610 
OUR ASTRONOMICAL COLUMN 
THE VARIABLE-STAR V CyGni.—In Dr. Hartwig’s ephemeris 
of the variable stars for the present year a maximum of V Cygni 
is doubtfully assigned to November 15. The change in the 
brightness of this strikingly red star was notified by the late Mr. 
Birmingham iv May, 1881. The several determinations of the 
time of maximum in the following year were very discordant ; 
thus, Dr. Lindemann (who made an interesting communication on 
this star to the St. Petersburg Academy in January 1884) fixed it 
on August 31 ‘‘ auf wenige Tage sicher” ; Schmidt gave July 17, 
while Prof. Safarik considered it was reached on June 17. This 
divergence induced Dr. Lindemann to commence regular 
observations of the star in August 1882, details of which 
will be found in his paper (Bulletin de 1’ Academie Imperial 
des Sciences de St. FPétersburg, t. xxix.). The variation 
appeared to be from 6°8 m. to below 10 m., and the period 
indicated by the observations of 1882 and 1883 was about 
a year, though a longer one is now assigned. Several 
of Dr. Lindemann’s notes are worthy of attention. On 
July 19, 1881, the star had a nebulous cometary aspect, with 
sensible diameter. On August 13 in the following year it was 
more stellar, and had no longer the nebulous appearance it 
presented in 1881, though a month later this was again sus- 
pected. On May 13, 1883, we read: ‘‘ V funkelt sehr stark, 
leuchtet momentan auf und verschwindet dazwischen beinahe,” 
though a comparison star DM + 47°, 3162 showed a steady 
light. On July 27 it shone as steadily as the neighbouring stars, 
without any nebulous appearance. On October 8—‘‘sehr 
yerschwommen”’; a week afterwards, this aspect was not 
remarked, though the images of surrounding stars were very 
indifferent. At the end of the same month V was again stellar. 
Variations in the intensity of the colour were also remarked. 
The place of this star for 1885'0, according to meridian 
observation at Pulkowa is in R.A. 20h. 37m. 35°7s. Decl. 
+ 47° 43) 53”. 
OCCULTATION OF ALDEBARAN ON NOVEMBER 22.—The 
Greenwich mean times of disappearance and reappearance of 
this star and the corresponding angles from north point, in the 
occultation on the evening of November 22, may be pretty 
closely determined for any place in this country from the follow- 
ing formula :— 
Time of disap. = 
L + [9°3110] M 
aa reap. L 
+ [9°4779] M 
Angle at disap. = 1041 + [0-358] L — [9°307] M 
oa reap. = 281°6 — [0'412] L + [9°246] M 
In which the latitude of the place is put = 50° + L, and M is 
the longitude in minutes of time counted positive towards the 
east. The quantities within brackets are logarithms. 
The above equations are founded upon the following results 
of direct calculation :— 
Angles from 
Disappearance Reappearance 
N. Point 
: hom. s. hu a. . ° ° 
Greenwich ... 9 48 9 10 57 15 108 278 
Edinburgh OnSaen5 10 56 39 120 264 
Dublin ... 9 46 Io 10 51 o 117 268 
DovuBLe-StTars.— Two important series of measures of 
double-stars have lately appeared in the Astronomische Nach- 
richten : the first in Nos. 2677-78, by Dr. R. Engelmann, of Leip- 
sic, in continuation of a series previously published ; the second by 
M. Perrotin, made at the Observatory of Nice, in Nos. 2684-85. 
According to the Leipsic observations of = 2173, for which Prof. 
Duner found a period of 45 years only, calculation is not yet so 
much in error, as for a first approximation, and so difficult a star, 
might well have been anticipated. Dr. Engelmann’s mean result 
is, for 188388, position, 24°°8 ; distance, 0°23 ; the orbit gives 
34° and o”"2, The Leipsic series contains measures of many of 
Mr. Otto Struve’s and Mr. Burnham’s stars. 
