I Hope you will be pleased to excuse the liberty, which I take, of
troubling you with my observations on the comet, which made its
appearance here, and in other parts of Europe, in the months of
September and October last; and which, according to the news-papers,
was first observed the 11th September by Mr. Gartner, at Dorlkeurtz
near Dresden; then, by me, on the 16th of the said Month, here in the
Hague; and afterwards in different places. As I find, that you have
observed the comet, I doubt not but that you have done it in the most
accurate manner; and my great love for this science induces me to beg,
that I may have the happiness of knowing some of your observations.
My good friend Mr. Struyk at Amsterdam wrote me some time ago, that
he intended to ask the same favour of you; but I have not since heard
any further from him. I observed this comet from Septemb. 16th in
the morning, until Octob. the 11th in the morning; and found its
situations, according to my method, as follows:
_Longit._ _Latit._
1757. ° ´ ° ´
Sept. 16. at 4 h. ante mer. The comet in ♋ 10 15 with 10 10 North.
17 -- 3 -- -- -- -- -- ♋ 14 7 ---- 9 38
18 -- 3¾ -- -- -- -- -- ♋ 18 10 ---- 8 57
19 -- 4 -- -- -- -- -- ♋ 22 1 ---- 8 17
22 -- 2¾ -- -- -- -- -- ♌ 3 46 ---- 6 15
23 -- 4 -- -- -- -- -- ♌ 7 36 ---- 5 24
25 -- 4¼ -- -- -- -- -- ♌ 14 50 ---- 4 6
28 -- 4 -- -- -- -- -- ♌ 24 22 ---- 1 41
Oct. 1 -- 4¾ -- -- -- -- -- ♍ 2 46 ---- 0 12 South.
4 -- 4½ -- -- -- -- -- ♍ 9 45 ---- 1 30
9 -- 4½ -- -- -- -- -- ♍ 20 20 ---- 2 40
11 -- 5 -- -- -- -- -- ♍ 24 46 ---- 3 9
But the two last observations will, in my opinion, differ the most;
because, when I made them, I was in some doubt about the adjustment
of my instruments; and the comet was then far advanced into the
morning rays. I have, since the month of February last to the end of
May, made sundry observations on fixed stars, with a telescope of 16
inches, made by Mr. Short; and with a pendulum clock, made after the
manner of Mr. Graham, by Mr. Vryhthoff of this place. In the months
of February and March, by a medium of eight observations, I found,
that by the clock, the star Rigel, in every daily revolution, passed
4 min. 2⁴⁄₉ seconds of time earlier, in the telescope; and in the
latter end of May I found, by six observations, (the clock not in the
least changed or altered) on the star Spica Virginis, that that star,
in every revolution, passed 4 min. 5¹⁄₂₀ sec. earlier, in the same
telescope; which intervals differ pretty nearly 2⅗ seconds of time from
one another. Whether this difference arises from any defect in the
clock, or whether it proceeds from any small difference of velocity
of the earth’s motion round its axis, I would have been very glad to
have endeavoured to find out by farther inquiry, had not the death of
Mr. S. Koenig intervened, and I thereby hindered from continuing my
observations. The above observations were taken in the observatory of
his illustrious Highness the minor Prince of Orange and Nassau, _&c.
&c._ under the direction, and with the approbation of the aforesaid
Mr. Koenig. After the death of that gentleman, I petitioned her Royal
Highness the Princess Governess of these Provinces, _&c._ that I might
have leave to continue my astronomical observations; but as yet I have
not been able to obtain her Royal Highness’s permission: otherwise I
would have observed this last comet with more exactness. Had I been
able to pursue the above-mentioned observations, I would, for the
greater certainty in regard to the pendulum, have made use of a farther
precaution. By means of a stove, with the help of a thermometer, I
would have endeavoured to have kept the room (in which the clock stood)
in the winter, and at all times, in the same degree of heat it had at
the time I made the observations in the summer. I would also have daily
observed and noted the moon’s place, at the time of the observations.
Tho’ this is but a slight observation of mine; yet I make no doubt, but
that in case, by the different distances of the earth from the sun,
and the different distances and situations of the moon with respect
to the earth, and the respective effects produced by these causes,
any inequality arises in the velocity of the diurnal motion of the
earth on its axis, you (who have made the most sublime observations on
the aberration of the fixed stars, and more than any mortal ever did
before) must have discovered, and are well acquainted, with the same.
As my above-mentioned observations on the comet appeared too incorrect
to undertake a calculation for the ascertaining of its path from the
theory, I contented myself with effecting it by a construction. By this
means I found, on a figure, whose globular or spherical diameter was
13½ Rhineland inches, as follows:
That the comet was in its perihelion the 21st of October, at two of the
clock in the afternoon: the place of the perihelion 3 degrees in Leo.
The comet’s distance in the perihelion from the sun was about 34 parts,
whereof 100 make the mean distance between the sun and the earth. The
inclination of the comet’s orbit with the ecliptic 13 degrees; and the
southern latitude of the perihelion also 13 decrees: the ascending or
north node ☊ 4⅓ degrees in Scorpio; and the comet’s motion direct, or
according to the order of the signs of the zodiac. On this supposition
I have, for some of the times of observations, estimated the apparent
places of the comet, and found them as follows:
_Long._ _Latit._
Sept. 18, at 3¾ ante merid. In ♋ 18¹⁄₁₂ and 9 deg. North.
19 -- 4 -- -- -- ♋ 22 ---- 8⅖
22 -- 2¾ -- -- -- ♌ 3⅝ ---- 6¼
23 -- 4 -- -- -- ♌ 7⅗ ---- 5½
25 -- 4¼ -- -- -- ♌ 14⅔ ---- 4
28 -- 4 -- -- -- ♌ 24⅓ ---- 1¾
Oct. 4 -- 4½ -- -- -- ♍ 9⅓ ---- 2 ---- South.
9 -- 4¾ -- -- -- ♍ 19⅔ ---- 3⅖
11 -- 5 -- -- -- ♍ 23⅛ ---- 3⅘
The observations, which I have taken, to ground the measurement on, are
those of the 16th and 23d of September, and of the 1st of October. It
appears very evident, not only from this rough calculation, but every
other circumstance of this comet, that it is not the same with that
in the year 1682: which, on certain accounts, is very desirable to be
known; for both here, and in other parts of the Netherlands, there
have been some people, who have published mere conjectures; and have
ventured (very minutely and exactly, as they pretended) about the time
that this comet first made its appearance, to predict the return of
the comet of the year 1682. But by the above, the weakness of their
pretensions is very evident to all the world: whereas, if this had
proved to be the expected comet, they would have assumed to themselves
much undue praise, and have pretended to knowlege even superior to the
every-where much celebrated Newton and Halley.
It appears also probable to me, that this comet is none of those
already calculated, or brought upon a list, by Messieurs Halley and
Struyk. It is somewhat remarkable, that the line of the nodes is
almost at right angles with the long axis of the ellipsis; which
corresponds nearly with the comets of the years 1580, 1683, and 1686:
but those had their perihelions northward of the ecliptic; whereas the
perihelion of the last, which we have lately seen, was to the southward
of the ecliptic.
I have the honour to subscribe myself, with the most perfect esteem for
you, and your sublime studies, very respectfully,
SIR,
Your very humble and obedient Servant,
D. Klinkenberg.
Hague, 13th Dec. 1757.
LXI. _Remarks on the different Temperature of the Air at_ Edystone,
_from that observed at_ Plymouth, _between the 7th and 14th of_ July
1757. _By Mr._ John Smeaton, _F.R.S._
[Read Jan. 12, 1758.]