds than empty space will feed
our bodies. I submit that protest against
such vacant results is certainly justifiable.
T. J. J. SEE
|U. S. NAVAL OBSERVATORY,
MARE ISLAND, CALIFORNIA,
August 2, 1909
PERCIVAL LOWELL
The first point raised by Dr. Lowell is in
reference to the greatest and least velocities
which meteors moving in parabolic orbits can
have relatively to the earth, and in this dis-
cussion, which appears eighty-three pages be-
fore I have mentioned the planetesimal hy-
pothesis, I have made an error for which I
offer no excuse. In fact, it was quite inex-
cusable because I had fully treated, four years
earlier, in my “Celestial Mechanics’ (chapter
VII.), the question of the motion of an
infinitesimal body relatively to that of two
finite bodies describing circles, and the veloc-
ity of impact of meteors is only a special case
under it. If Dr. Lowell had been as generous
in citing this earlier and fuller treatment as
in quoting my brief remarks in the “Intro-
duction to Astronomy,” he could have omitted
a considerable part of his own paper in the
Astronomical Journal, whose method does not
16 SCIENCE
differ in any essential way from my exposition
of the question. In fact, it would have been
necessary only to have determined the con-
stant of integration of my equation (7), page
186. But I made a mistake, and this seems to
fix a new principle in logic with a quantitative
function: a mistake in expounding one propo-
sition, if made within 83 pages of the discus-
sion of another proposition, throws discredit
on the latter.
If it were not for the new logic, Dr. Lowell's
second indictment would have nothing to do
with the planetesimal hypothesis, for the al-
leged error occurs in a discussion of the
Laplacian theory in connection with the ninth
satellite of Saturn. In this, I have used only
the universally accepted principle of dynamics
that the moment of momentum of any mass
about an axis can be changed only by a
couple about the same axis. I can not accept
the interpretation Dr. Lowell puts on my
words, nor admit the correctness of his con-
tention.
The statements which contain the third
and fourth alleged errors do, indeed, appear
in my discussion of the planetesimal hypothe-
sis. They are quoted by Dr. Lowell, one as
being “on page 480,” and the other as being
“from pages 478 to 481.” They are, however,
not only a part of the same discussion, but are
in a single short paragraph on the same page
(480). The third alleged error is in a formula
occurring at the end of the fourth alleged
erroneous statement, and gives the precise
condition under which the conclusion reached
is true. I suppose it is a part of the new logic
to divide what is indivisible by the old logic,
to invert the order, to give reference to the
specific page of one, and to state simply that
the other lies between certain pages; or, the
last may be for rhetorical effect, as it avoids
the repetition of a page-number, which might
become monotonous if given more than once.
Not being as yet very familiar with the new
logic, I will, with Dr. Lowell’s permission,
treat the statements in the order in which they
occur in my book. The point in question is
the effect of the collision of meteoric masses
upon the dimensions of satellite orbits, par-
ticularly in the earlier stages of their develop-
ment. By carefully omitting, in his last quo-
tation, the sentences in which I have given the
conditions under which my conclusions are
true, he has made it appear that I have made
categorical statements of universal applica-
tion, and he has then found examples outside
of the conditions clearly specified where my
conclusions are not true. He then asserts
that this is a “ disproof" of the planetesimal
hypothesis. -
The associated alleged error is in the form-
ula expressing the final conditions under which
my conclusions are true. Dr. Lowell’s friends
will regret to learn that he has been over-
hasty in criticizing it, considering the weighty
conclusion he has hung upon his criticism.
In the first place he has not quoted it quite
correctly, and in the second place he starts
from an erroneous equation himself. Since
the linear units are not specified, the elemen-
tary principle of homogeneity of units should
have shown him that the right member of his
first equation is incorrect. Its left member is
also inexact, due apparently to an erroneous
use of the integrals of the two-body problem.
