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Two lectures on comets online

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" year 1774, a royal mandate was issued to nega-
" live three gentlemen who had been most active in
'* opposing the measures of the administration ; these
*^ were Mr. Roivdoin^ Mr. Dexter and Mr. Winthrofi.'^^

These respectable gentlemen were not intimidated,
nor did they consider themselves degraded, by this
royal frown. We learn from Professor Wiggles-
worth, the elevated sentiments with v/hich it w^as re-
ceived by Dr. Winthrop. Mr. Bowdoin was raised
to the chuir of government, after his country, whose
rights he had so ably advocated, had gained its inde-
pendence. He had then to experience the uncertain
continuance of public favour j but he still enjoyed the
precious consciousness of pure intention, and ail that
estimation, which the wise and virtuous hold most

In popular impulse, as well as in cabinet devices.,
there is sometimes an obliquity-^to which such men
cannot be made to accommodate. A rectitude, which
should command admiration, frequently renders them
victims to political intolerance ; denunciation and ex-
cluiion from ofhce in such cases, can be no reproach
to their characters, and«- seldom permanently injuri-
ous to the cause which they espouse.

Yirtiis repulsse nescia sordidae
Intaminatis fulget honoribus,

* Bioff. Dint.


When the royal control which had rejected Dr.Wm-
throp was at an end, he was re -chosen into the coun-i
oil. In this difficult and responsible station he re-
mained during a period eminently critical and trying.
He was also appointed Judge of Probate for the county
of Middlesex ; which office he held urstil his decease,

" The best part of Dr. Winthrop's character," says
Dr. Eliot, " was, that he was a Christian philosopher.
" He believed the truths of Christianity from study
'< and conviction, and was an ornament to his profes-
^' sion. To his numerous acquaintance he was a
^' friend, philosopher, and guide." " In frequent
'* and distressing sickness," says Dr. Wigglesworth,
" no complaint ever came from his lips. He sup-
" ported himself v^ith a manly fortitude and a sober se-
** renity, which Christianity alone could inspire.'' He
died May 3, 1779, aged 65.

The discourses delivered by President Langdon,
Professor Wigglesworth, and the Rev. Dr. Howard,
occasioned by the death of Dr. Winthrop, all express
his emphatic testimony to the truth of the gospel,
made biiiFawc the da^<fe*his departure.

" I view religion as a matter of very great impor-
" tance. The wise men of antiquity set themselves
" to work to prove the reality of a future state. They
*« catched at every thing which had the shadow of
" probability. They gave a degree of plausibility
" to the argument. They were sensible of the need
•' they stood in of such a doctrine. In opposition to
" the wise men of antiquity, the wise men of modern
" times have employed their abilities in undermining


" every argument in favour of immortality, and ia
" weakening the only hope that can sustain us. But
" the light thrown on this matter by the glorious gos-
" pel, with me amounts to demonsiration. The hope
" that is set before us in the New Testament is the
" only thing which will support a man in his dying
« hour. If any man builds on any other foundation;,
" in my apprehension his foundation will fail."

In his writings also will be found decisive marks of
a religious turn of mind, and of a settled disposition
to direct philosophy to the noble objects, emphatically
expressed by Bacon, " the glory of the Creator and
the good of man's estate."

The following lines, published anonymously at the
close of Professor Wigglesworth's Discourse, are un-
derstood to have been written by Andrew Oliver, Esq.



Ye Sons of Harvard ! who by Wlnthrofi taught,
Can travel round each planetary sphere ;
And, wing'd with his rapidity of thought.
Trace all the movements of the rolling year ;
Drop on his urn the tribute of a tear.


Ye, whom the love of Geometry inspired,
To chase coy Science through each wincUn^ maze j
Whose breasts were with Newtonian ardor fir'd,
Catch'd by his sparks, and kindled at his blaze :
In grateful sighs, ejaculate his praise.

Ye philosophic souls ! whose thoughts can trace
The wonders of the architect divine.
Through depths beneath — o*er nature's verdant face.
Where meteors play— where constellations shine ;
Heave the deep groan — and mix your tears with mine.

Ye tenants of the happy seats above !
Welcome this late inhabitant of clay,
From hostile factions, to the realms of love,
Where he may bask in everlasting day.
Ye kindred spirits waft him in his way.

