240 
NATURE: 
[OcToBER 23, 1913 
OUR ASTRONOMICAL COLUMN. 
Comet News.—Astronomische Nachrichten (No. 4686) 
gives improved elements for comet 1913b (Metcalf), 
and also an ephemeris, including the current week, 
from which the following positions are taken :— 
12h. M.T. Berlin. 
R.A. (true) Dec. (true) Mag. 
bs mic, “s: a i 
Oct. 23 ZOST 54). 15. 78 | 
24 BO) GEV os. 3 18:9 
25 49 57 Ir 36:2 gil 
26 pede Ooi 
27 48 26 8 28-6 
28 47 50 rn) ; 
29 ai 2) Ses O77 
30 20 46 53 +4 258 
The comet is rapidly reducing its northern declination, 
and as its magnitude is also decreasing it will become | 
an object only for larger apertures. 
Westphal’s comet is becoming an interesting object, 
and will for some time be in a good observing position. 
It is moving into the constellation of Vulpecula, and 
during the first week of November will pass into 
Cygnus and become involved in the Milky Way. A 
photograph taken on September 28 showed a broad 
tail 3-5° long, a round nucleus of 20 min. in diameter, 
and a distinct nucleus. It has been glimpsed with the 
naked eye, and is an easy object for binoculars. The 
following is an approximate ephemeris :— 
Bae Dec. 
» m ° ‘ 
Oct. 24 20 48 +19 46 
28 43 22 29 
Nov. 1 39 24 50 
5 20 36 +27 16 
It is worthy of note to mention that both Westphal’s 
and Metcalf’s comets are in about the same region of 
the sky, being less than two degrees apart on October 
The following are three positions for comet 1913¢ 
(Neujmin), now a faint object, published in Astro- 
nomische Nachrichten (No. 4685) :— 
R.A. (true) Dec. (true) 
h m. s. a F 
Oct. 22 2394) <0 - +13 55°7 
26. 35 29 14 33°3 
30, + 37 29 15 74 
The same journal (No. 4686) publishes the informa- 
tion received by Banachiewicz to the effect that the 
brightness of Neujmin’s comet appears to be fluctuat- 
ing. Its magnitude is fainter than 11. 
Orsits oF E1cuty-sEVEN Ec.ipsinc Binaries.—Dr. 
Harlow Shapley contributes to The Astrophysical 
Journal for September (vol. xxxviii., No. 2)a summary 
of an important though laborious piece of work on 
the orbits of eighty-seven eclipsing binaries. In the 
present publication he restricts himself to a few of 
the general results, leaving the complete statistical 
discussion for a future Princetown University Observa- 
tory publication. Some of the conclusions here briefly 
summarised show that the better the observations of 
an eclipsing binary are, the more satisfactory is the 
theoretical representation of the light variations. Fur- 
ther irregularities in the shape of the light-curves dis- 
appear with increased photometric accuracy. The 
existence of darkening towards the limb of the stellar 
disc is clearly indicated, and actually demonstrated in 
a few cases. There is a positive indication that the 
fainter star is self-luminous, and no case arises where 
it is necessary .to assume one component completely 
dark. In discussing the distribution of densities rela- 
tive to spectra the first-type stars (spectra B and A) | 
NO. 2295, VOL. 92| 
show a marked preference for an intermediate density. 
The second-type stars fall into two groups, one pre- 
ceding and the other following” in order of density 
the first-type stars. Dr. Shapley points out that these 
two groups are obviously identical with the two 
classes of second-type stars of very greatly different 
luminosity discussed by Hertzsprung and Russell, and 
the facts collected afford direct support of Russell’s 
theory that the differences in brightness of the two 
| groups are to be ascribed in the main to great differ- 
ences in the mean density. 
VARIATIONS IN THE EartH’s MaGnetic Firrp.—In a 
short article in Science (August 29, 1913) Prof. Francis 
E. Nipher states that a series of open-air observations 
has fully verified the conclusions he has published — 
regarding local magnetic storms. It appears that 
clouds prevent the solar ionisation of the air in their 
shadows, just as does the earth. When the molecules 
of air are ionised they become little magnets, and 
arranging themselves along the lines of force add 
their effect to that of the earth’s magnetic field. In 
the absence of the solar radiation, wind or falling 
rain destroys this arrangement. It is hence suggested 
that local, daily, and annual variations are due to 
local variation in the weather. In a previous article 
in Science (May 30) Prof. Nipher describes a model 
with which a somewhat similar magnetic storm can 
be produced experimentally. In the model iron filings 
take the place of the ionised molecules of air. 
Tue Licht Curve or o Ceri.—In the Memorie 
della Societa degli Spettroscopisti Italiani, September, 
1913, Sig. G. B. Lacchini publishes the results of his 
observations of this variable made during the period 
July 12, 1912-March 11, 1913. He used a telescope of 
6 cm. aperture, 80 cm. focal length, with powers 
of 20 and 4o, the comparison stars employed 
being those of the variable star section of the B.A.A. 
The epoch of minimum found was December 10, 1912, 
a result differing by only one day from that found 
by Dr. E. Guerrieri (December 9, 1912). The star 
lost one magnitude per twenty-seven days, and gained 
one magnitude per eleven days, according to Sig. 
Lacchini, which figures compare with 296 days and 
nine days respectively as determined by Dr. Guerrieri. 
The actual faintest magnitude recorded was 9:09 on 
December 3, 1912. = 
THE FRAUENFELD MEETING OF THE 
SWISS SOCIETY FOR THE ADVANCEMENT 
OF SCIENCE. 
ae. ninety-sixth annual meeting of the Société 
Helvétique des Sciences Naturelles was held, as 
already announced, at Frauenfeld in September. The 
set discourses were largely attended, and were listened 
to with considerable interest. Prof. Grubemann, in 
his lecture on the most recent methods employed in 
petrography, referred especially to the evolution of 
rocks, and the bearing of metallography and_ the 
chemistry of colloids on his subject. Prof. Maillefer 
gave an account of his researches on the geotropism 
of plants, partly from an experimental and partly 
from a mathematical point of view. He claimed to 
have proved that gravity has an effect on the curva- 
ture of a plant which requires time to take effect, 
and may be expressed by saying that the curvature 
possesses a velocity proportional to the sine of the 
angle made by the plant with the vertical and an 
acceleration proportional to the time of exposure. 
The effect is, he said, felt by the plant from the 
outset, though the time measurements seem to depend 
on the instruments used in the observations. His 
results were in a subsequent communication partly 