If we let p represent the mass of the satellite,
his first equation should have been the in-
equality
T-E M-L a MTſ, -— 1 = e
VH+-V*#S VIT VE
Developing and omitting the negligible terms
of higher order, we get precisely the formula
given in my book. Consequently I stand by
the conclusions reached in my book on this
subject when the conditions are satisfied
under which I have clearly stated they are
true.
Now of the planetesimal hypothesis itself,
which is much more important in the present
connection, Dr. Lowell appears really to have
a very excellent opinion, barring its tag and
signs of parentage. In his “Mars as the
Abode of Life" (1908) he says, pp. 3 and 4:
So far as thought may peer into the past, the
epic of our solar system began with a great
catastrophe. Two Suns met. . . . It is not to be
supposed that the two rovers actually struck, the
chances being against so head-on an encounter;
but the effect was as disastrous. Tides raised in
SCIENCE - 17
each by the approach tore both to fragments, the
ruptured visitant passing on and leaving a dis-
membered body behind in lieu of what had been
the other. . . . Thus, what had been a Sun Was
left alone, with its wreckage strewn about it.
Masses large and small made up its outlying
fragments, scattered through space in its vicinity,
while a shattered nucleus did it for core.
On page 6 he says:
Thus they [the meteorites] proclaim themselves
clearly fragments of some greater body. To the
sometime dismemberment of this orb, from which
disintegration our sun and planets were formed,
the little solitary bits of rock thus mutely witness.
In the Atlantic Monthly for August, 1909,
in an article entitled “The Revelation of
Evolution,” on page 177, after commenting on
and dismissing the Laplacian theory, he says,
in introducing more recent work:
Without attempting here a picture of what
probably took place, let me sketch a line or two
of its reconstruction as they have taken shape
at midnight to one watcher of the stars.
And on the following page we read:
From the information afforded us by meteorites
we turn to another discovery of recent date, the
recognition of the spiral nebulae. . . . Now, this
spectrum [that of the spiral nebulae] is just what
they should show were they flocks of meteorites—
and such they undoubtedly are. They give us,
therefore, the second chapter of the evolutionary
history. For, from their peculiar structure, we
can infer what the process was that scattered the
constituents of the once compact ball whose exist-
ence the meteorites attest. They consist of a
central core from which two spiral coils unfold,
the starting point of the one diametrically op-
posite the other. Now this is what would happen
had the original mass been tidally disrupted by a
passing tramp. Tides in its body would be raised
toward and opposite the stranger, and these would
scatter its parts outward; the motion due the
tramp combining with the body’s spin to produce
the spiral coils we see. Just as in the meteorites
we have found the substances from which our
Solar system rose, so in these nebulae we see an
evolution actually in process which may have been
OUIIſ OWI).
To those who have read the literature of the
planetesimal hypothesis as it has come forth,
stage by stage, during the past decade this will
Sound strangely familiar; and when reading
Dr. Lowell’s statements about the origin of
meteorites, one can not help but recall Pro-
fessor Chamberlin’s article in the Astrophys-
ical Journal eight years ago, “On the Possible
IFunction of Disruptive Approach in the For-
mation of Meteorites, Comets and Nebulae.”
But perhaps Dr. Lowell does not read the
Astrophysical Journal, which is edited and
published not far from the home of that
“geologist out West * who “ astronomically
is unaware that what prompted his
contention, the Planetesimal Hypothesis, is
mathematically unsound.” The Carnegie In-
stitution, however, is not so far “out West''
that it has forfeited its claim to “be treated
with respect,” and in its “Year Books '' of 1902
to 1907 are full expositions covering every
essential element that enters into the mid-
night reconstruction.
From these quotations it is clear that Dr.
Lowell has a real affection for the main fea-
tures of the planetesimal hypothesis, and if I
had not been so unfortunate as to have utterly
destroyed it (according to the new logic) by
the blunder in my book 83 pages before I took
the hypothesis up, he might almost have re-
constructed it from his own recent writings.