When in their sockets, suns shall blaze their last;
Their fuel wasted, and extinct their light:
And worlds, torn piecemeal by the final blasts
Subside in chaos and eternal night i

He still shall shine

In youth divine,
And soaring on cherubic wing,
Shall like an ardent Seraph blaze,
And in unceasing raptures, to his maker's praise^
Eternal Hallelujahs sing.




Andrew Oliver, Esq. author of the Essay on Com
metSi was born in Boston, A. D. 1731. He was the
eldest son of Andrew Oliver, Esq. Secretary of the
Province, and afterward Lieutenant Governor. He
was educated at Harvard College, and received his
first degree in the year 1749. Having married a
daughter of the Hon. Judge Lynde, he was induced
to remove to Salem. He was a man of genius, and
distinguished for his philosophical researches. His
circumstances v/ere such that a life of business was
not necessary for his support ; and he was able to in-
dulge, without impediment, his prevailing love of lite-
rature and science. Besides the Essay on Comets, he
wrote an elaborate paper on Thunder Siorms^ and ano-
ther on Water S/iouts, which were published in the
second volume of the Transactions of the American
Philosophical Society : Of that Society he was a mem-
ber, and one of the original members of the American
Ac:\demv of Arts and Sciences.


This gentleman wasnotonly a proficient in Natural
or Experimental Philosophy, but was well skilled in
Geometry, and other branches of Mathematics. He
was fond of music, and studied it theoretically, and
occasionally indulged a taste for poetry ; but except-
ing his Elegy on the death of Dr. Winthrop, we are
possessed of none of his poetic performances, though
several are said to have been published. He was also
particularly attached to history, which was the prin-
cipal solace of his leisure hours, when free from the
pain of a chronic disease, with which he was afflicted
for more than thirty years of his life. He occasion-
ally amused himself, like the sagacious Dr. Wal-
lis, and many other men of scrutinizing minds, with
deciphering. In this he became such a proficient,
that it has been observed, he never met with a cipher
which eluded his research.

His studious habits, as well as his state of health,
-induced a life of much seclusion from general society:
Yet there was no asperity or gloom in his composition.
In his temper and disposition he was cheerful, affa-
ble, and benevolent ; ever ready to listen to the voice
of distress, and promptly to administer relief. He
was a Judge of the Court of Common Pleas, in the
county of Essex, before the revolution : and was ap-
pointed one of the Mandamus Counsellors in 1774.
The office had been unsolicited on his part, and he
was the first to resign it. He was a friend to free in-
quiry in religion and in politics, and a believer in the
doctrines of Christianity. After a long and paiiifui
sickness, which he sustained with singular equuiiimity
and resignation, he died at Salem, in 1799, aged 68,


Mr. Oliver's Essay on Comets was published in
1772. It has ever been considered a very ingenious
and respectable performance by intelligent men in
this country, and was well received abroad. It was
translated into the French language at Paris. M.
Bailly, the celebrated and unfortunate author of the
History of Astronomy, makes respectful mention of
Mr. Oliver's conjectures and reasonings. He notices
a correspondence between his ideas of repulsion, and
an opinion of Buffon's relative to the cause of the
expansion of fire and light, and after giving an analy-
sis of the contents of the Essay, concludes with this
observation. " The whole of this work is extremely
" ingenious — the system is highly probable ; more
" than this should perhaps be said of the application
" of a repulsive force, and of electric phenomena, to
" the appearances of the tails of Comets."*

Mr. De Luc, in the Journal De Physique, 1802,
after combating a supposition of Louis Bertrand, that
Comets are designed to produce periodic displace-
ments of the ocean for the renewal of the terrestrial
continents, suggests a scheme of their constitution and
use, in a great degree conformable to Mr. Oliver's
system, both in outline and in explanations.

* " Tout cet ouvrage est infiniment ingenieux ; le systeme
**esttres-vraisemblable ; et peutetre I' apphcation de la force
"repulsive et des phenomenes electriques aux phenomenesde
kL** la queue des cometes merite-t-eile un autre nom." And again,
«< II semble quil n'y ail rien a repondre a 1' application que
**Pauteurfait des experiences de M. Franklin."


