NOVEMBER 29, 1906 | 
WEA TORE 
Gel 1 
of a different character; the latter view appears necessary 
to explain the variation in chemical activity. 
In the formula given in last week’s Nature (p. 85) for 
converting Fahrenheit to centigrade degrees, the minus 
signs should have been plus; thus 
C=(E+4. oot+h -. rz) (F -32). 
Though the formula was incorrectly stated, the example 
given of its use showed plainly that a plus sign was 
intended. 
OUR ASTRONOMICAL COLUMN. 
ASTRONOMICAL OCCURRENCES IN DECEMBER :— 
Dec. 3. 3h. Jupiter in conjunction with Moon. Jupiter 
ee Gish NG 
5, Joh. 36m. to rrh. rom. Moon occults ¢ Geminorum 
(variable). 
5. tth. 15m. Minimum of Algol (8 Persei). 
8. Sh. 4m. Minimum of Algol (8 Persei). 
to-12. Epoch of Geminid meteoric shower (Radiant 
108°+ 33°). 
9. 6h. Venus in conjunction with B’ Scorpil. 
13. 2h. Mercury and Venus in conjunction. Mercury 
o° 49’ N. 
s, 18h. Im. to 19h. 28m. Transit of Jupiter's Sat. IV. 
(Callisto). 
s, 19h. Venus in conjunction with Moon. Venus 
2° 40’ S. 
15. Venus. Illuminated portion of disc =0'075; of 
Mars =0'938. 
19, 4h. 40m. to 5h. 39m. Moon occults y Capricorni 
(mag. 3°8). 
»» 8h. 32m. to 8h. 54m. Moon occults 6 Capricorni 
(mag. 370). 
20. 13h. Saturn in conjunction with Moon. Saturn 
Mes; ON 
24. 3h. 26m. to 6h. 26m. Transit of Jupiter's Sat. IIT. 
(Ganymede). 
25. Saturn. Major axis of outer ring =38''59 ; minor 
axIS) 3,79, 
», oh. 59m. to 12h. 
(mag. 4°4). 
12m. Moon occults u Ceti 
28. 3h. Jupiter in opposition to the Sun. 
»» 9h. 46m. Minimum of Algol (8 Persei). 
30. 8h. 6m. to gh. 37m. Transit of Jupiter’s Sat. IV. 
(Callisto). 
31. 6h. 35m. 
+, 6h. 41m. to oh. 41m. 
(Ganymede). 
Minimum of Algol (8 Persei). 
Transit of Jupiter’s Sat. ITT. 
Comets 1906g (THIELE) AND 1906h (MercaLr).—Further 
observations of comets 1g06g and i1906h are recorded in 
No. 4134 of the Astronomische Nachrichten. Prof. Hart- 
wig, observing at Bamberg on November 11, found that 
1906g was of circular form with a diameter of 2’, having 
a central condensation 1’ in diameter and of the tenth 
magnitude. On November 14 the condensation was very 
hazy and difficult to measure, whilst the total magnitude 
was about 9-0. Several sets of elements and ephemerides 
are published in the same journal, and the following is 
an extract from the ephemeris computed by Dr. E. 
Strémgren :— : 
, Ephemeris 12h. M.T. Berlin. 
1906 a (true) 6 (true) Brightness 
5 h. m. s 
INTO (0). ARCO Mae (It) © ats)! 55 eRe acto) an) ial Beanies 
Dec, (2 wey oe ap Pema A OA cot sas LES 
Jet Son Royle. ASG OL wecta se: 
Ey) On we ty DSA nemeE ONDA’ crxcy (ene Ls 2 
Brightness at time of discovery=1-0 (=mag. 8-5). 
_ The comet is now circumpolar, and apparently travelling 
in a line roughly parallel to, and south of, that joining 
w and x Urse Majoris. 
Comet 1906h is so faint that it may only be observed 
with large telescopes. 