I am wondering whether in his forthcoming
book on “The Evolution of Worlds "* he will
* Atlantic Monthly, August, 1909, p. 181, foot-
note: “Even as this essay stood between pen and
print a geologist out west, in a long letter to
Science, has repeated, in reference to the facts
here set forth, the old attacks on Darwin for
daring to synthesize the facts; though the geologic
facts are from Sir Archibald Geikie, our own
Dana and DeLapparent, who should certainly geo-
logically be treated with respect. Astronomically
he is unaware that what prompted his contention,
the Planetesimal Hypothesis, is mathematically
unsound.”
*In the advance description of this book we
read: “So important scientifically is the work of
Professor Percival Lowell that the announcement
of a new book by him might seem to belong rather
in the list of technical works than in a catalogue
of general reading. Professor Lowell, however,
has the rare art of conveying important and new
truths in language readily intelligible to the gen-
eral reader. . . . His theme is the process by
which a world comes into existence, the phases
through which it passes. . . .”
18
not give additional proof of his affection for
the planetesimal theory, though perhaps under
some other name, or in some nameless form,
more congenial to that mysterious “watcher
THE DEVELOPMENT OF THE
WHEN, in 1906, the planetesimal hypothesis
had reached a stage of development sufficient
to warrant its introduction as a working hy-
pothesis into text-books of geology and astron-
omy, it seemed to its authors worth while to
draw up and place on their private files a
memorandum of the several stages of cos-
mogonic study that had led up to the hypoth-
esis in the form it had then taken. It was
not assumed that the hypothesis had reached
a final form, much less that it was in any
sense then proven or that it could approach
proof until after a long period of trial and the
closest scrutiny. On the contrary, they were
then engaged in further efforts to test its
working qualities and to add to its details or
to modify them. It, however, seemed worth
while at that stage to make note of preceding
steps of progress while fresh in mind for
future reference if occasion should require.
Such occasion seems now to have arisen.
In the introduction to the memorandum,
by way of qualifying the statements of the in-
dividual parts taken, it was noted that the
mutual studies of the authors had grown up
so gradually and informally, their conferences
had been so frequent and so free, and their
relations so intimate that it was difficult to
set down with accuracy the precise parts con-
tributed by each, or the aid rendered each to
the other in working these out. The memo-
randum was intended to indicate merely the
main individual lines of work and the lead-
ing stages of progress. A quite accurate and
detailed history could be worked out, if it
were worth while, from the note-books of
advanced students of the University of Chi-
cago from 1892 onward, as they were familiar
with the status these studies had reached at
the times their lecture notes were taken.
Several of these students made computations
or rendered other aid sufficient to call for
SCIENCE
of the stars ” whose scientific theories, like
Poe's visions of the raven, “ have taken shape
at midnight.”
F. R. MOULTON
PLANETESIMAL EIYPOTHESIS
notice in the papers published, among whom
were A. W. Whitney, H. L. Clarke, J. P.
Goode, H. F. Bain, S. Weidman, C. F. Tol-
man, Jr., N. M. Fenneman, C. E. Siebenthal,
R. T. Chamberlin and W. H. Emmons.
In the Synopsis below, the memorandum
of March 12, 1906, is followed in the main,
but the abbreviated phrases and references
have been rounded out or recast to make them
more specific and the whole brought down
to date.
I. DESTRUCTIVE (IN THE MAIN)
Line of Approach and First Step.–To find
out what effects on geological climates might
be assignable to changes in the constitution
of the atmosphere, Chamberlin, in the middle
nineties of the recent century, attempted to
test, by means of the molecular velocities in-
volved, after the method of Johnstone Stoney,
the probable limits to the extent of the atmos-
pheres in early geological stages, particu-
larly those conditioned by the molten and
gaseous states of the early earth as then com-
monly postulated.
These tests were found to throw doubt on
the common belief in the enormous extent of
hot vaporous atmospheres supposed to prevail
during the gaseous and molten states of the
earth. The test was then carried back to the
earth-moon ring postulated by the Laplacian
hypothesis where its application seemed fatal
to the hypothesis. Moulton aided in this test
by preparing tables of parabolic velocities for
the earth at various heights above its surface
and at different rates of rotation. Dr. A. W.