ASTROPHYSICAL NOTES 
STARS WITH SPECTRA OF THE THIRD TyPE.—Prof, Dunér 
has published an important catalogue of stars having banded 
NATURE 
[ Oct. 22, 1885 
spectra. Following Prof. Vogel’s classification he prefers to 
regard the spectra with bands fading away towards the violet 
as a subdivision of the same type as those in which the 
bands fade away towards the red, rather than, with Secchi, to 
make them into a separate class. Dunér’s type III. a, therefore, 
corresponds to Secchi’s third type and his III. 4 to Secchi’s 
fourth type. Prof. Dunér’s purpose in forming this catalogue 
is to supply the means for future observers to detect changes 
in these spectra should any such occur, for, as he points 
out, these stars are probably in a very advanced state of 
development, and we may therefore, perhaps, hope to discover 
some day changes in their spectra which, carefully studied, may 
lead to important results as to the nature of suns. They are the 
more interesting, also, because variable stars of long period 
usually belong to this class. 
With this view Prof. Dunér has carefully examined all the 
known objects of this type which are visible in his latitude, and 
for which the optical means at his command were sufficient, and 
he has catalogued 297 stars of type III. a, that is, with bands 
shading off towards the red, and 55 of type III. 4, with bands 
shading off in the opposite direction. An important section 
follows giving a list of stars which different astronomers have 
regarded as belonging to the third class, but which Dunér cannot 
so classify. Only in a very few instances, however, is there any 
good reason to suspect a change in the spectrum. In the great 
majority Secchi, whose observation ssupply most of these cases of 
discrepancy, had himself at one time or another registered the 
star as being of the second type, z.e. without bands, or else had 
especially remarked on the extreme feebleness of the bands which 
he thoughthe saw. There are, however, three stars observed by 
D’Arrest for which the evidence of change seems stronger, viz. 
24034 LL, D.M. + 60° 1461 and D.M. + 36°2772. Prof. Duner 
has also failed to find Schjellerap No. 249, which is, perhaps, 
along peried variable, and he draws special attention to R 
Andromede, a star the spectrum of which, though of type III. a, 
presents some very marked peculiarities. Great care has been 
taken in the determination of the positions of the bands in the 
different spectra. It is clear, as many spectroscopists have 
already observed, that the bands of type III. 2, occupy the same 
positions in all the spectra of the type, and the same is true for 
the bands of type III. 6. With regard to the former class, the 
sharp dark edges on the more refrangible sides of the bands gene- 
rally coincide with strong metallic lines ; thus one of the most 
prominent bands is terminated by the é-lines of magnesium. The 
nature of the connection between the bands and these metallic 
lines is not ut all clear at present, the symmetrical arrangement of 
the bands seeming to suggest that they are due to some one sub- 
stance rather than to several. The three principal bands of the 
spectra of the other type Prof. Duneér considers to be unmistakably 
those of a carbon compound, and to correspond to the bright 
bands so familiar in the spectra of comets. The determinations 
of the wave-lengths of the bands in spectra of this type are 
necessarily not quite so accurate as those of the bands in spectra 
of type III. 2, but if Prof. Duneér’s measures are accepted, this 
most important correspondence may be considered fully esta- 
blished, But, apart from the value of these measures, Prof. 
Dunér’s catalogue, with the full and clear descriptions he has 
appended to every star, will be of the utmost service to future 
observers of these interesting and beautiful objects. 
THE COMET OF 1866 AND THE METEORS OF NOVEMBER 14. 
—Prof. D. Kirkwood has recently pointed out in a paper read 
before the American Philosophical Society, that there is distinct 
evidence that there are three meteoric swarms travelling in the 
orbit of Tempel’s comet. Of these the principal group is the one 
which produced the great showers of 1833 and 1866, the period 
of which Prof. Adams showed to be about 33°25 years. In 1875 
Prof. Kirkwood identified a second group from the dates of 
meteoric showers given by Humboldt and Quetelet, the period 
of which would be about 33°31 years. The next shower 
from this group will be due about November 13-15, 1887; but the 
display may perhaps commence in November 1886, or even in 
the present year. The third cluster has been less observed ; its 
period is about 33°19 years, and its next return will be from 
1912 to 1915. Prof. Kirkwood suggests that the very great 
diminution in brightness in Tempel’s comet since 1366, the 
comet of that year being now generally regarded as one of its 
apparitions, may possibly be due to the separation of the first 
and largest swarm from the comet having taken place in that year, 
the meteoric shower of that year being nearly contemporaneous 
with the apparition of the comet. 