The physical constitution of these bodies, their des-
tination and use, are among the arcana of nature.
Every new appearance of a Comet revives discussion
on their dubious phenomena, and suggests inquiries^
of difficult solution. To all who may contemplate the
subject, Mr. Oliver's Essay will be an acceptable aid ;
and if the great question attempted to be solved, should
still be thought doubtful, the reader will find his at-
tention rew^arded by a valuable collection of facts, and
an ingenious display of philosophical reasoning in
their application.


Dr. Winthrop was among the earliest members of the Ame-
rican Philosophical Society ; and one of the Corporation of
Harvard College, from 1765, until his death. He was twice
married. His first wife died in 1753. The second survived
him, and died, a widow, 1790. They were both amiable and
accomplished women. He had five sons, all from the first mar-
riage Two of them are now living; the Hon. James Win-
throp, and Hon. William Winthrop, both of Cambridge. The
Cogitata de Cometis were inserted in the Transactions of the
Rojal Society, 1767, and not published separately A few co-
pies only, were separately prmted for the author's use.


p xiii, line 21, for bujusque, read hucusque. p. xv, 6 lines
from Ihe top, in some copies, i'ov 145, read 45. p. xv, in the
note, line 1, for datCy read data. p. xviii, line 4, from tjie bot-
tom, for is, read are. p. x»x, line 22, for before the day of his
departure, read the day before his departure p. 168. line 15, for
90,505,932, reail 95,505,932. p. 188, line 4, from bottom, for
s per Of read assero.









Hollisian Professor of the Mathewatifs and Philosophy at Cambridge.





A HE appearance of tbe Comet, with which our
heaven is now adorned, has induced me to quit
at present the subject we were considering in the
course of these lectures, in order to lay before you
some account of this extraordinary sort of bodies,
which in all ages have commanded the attention of
mankind. In treating which subject, I shall first briefly
examine the principal hypotheses that have prevailed
concerning Comets, and then explain more largely
the true theory of them, according to the latest dis-

Every one knows that there are two^ sorts of stars
commonly to be seen in the heavens ; some, move-
able; others, immoveable. The immoveable ones,
generally called ^a-^c/ stars, have this title on account
of their retaining invariably the same distances from,
and positions towards each other. The movepible ones
are called Planets, from the greek word t^Xu.nirr.q-t
which signifies a ivajidcrmg star; because they are
perpetually changing tlieir ph^ces with regard to the
fixed stars, and to one another. Both of them shine,
\vhen the air is clear, with a brisk and vivid light.


The Comets are a third sort of stars ; moveable like
the planets, but greatly differing in several particu-
lars from them, as well as from the fixed stars. The
bodies of them usually appear different from all the
other stars ; being of a dull and dusky light, like that
of a star shining through a thin cloud. They are in-
compassed with an haziness, called their atmosphere,
which generally appears much larger than the body,
or, as it is otherwise called, the nucleus or head of the
Comet. But what most remarkably distinguishes
them from the rest of the stars is their tally which is
a train of pale light, extended from their atmosphere,
sometimes to very great lengths. From an imagined
resemblance of this to hair^ a star of this sort was
termed in greek ^^^jjtjjs, that is, an hairy star; which
was the original of our word Comet. The matter of
which this tail consists is so extremely rare, that the
smallest stars appear through it without any diminu-
tion of their lustre. When the tail is of a consider-
able length, it has a sensible curvature, convex on
that side to which the Comet is moving; but if it be
short, this curvature is scarcely perceived. It is ge-
nerally broader towards the end than near the head
of the Comet, and of a fainter light; and its direc-
tion is opposite to the sun ; — not exactly so indeed,
but deviating a little that way from which the Comet
has moved. Sometimes it is bifurcated, like two
branches proceeding from one stem. It sometimes
appears to go before the head of the Comet, and
sometimes to follow it; and sometimes to surround it
on all sides. The apparent courses of Comets also