Whitney made computations relative to molec-
ular velocities under varying temperatures
and pressures. The results were set forth in a
paper read by Chamberlin at the Toronto
meeting of the British Association for the
Advancement of Science, August 20, 1897,
SCIENCE 19
and more fully in the Journal of Geology, Oc-
tober–November, 1897, pp. 653–683.
Second Step.–The conclusion that the nebu-
lous matter of the supposed earth-moon ring
could not remain in a true gaseous state, i. e.,
with the molecules in active collisional rela-
tions to one another, under the conditions
postulated for the earth-moon ring under the
Laplacian hypothesis, led Chamberlin to con-
sider the alternative conception of molecules
or particles revolving in independent orbits in
planetoidal fashion. Condensation from this
state had previously been held, generally if
not universally, to give rise to retrograde
rotations, whereas most of the rotations of the
solar system are direct. Among the more con-
venient references showing the general ac-
ceptance of this view are the following: D.
Rirkwood, Am. Jour. Sci., XXXVIII., Nov.,
1864, pp. 1–2; A. Hinricks, Am. Jour. Sci.,
XXXVII., 1864, pp. 48–52; D. Trowbridge,
Am. Jour. Sci., XXXIX., 1865, pp. 25–43; A.
Clerke, “History of Astronomy during the
Nineteenth Century,” 1893, p. 383; H. Faye,
“Sur l’Origine du Monde,” 1896, pp. 138–140,
164–171, 270–281; C. A. Young, “General
Astronomy,” 1899, pp. 568–572; Sir Robt. Ball,
“The Earth’s Beginning,” 1902, pp. 324–347;
A. Clerke, “Modern Cosmogonies,” 1905, pp.
26–42. It was therefore clear that if this
deduction were valid it was fatal to all hy-
potheses of the planetesimal type; indeed its
supposed validity was probably the reason why
such hypotheses had not been entertained.
This apparently fatal bar was removed by
Chamberlin, who pointed out that in the case
of bodies moving in elliptical orbits about a
common center, collision can only take place
when some part of the perihelion section of
the outer orbit coincides with some part of the
aphelion section of the inner orbit, and that
at the point of collision the body in the outer
orbit moves faster than the body in the inner
orbit, though on the average the body in the
larger orbit moves slower than the one in the
smaller orbit, which general fact was made the
basis of the previous adverse reasoning. The
way was thus opened for the construction of
a tenable hypothesis on the orbital basis, in-
cluding the form later called planetesimal.
This germ of constructive work on lines pre-
viously regarded as untenable was briefly
stated in the paper read before the British
Association for the Advancement of Science,
Toronto meeting, August 20, 1897, and pub-
lished in the Journal of Geology, October–
November, 1897, p. 669.
Third Step.–The tenability of construction
on an alternative line being thus assured, the
skepticism regarding the old nebular and me-
teoroidal hypotheses was more freely enter-
tained and led to a search for other tests,
particularly those resting on grounds other
than molecular activity. The discrepancy be-
tween the slow rotation of the Sun at present
and the rotation it should have if it had con-
tracted from a gaseous spheroid filling the
orbit of Mercury and having the equatorial
velocity necessary to shed the Mercurial ring
as postulated by the Laplacian hypothesis,
first came to Chamberlin’s attention and led
to a conference, with Moulton, late in 1899,
out of which grew the more systematic in-
spection of the dynamics of the solar system
in which the chief work was done by Moulton.
Fourth Step.–By restoring theoretically, in
conformity with the laws of gases, the nebu-
lous stages of the Laplacian hypothesis, com-
parisons of the Several moments of momenta
of the spheroid at these stages with the mo-
ments of momenta of the equivalent parts of
the existing system were made by Moulton
with results that seemed fatal to the Laplacian
hypothesis and to all other hypotheses which
had a similar dynamic basis. Several other
tests of a dynamical character equally adverse
to the Laplacian hypothesis were also set
forth in this paper.
