258 
SCIENCE 
SWIFT’S COMET. 
The comet discovered by Swift on the 10th of October 
last, has again attracted general attention from the an- 
nouncement by Mr. Chandler in Special Circular No. 7, 
to Science Observer, that it seems to be identical with 
Comet III., 1869 (Tempel), and from the announcement 
by the Astronomer Royal to the Smithsonian Institution, 
of a comet discovered by Lohse, at Lord Lindsay’s ob- 
servatory, Dun Echt, November 7, which proves to be 
an independent discovery of the same object. It has 
already been followed for nearly a month by astronomers 
in America, and its elements were computed by Mr. 
Chandler as accurately as possible from the data at 
hand. 
The following observations made by Prof. Eastman 
with the Transit Circle of the Naval Observatory, Wash- 
ington, together with the resulting elements and ephem- 
eris computed by Mr. Upton, have been kindly fur- 
nished for publication. 
COMET, SWIFT, 1880. 
Observations made with the Transit Circle at the 
Naval Observatory, Washington, D. C. : 
R. A. Decl. 
H. M. S. + 28° 29' 4". 9 
October 25. 21 50 8.74 35 0 32' 48". 1 
November 1 — 22 12 33.12 42 0 26' 8". 3 
L 7 22 45 6.26 
ELEMENTS. 
^=1880. Nov. 8.00411, Wash. M. T. 
7T= 4 2 ° 2 7 13 "] 
£2 = 295 48 23 vMeanEq. t88o.o. 
I — 7 22 !6 
log. q=o. 04220. 
COMPUTATION OF MIDDLE PLACE. 
Obs. Comp. 
dACosp = —15" 
d fi = +4 " 
It presents an ill-defined disc, several minutes in diam- 
eter, but owing to the brightness of the moon, it can be 
seen for the next week, only with the larger instruments. 
It the identity of these two comets is finally established, 
and there seems to be no reasonable doubt of it now, a 
recomputation of the elements, embodying all the reliable 
observations made in 1869, will be very desirable, and 
will doubtless soon be undertaken. W. C. W. 
Washington, Nov . 15, 1880. 

THE NEW PERIODIC COMET. 
This comet, discovered by me at midnight of October 
io-n,is destined, from present indications, to become 
one of considerable celebrity, notwithstanding it will not 
be visible to the naked eye. The computation of the ele- 
ments of its orbit reveals the fact that they are almost iden- 
tical with those of Comet III., 1869, and hence it becomes 
what in astronomical language is called a periodic comet. 
This will have a period of not over 1 1, and probably only 
5)4 years, in which case it must have returned unob- 
served to perihelion about the middle of the year 1875.. 
In either case it will be a periodic comet of short period. 
1 am indebted to the kindness of Prof. S. C. Chandler, 
Jr., of Boston, for the following set of elements, which, 
however, owing to the inexact determinations of the three 
positions used for their computation, must, of course, be 
considered only as approximations. They are, no doubt, 
near enough to the truth to establish the fact that Comet 
IV., 1880, is a return of Comet III., 1869, for it is 
almost an impossibility for two different comets to come 
into our system possessing physical characteristics so 
similar, and having elements so nearly alike. I copy 
both sets of elements for comparison : 
Comet III., 1869. Comet IV., 1880. 
Per. passage. Nov. 20.854. Nov. 7.714. 
Lon. per 41 17 12.5 41 41 
Lon. node 292 40 28.8 295 25.4 
1 6 55 o 7 21.7 
Log. q 0.042416 0.04262 
Motion. Direct. Direct. 
EPHEMER 1 S. WASHINGTON MEAN MIDNIGHT. 
Date. 
R. A 
Decl. 
Intensity 
of 
Light. | 
H 
M. 
s. 
1880 — November 16.- 
0 
13 
15 
+ 52 0 
8' .7 
1. n 
20.- — 
I 
7 
41 
54 
3 1 - 2 
1.08 
“ 2 4 
2 
5 
44 
54 
59.0 
0.99 
“ 28 
2 
59 
22 
53 
38.8 
0.86 
December 2 
3 
43 
26 
5i 
2 -5 
0.72 
44 6 - 
4 
17 
21 
47 
50-5 
0.58 
In order to show the remarkable accordance with the 
elements of III., 1869, we give the elements of this latter 
comet as published by Dr. Bruhns, Astron. Nach. I788: 
COMET III., 1869. 
’I- 1 =: 1869, Nov. 20. 85426. Berlin, M. T. 
T = 41 0 17' 12". 5 | 
= 292° 40' 28". 8 C Mean Eq. 1870.0 
l = 6° 55' o".o J 
log. q. = 0.042416. 
Assuming the two to be identical, and the comet to 
move in an eclipse having a period of 12 days less than 
1 1 years, we shall have— 
Semi-major axis = 4.93589 
Eccentricity = 0.7767. 
The intensity of light on November 7 is taken as unity. 
On this scale the intensity on October 10, when the 
comet was discovered, was 0.36. It reaches a maximum 
brightness about November 16, and it is probable that 
observations can be continued till near the end of the 
year, before the comet becomes too faint. 
If the above supposition regarding the identity of the two 
comets be true, it will add another to the list of periodic 
comets, bringing the number up to eleven. Their names 
are as follows : 
Name. 
Halley’s 
Encke’s 
Winneckes 
Brorsen’s 
Biela’s 
D’Arrest’s 
Tempel's (1867) 
Tempel’s ( 1873) 
Faye's 
Tuttle’s 
Period. 
76.75 years. 
3 - 3 ° " 
5-54 “ 
558 
6.61 
6.64 
6.00 
S-i6 
7-44 
13.66 
From the above list 1 have rejected De Vico’s comet, 
which should not have been placed there, as the sup- 
posed periodicity has never been verified by an observed 
return. 
There can be but little doubt that to this list should be 
added comet I, 1880, commonly called the great South 
American comet, with elements and general appearance 
almost identical with the great comet of 1843, one of the 
most remarkable comets mentioned in history. It was 
seen in the daytime, close to the sun’s limb, glowing like 
a coal of fire. Of all known comets, it has made the 
nearest approach to the sun. It was truly said of it : “ It 
exhausted its head in the manufacture of its tail,” for it 
was nearly all tail. 
As an evidence of the advance which cometary astron- 
omy has made in our times, it may be stated that up to 
1822 one only, (Halley’s) periodic comet, was known. 
The number of such is doubtless very great, in fact com- 
putation makes the number several hundred, but until 