cUifer very much from the planetary ones. The pla-
nets never depart far from theeclipuc; whereas Co-
mets range through all parts of the heavens. And
as they make their first appearance indifferently 'in
any constellation, though most conmionly within 90^
of the sun, or in some part of that hemisphere which
has the sun in the middle of it ; so they move indif-
ferently any way, either from south to north, or from
north to south ; and sometimes are seen to run off
even to the very poles. In one particular indeed,
their motions agree with those of the planets. For
as the planets are sometimes seen to proceed with a
direct motion, or from west to east, and then, in other
aspects with the sun, to be retrograde^ or go back-
wards from east to west; so have several Com.ets,
whose motion was at first direct, become afterwards
retrograde; and others have altered their course from
retrograde to direct. Comets are not always to be
seen, as the planets are ; but only occasionally, and
after uncertain intervals of time. Sometimes several
have been discovered within the compass of a few
years ; but for the most part, their appearances havQ
not been so frequent. They are seen but a little
while, only for a few weeks, or months at most ; and
though when they first shew themselves, some of
them are bright and large, equal in apparent diame-
ter to Jupiter and V'enus, and almost the * moon it-
self; yet they are commonly observed to diminish in

* As the Comet of 1652. Hevelil Cometogr. Lib. vl. p.



magnitude, in brightness, and in the length of their
tail, until they become quite invisible. Such are the
general phoenomena of Comets ; and these the tests,
by which every hypothesis concerning them is to be

A variety of opinions hath been entertained, as to
the nature and place of these bodies. Some have
looked upon them to be worlds on fire ;* and some,
nothing more than lucid meteors : and while many
have confined them within the narrow limits of our
atmosphere, others have raised them up to the fixed
stars. So widely do men differ, when, instead of
searching into the nature of things, they indulge
their own imaginations.

It was an ancient doctrine of some Pythagorean
philosophers,^ that the Comets are a peculiar kind of
wandering stars; that they are to be reckoned among
the permanent bodies of the universe; that they move
in their proper orbits, completing their courses in
stat-ed times : but that they are visible only in a small
part of their orbits, and return not again till after a long
period of years; being too remote, during the great-
est part of their revolution, to be discerned by us.
But the Perij[iatetic scheme afterward prevailing, the
philosophers of that sect, who held that the heavens
are absolutely immutable and incapable of generations
and corruptions, regarded the Comets, not as stand-

* Wlilch seems to be the idea conveyed by our vulgar term
f Grcgorii Astron. Lib. v. Sect. i.


ing works of nature, but as new productions which
quickly perish ; and maintained them to be only a kind
of meteors formed out of the exhalations of our at-
mosphere, and much below the moon; being appre-
hensive that, if they were placed higher, their ap-
pearing and disappearing so uncertainly would divest
the heavenly region of that privilege of immutability
which they had assigned it. In this they were con-
firmed by another notion they had taken up, that the
planets were carried round in their courses by solid
crystal orbs ; through which, to be sure, the Comets
could not penetrate. Thus does one error lead to
another. And by the way, the prevalance of this
opinion has had an ill effect, and has been the true
reason why this most curious part of astronomy,
v^'hich relates to Comets, lay uncultivated for so many
ages; the philosophers, who had imbibed such
notions, thinking it to no purpose to describe with
accuracy the irregular motions of such vanishing va-
pors. Had the ancients observed the paths of Co-
mets among the fixed stars with the same care as they
did those of the planets, the astronomy of Comets
had, in all probability, by this time been brought to
almost the same perfection with that of the planets.
But as the opinion, that the Comets were meteors
and below the moon, obtained for many ages almost
universally, and was the only one publicly taught till
the time of Tycho Brake, an eminent astronomer
of the sixteenth century, it has hence come to pass,
that we have nothing certain transmitted to us, of the
motion of any Comet, till within these last 200 years;


those which appeared before, having not been de- -
scribed by astronomers, but only mentioned by histo-
rians as prodigies, or omens of dreadful calamities.
But Tycho, having carefully observed a remarkable
Comet, found by repeated trials, that it was not sub-
ject to a diurnal parallax; for it appeared at the same
time in the same place among the fixed stars, to two
observers at the distance of several hundred miles
from each other. This observation at once overthrew
trie doctrine of the schools, and placed the Comet far
above the moon. The astronomers, who came after
Tycho, having diligently watched the Comets which
appeared in their days, have found that the diurnal
parallax of all of them is either wholly imperceptible,
or extremely small ; — a demonstration, that Comets
cannot be serial meteors, but ought to be ranked
amongst the heavenly bodies. Indeed, their partak-
ing of the apparent diurnal motion of the heavens
might have taught those philosophers better, and was
a sufficient indication that Comets are not appendages
of the earth.