Although the restorations of the solar spher-
oids at the various nebulous stages were made
on the basis of the known laws of distribution
of gases, with liberal margins of safety, uncer-
tainty as to the full trustworthiness of the
extension of the laws of gases to bodies of
such tenuity and at such temperatures was un-
avoidable. To cover doubts arising from this
* “An Attempt to Test the Nebular Hypothesis
by an Appeal to the Laws of Dynamics,” by F. R.
Moulton, Astrophysical Journal, March, 1900, pp.
103–130.
20
source, independent tests were made by Cham-
berlin on the basis of the ratios of the masses
to the moments of momenta of the spheroids
and of the separated rings, respectively, using
the masses and the moments of momenta of
the present derived bodies, thus avoiding the
application of the laws of gases; and the re-
sults were found to be equally adverse to the
Laplacian hypothesis.”
II. CoNSTRUCTIVE (IN THE MAIN)
The preceding work was chiefly destructive,
but there were three notable exceptions: (1)
The opening of the way to construction on
planetoidal lines; (2) the determination of
rather rigorous criteria that must be met in
forming a tenable hypothesis, viz., the condi-
tions must be such as to give low mass, high
moment of momentum and irregular distribu-
tion of matter to the outer part of the system,
and high mass, low moment of momentum
and sphericity to the central part; and (3)
the recognition that spiral nebulae offered the
greatest probability of meeting these criteria
and of having at the same time a planetoidal
organization.” A Summation of the leading
points made in the destructive work, together
with a statement of the constructive criteria
above named and of the grounds for giving
precedence to spiral nebulae in the search for
an origin of the solar system, was published
in SCIENCE, August 10, 1900, by Chamberlin
and Moulton jointly.
Fifth Step.–Considerable futile work was
done, largely by Chamberlin, in trying out
the possibilities of collision between nebulous
bodies as a mode of origin of spiral nebulae,
but no escape was found from the high proba-
bility, amounting almost to certainty, that the
resulting orbits would be too eccentric to fit
the case of the solar System in any instance
that was likely to occur.
Siacth Step.–The effects of the differential
* “An Attempt to Test the Nebular Hypothesis
by the Relations of Masses and Momenta,” by T.
C. Chamberlin, Jour. Geol., Vol. VIII., January–
February, 1900, pp. 58–73.
* Chamberlin in Journal of Geology, VIII.,
January–February, 1900, pp. 72–73; Moulton,
Astrophysical Journal, XI., March, 1900, p. 130.
SCIENCE
attractions exerted by bodies on one another
when they make close approaches were then
studied by Chamberlin in the lines marked
out by Roche, Maxwell and others, and found
to be a promising field for hypothesis respect-
ing the origin of meteorites, comets and neb-
ulae. This study included not merely the
direct tidal effect on a passive body, following
Roche, but also the projective effect developed
in a body of enormous elasticity already under
high pressure and affected by violent local
explosions which were subject to intensifica-
tion by the changes of gravity brought to bear
on them by a passing body. It was shown
that the contingency of close approach was
much greater than that of collision, and that
the results, (1) in the case of the disrupting
of solid bodies, afforded a felicitous basis for ex-
plaining the erratic orbits of comets, the clus-
tered fragments of the comet heads, and the
angularity of the meteorites into which they
are supposed to be finally dispersed; while (2)
the explosive projections from suns under the
influence of the passing body gave a reason
for the two-armed feature of most spiral neb-
ula—a neglected feature to which attention
was specially called—for the spiral form, for
the knots and haze, and at the same time
offered a basis for inferring their dynamical
state. These radical hypotheses were set forth
in a paper entitled “On a Possible Function
of Disruptive Approach in the Formation of
Meteorites, Comets and Nebulae,” by T. C.
Chamberlin, Astrophys. Jour., Vol. XIV.,
July, 1901, pp. 17–40; also Jour. Geol., Wol.
IV., 1901, pp. 369–393.
