302 
NATURE 
[NoveMBER 6, 1913 
two of description in addition to the announcement 
of their publication, in our weekly list of books re- 
ceived. Mr. E. W. Mauader contributes a popular 
account of astrophysics in a volume having the title, 
‘Sir William Huggins and Spectroscopic Astronomy.” 
Dr. W. D. Henderson has written a volume on 
“Biology,” in which he gives in language as free 
from technicalities as possible, a broad account of the 
main facts of the science of life; and Mr. J. Arthur 
Hill writes with dignity and philosophic power upon 
the subject of ‘‘ Spiritualism and Psychical Research.” 
Each volume contains about 96 pp., and is published 
at the price of 6d. net. 
OUR ASTRONOMICAL COLUMN. 
Comer News.—The latest comet discovered, namely 
1913e, (Zinner), has been identified as a return of 
1900 III. (Giacobini), so that it has made two revolu- 
tions since its original discovery, the period being 
6-435 years. Being of about the tenth magnitude and 
its declination a large southerly one, namely, greater 
than 19°, it is not a favourable object for observers 
in high northern latitudes. An ephemeris extending 
to November 14 is given in Astronomische Nachrich- 
ten, No. 4690. 
Herr T. Banachiewicz, as Astronomische Nachrich- 
ten, No. 4689, states, reported a light change in 
comet 1913¢ (Neujmin) on October 6, while on Octo- 
ber 8 the comet could no longer be seen. Dr. Graff 
also looked for the comet in vain. 
Writing to the Astronomische Nachrichten, No. 4690, 
on September 11, Prof. Barnard describes an unusual 
appearance of this comet on September 9. He at first 
thought that a small star was involved in the north 
preceding side of the comet, but further observation 
indicated that the star was travelling with the comet; 
in fact, it was the nucleus. Using the 4o-in. and a 
power of 460 the nucleus was still stellar, but with 700 
it became ill-defined and not so readily taken for a star. 
He concludes in the following words :—‘ The nucleus 
was estimated to be 11:5 magnitude. It was so clear 
cut and distinctly star-like that one would not for a 
moment have suspected any real connection with the 
faint nebulosity apparently attached to it south follow- 
ing. I have not before seen such a striking case 
of a comet being essentially all nucleus.” 
Comet 1913¢ (Westphal) does not gain in bright- 
ness, as was anticipated, in spite of its distance from 
the sun being reduced. The following is a continua- 
tion of the ephemeris printed in Astronomische Nach- 
richten, No. 4687 :— 
12h. M.T. Berlin. 
R.A. (true) Dec. (true) Mag. 
h om. ss ° ‘ 
Nov. 6 20.95 Te ee 24 27:5 8-6 
7 34 46 28 2-0 
8 34 18 28 36:1 
9 33 54 29 99 3-6 
TOA rant 33,32 29 43:4 
Ls aes 33 14 30 16-7 
12 33.0 «=» 30 498 
13). § BOs Manes e 22:6 8-7 
According to Miss S. M. Levy, of Berkeley, Cali- 
fornia, the above ephemeris reads about 23 seconds 
too great in R.A., and about 3-4' too small in declina- 
tion for November 13. During the current week the 
comet passes from Vulpecula into Cygnus, and is in 
a good position for observation. 
NO. 2297, VOL. 92] 
SpPEcTRA OBTAINED BY MEANS OF THE TUBE-ARC.— 
Another important spectroscopic research has just b een 
published by Prof. A. S. King (Contributions from th 
Mount Wilson Solar Observatory, No. 73), who 
been studying the relation of the are and spark li 
by means of a tube-arc. In this paper he presents 
in some detail the leading features of the spectrum 
of this form of arc, and by a comparison with other 
sources he infers the probable character of the radia- 
tion involved. The results discussed and finely illu 
trated are based on fifty plates taken with instrumen 
of different degrees of dispersion. This paper follows 
the one described in this journal in July last (Vol. 
xci., p. 541), and the main results of the inquiry may 
be briefly summarised as follows :—In the study of the 
tube-arc spectrum a region near the centre of the 
tube’s cross-section was found to give the hydrogen 
spectrum and the enhanced lines of metals most” 
strongly, with some variation among different elements 
as to how rapidly their enhanced lines diminish in 
intensity towards the wall. The are lines of two 
groups of elements, represented by iron and calcium, | 
show different degrees of response to the cond 
most favdurable for enhanced lines. The are line 
titanium and vanadium differ from those of the othe 
elements studied, as they show their greatest strength 
close to the wall. On the question of dissymmetry of 
lines produced in the central part of the tube, the dis- 
symmetry is usually towards the red, but some lines | 
show litile or no effect. In the cases of 44481 (M 
and 4267 (C.) the dissymmetry is explained. by 
observation that both these lines are double. Tests’ 
on the ionisation of the vapour and on its conductiv ity 
compared to that of the tube material, together with | 
the spectroscopic phenomena of the tube arc, indicate 
that the effects may largely be due to the impact of 
electrons emitted by the highly heated carbon, the 
resultant effect of these impacts becoming stronger 
near the centre of the tube. Wo! 
KODAIKANAL PROMINENCE OBSERVATIONS AND Dis- | 
cUSSIONS.—Two bulletins, Nos. 31 and 33, of the 
Kodaikanal Observatory, have come to hand dealing — 
with the routine observations of prominences an 
discussion of past data. No. 31, by the director, Mr. 
J. Evershed, is confined to the summary of promin- 
ence observations for the 
first half of the present year. — 
Compared with the previous six months the mean — 
frequency remained practically unaltered, while the — 
mean height slightly increased, and the mean extent — 
somewhat diminished. The eastern limb showed a 
slight preponderance in numbers and areas over the 
western. Only five metallic prominences -were ob- | 
served. Other observations recorded include the dis- — 
placements of the hydrogen lines, prominences pro- — 
jected on the disc as absorption markings, &c. 
Bulletin No. 33 is written by the assistant-director, — 
Mr. T. Royds, and deals with prominence periodici-— 
ties, the investigation being a construction of the — 
periodograms of prominences in the same way as 
Schuster investigated the sun-spot data. Mr. Royds 
confined the Kodaikanal data to the years 1905-1912, 
and determined the mean daily areas by dividing 
the total prominence areas for each month by the 
effective number of days of observation in each month. 
The prominence periodogram finally obtained dis- 
played the presence of three periods of large intensity, 
two nearly homogeneous, of 6} and 73 months, and 
the third, provisionally fixed at 133 months, the 
highest of the band. The mean daily frequencies for 
each month from the year 1881 to 1912, deduced 
from observations at Palermo and. Catania, were 
similarly analysed, as a check, and they indicate 
distinct peaks at the same points as the Kedaikanal 
| curve. The amplitudes of these short periods in 