As the want or smallness of a diurnal parallax has
raised Comets above the moon, so from their being sub-
ject to an annual parallax it is certain that they are not
among the fixed stars, but descend into the region of
ihe planets. Though they are at too great a distance
lo have their apparent place altered by being viewed
from different parts of the earth, yet they come near
enough to have it altered by being viewed from differ-
ent parts of our annual orbit. Accordingly, their ap-


parent motion is sensibly affected by the annual mo-
tion of the earth, in the same manner as that of the
planets is. The real motion of all the planets round
the sun is constantly direct, or from west to east ;
and not very unequal in the several parts of their or-
bits ; and would appear to be so, if viewed from the
sun, which is fixed in the centre of their orbits; but
their apparent motion, as viewed from the earth,
which moves the same way as they do, is very various.
Sometimes they are seen to go swifter, sometimes
slower, with a direct motion ; then to be retrograde,
going the contrary way, or from east to west ; and be-
tween these opposite motions, they appear for a little
while stationary, or without any motion at all. These
appearances depend on the motion of the earth, as
that happens to conspire with, or be contrary to, and
to be swifter or slower than, the real motion of the
planets. And for the same reason must the apparent
motion of Comets be changed, if they move within
the planetary orbs. Those, whose real motion is di-
rect, will appear stationary and retrograde, or at least
much slower, in nearly the same aspects with the sun,
as the planets appear so ; but those, w^iose real mo-
tion is retrograde (for such is the motion of some Co-
mets) will, in the same aspects, appear stationary and
direct. And conversely, since this is the case in factj*
since the visible motion of Comets is altered, as the
earth's annual motion would require on the supposi-
tion of their coming into the region of the planets, it

* See before, p. 3.


follows, that they do come mto the region of the pla-
nets. Thus, by the way, the Comets supply us with
a new proof, that the earth revolves round the sun ;
for without supposing this revolution, their motions
cannot be reduced to any sort of regularity. So far
indeed are Comets from being among the fixed stars,
that it appears from their annual parallax, that they are
seldom seen till they come within the orb of Jupiter,*
and that they frequently descend below the orbs of
Mars and the inferior planets.

Some astronomers, who had rightly placed Comets
in the region of the planets, have been mistaken in
their thoughts on the constitution of these bodies. It
has been supposed, that Comets were formed by the
coalition of some subtle exhalations from the planets ;
and that they were, with regard to the sun, of the
same nature as what are called shooting stars, with
regard to the earth. But this opinion is overthrown
by what Sir Isaac Newton has observedf of the re-
markable Comet which appeared in the year 1680.
The earth is above 160 times farther from the sun,
than that Comet was in its perihelion. Now the heat
of the sun, being as the density of the rays, is in
every place reciprocally as the square of the distance
of that place from the sun ; and therefore, the heat
of the sun at the Comet in its perihelion was above
26000 times greater than it is at the earth. But
the heat of boiling water is about three times as
great as that which dry earth contracts from the

* Newtoni Principia, p. 480. f Piincip. p. 508,


summer sun ; and so the heat at the Comet was
about 9000 times greater than that of boiling water.
And the heat of red-hot iron Sir Isaac conjectures
to be about three or four times greater than that of
boiling water; wherefore the heat, which dry earth
on the Comet in its perihelion might contract from
the rays of the sun, was about 2000 times greater
than that of red-hot iron. But by so intense an heat
as this, all volatile matter must presently have been
consumed and dissipated ; and the Comet, which
could endure this most violent heat, certainly did not
consist of vapors or exhalations of any kind.

Different conjectures have been proposed to ac-
count for that peculiar phcenomenon of Comets, their
tails. That these depend in some manner on the sun,^
is plain from their perpetually pointing to the part
opposite to the sun ; as hath been observed of all the
Comets within these last 200 years. This, in the

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Online LibraryJohn WinthropTwo lectures on comets → online text (page 2 of 14)