Seventh Step.–With these conceptions of
the origins and dynamical states of meteorites
and spiral nebulae as the bases of alternative
hypotheses, a more critical study was made of
the probabilities of origin of the solar system
from Swarms of meteorites of heterogeneous
and quasi-gaseous organization, and, more
radically, of the probabilities of the origin of
such swarms either by concentration from a
state of greater diffusion or by the dispersion
of some previous body. Conditions favorable
to the evolution of the solar system were not
found, except when the meteoric organization
SCIENCE i. 21
t
took the planetesimal form." Specifically, the
conclusion reached was that the heterogeneous
meteoritic state is “inherently moribund, pass-
ing into the gaseous state on the one hand, or
into the planetesimal on the other, or, in the
absence of assemblage, losing its constituents
to existing Suns and planets by capture One
by one.” " - -
Eighth Step.–Concurrently with these con-
structive attempts of Chamberlin with futile
results except as based on planetoidal lines,
Moulton attempted a critical review of all
recorded cosmogonic hypotheses, but unfore-
seen conditions caused the temporary suspen-
sion of work and prevented a final treatment
and publication of the assembled material."
Ninth Step.–With (1) an open door for
constructive work with nebulae of planetoidal
dynamics made available in 1897, with (2) the
controlling criteria defined, and with (3) the
limitations of tenable hypotheses narrowed by
the futile work, the planetesimal hypothesis
was gradually given shape and working form
chiefly by Chamberlin in the absence of Moul-
ton, as set forth in Year Book No. 3, Carnegie
Institution, 1904, pp. 208–233; but this shaping
of the hypothesis passed under the criticism
of Moulton before publication. The spirit
and purpose of this constructive work is thus
stated, pp. 232—233:
It has thus been my endeavor to develop the
hypothesis into sufficient detail (1) to furnish a
large number of points of contact with known
phenomena and with recognized mechanical prin-
ciples to facilitate testing its verity by those
relations, if not now, at least in the early progress
* Chamberlin in Year Book No. 3, Carnegie
Institution of Washington, 1904, pp. 195—208.
*Ibid., p. 208.
"Moulton in Year Book No. 3, Carnegie Insti-
tution, 1904, pp. 255–256.
of investigation; (2) to furnish a basis for de-
ducing the hypothetical stages of the earth that
preceded its known history, and for drawing
thence inferences as to the conditions of the in-
terior which the earth inherited from the mode
of its birth; and (3) to stimulate inquiry into the
elements involved. In short, I have endeavored
to give the hypothesis a working form under the
conviction that so long as the complicated ele-
ments involved remain so imperfectly determined
as at present its working value is its chief value.
|Preliminary to this publication the essen-
tial features of the hypothesis had been dis-
cussed before several scientific societies and
Subjected to criticism. The hypothesis was
also set forth by Moulton in a paper “On the
IEvolution of the Solar System,” Astrophys.
Jour., October, 1905, pp. 165–181.
Later Steps.-The hypothesis was somewhat
further elaborated and supplied with illustra-
tions for text-book use by Chamberlin for the
chapter on the Origin of the Earth in Cham-
berlin and Salisbury’s “Geology,” Vol. II.,
Chap. I., pp. 28–81, 1905, and by Moulton for
his “Introduction to Astronomy,” 1906, pp.
463–487.
Subsequent work in further testing, devel-
oping and applying the hypothesis has been in
progress as set forth in Year Book No. 4,
Carnegie Institution, 1905, pp. 171–173
(Chamberlin), and 186–190 (Moulton); Year
Book No. 5, Carnegie Institution, 1906, pp.
165–172, and in later Year Books. More
Specifically and concretely, the continuation of
investigation on lines growing out of the
planetesimal hypothesis is shown by Publica-
tion No. 107, of the Carnegie Institution, en-
titled “ The Tidal and Other Problems.”
T. C. CHAMBERLIN
F. R. MOULTON
CFIICAGO,
October 14, 1909
|GAN
CH
UNIVERSITY OF M!
|
|
|
|
|
|
|
|
|
57;）;
（***）
ᤤ

!:4. -
º
º
:
{
; :
{ .
* *
g
t
i
! .
t
f
i
~~~~…~:
* ...º.º.
* **
º