WON OeS. VOL: 75) 
PHOTOGRAPHIC OBSERVATIONS OF GIACOBINI’S 1905 
Comet.—Some excellent photographs of comet 1905c, taken 
with the ro-inch Brashear doublet of the Yerkes Observ- 
atory by Prof. Barnard, are reproduced in No. 4, vol. 
xxiv., of the Astrophysical Journal. That secured on 
December 29, 1905, shows a great deal of structure in a 
tail 43° long. Joined to the comet's head by a narrow 
neck, this tail first broadens out and then narrows again, 
its well-defined edges thus presenting a peculiar convex 
appearance. The photograph taken on January 7, 1906, 
shows an even greater amount of structure, a large number 
of thread-like strands diverging from a position about 1° 
from the head. Although the tail of this comet was sub- 
ject to great physical changes, Prof. Barnard considers 
that all the phenomena were due entirely to the solar 
action, there being no evidence of any outside distorting 
influence such as was suspected in the case of Brooks’s 
comet (1903 IV.). 
Sun-spots AND MaGnetisM.—A retrospect of the stages 
whereby our present knowledge of the relation between 
sun-spots and terrestrial magnetism has been advanced at 
Greenwich is published in the Observatory (No. 376) by 
Mr. William Ellis. For a long period Mr. Ellis had 
charge of the magnetic observations at Greenwich, and 
he describes steps of advance in which he took an actual 
part. These observations were commenced at Greenwich, 
and in several of our colonies, in 1840, and in September 
of the next year there occurred a considerable magnetic 
storm which was clearly shown to have commenced simul- 
taneously in widely separated parts of the Empire, thereby 
suggesting an external independent cause. By the year 
1852 General Sabine, from a discussion of the collected 
results, was able to suggest that this common cause was 
probably intimately connected with solar phenomena. Mr. 
Ellis proceeds to discuss the observations of both solar and 
magnetic phenomena, giving a number of direct references 
which should prove both interesting and useful to other 
observers. 
Tue Soar Ecuirse or Next January.—The Tashkent 
Observatory has issued a map of Turkestan showing the 
path of the moon’s shadow during the total solar eclipse 
which will take place on January 13, 1907. In the circular 
accompanying the map a series of meteorological observ- 
ations is given, and these show that the prospects of a 
clear sky during the eclipse are not particularly favour- 
able. So far as is yet known, three expeditions, one each 
from the Pulkowa and Hamburg Observatories, and one 
from the Bureau des Longitudes, are going to Samarkand 
(Astronomische Nachrichten, No. 4133). 
NAKED-EYE OBSERVATIONS OF VENUS.—In the November 
number of the Bulletin de la Société astronomique de 
France M. A. Benoit discusses numerous recorded instances 
of the crescent form of Venus having been seen by the 
unaided eye. To determine the question of the probability 
of such an observation being possible, a number of observ- 
ations was especially made at the Juvisy Observatory 
during the period March-June, 1905. Although on one 
occasion the observers thought they certainly saw the 
crescent, subsequent examination with field glasses showed 
them to have been mistaken, and from the complete dis- 
cussion M. Benoit concludes that this naked-eye observ- 
ation is impossible. 
Tue INTERNATIONAL CHART AND CataLocuE.—As the com- 
pletion of the international scheme for charting the heavens 
is now within sight, a correlated history of its inception 
and prosecution should prove of general interest. Such an 
account is given, in German, in No. 48, vol. v. (new 
series), November 25, 1906, of the Naturwissenschaft- 
liche Wochenschrift by Dr. H. Ludendorff, and is illus- 
trated by engravings of the instruments and a reproduction 
from a portion of one of the Potsdam plates. 
Tue PERSEIDS, 1906.—In No. 10, vol. xxxv., of the 
Memorie della Societé degli Spettroscopisti, Prof. Zam- 
marchi records the results of the meteor observations made 
on the nights of August 10-14 at the Vescovile di Brescia 
Observatory. In all, 231 Perseids were observed, and for 
the majority of these the paths, brightness, colour, &c., 
are recorded. Many of the meteors left persistent trails, 
and two of them apparently followed zigzag paths. 
