52 
scale. Over this range the specific heats of fluorspar 
and iron pyrites crystals vary as the third power of 
the absolute temperature in agreement with the theory 
put forward by Debye in the first instance for 
monatomic substances, 
“THe Coal Resources of the World,” to which 
allusion was made in NatupeE of September 4, is being 
brought out in this country by the American Book 
Supply Co., Ltd., 149 Strand. 
OUR ASTRONOMICAL COLUMN. 
A_New Comer.—A telegram from the Centralstelle 
at Kiel, dated September 3, announced the discovery 
of a comet of magnitude 10-0 by Dr. Metcalf, of Win- 
chester, Massachusetts, on September 1, at 8h. 42-0m. 
M.T. Winchester. Its position was given as RA 
6h. 50m., and declination 57° o’ N., and was stated to 
have a slow motion to the north. It was suggested 
that it possibly might be Westphal’s comet. A second 
telegram, dated September 4, stated that Prof. 
Antoniazzi had seen the same object on September 3 
at.1sh. 394m. M.T. Padua. The position he gave 
was RA 6h. 48m. 12s., and declination 570 Shan aINe 
the daily motion in RA being —1m. 16s., and in 
declination +34’. According to a writer in The Times 
(September 6), Prof. Antoniazzi’s observation indicates 
that the comet cannot be that of Westphal, as the 
daily motion is diminishing instead of increasing. 
The new comet is in the constellation of the Lynx, 
and therefore to be observed any time during the 
night, but best visible after midnight. 
The following elements and ephemeris of comet 6 
(Metcalf) have been communicated from Kiel, based 
on the observations of September 2, 3, and 4 :— 
T=1913 July 20.1129 Berlin. 
w= 51° 31°47’): 
2 =136° 035 bons, 
Z =142° 49°23’ 
log g =0'20954 
12h. M.T. Berlin. 
R.A. Dec, 
hom. os ° , 
Sept. 11 6 32 54 +62 21°6 
13 27 1 63 44°7 
15 6 19 53 65 105 
The magnitude is given as Io-5 on September 5 and 
Io-3 on September 15. 
ANOTHER Cometr.—Another telegram from Kiel, 
dated September 7, states that Dr. K. Graff discovered 
on September 6, at 15h, gum. M.T. Bergedorf, a 
comet of the 11th magnitude. Its position is given as 
R.A. 23h. 48m. 1-8s., and declination 0° 27! Aal Ss 
It is thus situated in the constellation of Pisces, and 
should be best seen about midnight. 
Tue Prorecrion oF SILVERED Mirrors FROM Tar- 
NISHING.—Everyone who uses mirrors for astronomical] 
purposes would welcome a satisfactory method of 
coating them with some material for preventing 
tarnishing. M. Perot some years ago published an 
account of a process he employed successfully for 
treating mirrors at the Meudon Observatory. It con- 
sisted of a thin coating of collodion being applied to 
the surface of the mirror, the film being obtained by 
pouring over the mirror a solution of collodion in amyl 
acetate. The mirrors used at the Helwan Observa- 
tory are subject to becoming spotted a few weeks 
after silvering, and attempts have been made to pro- 
tect them. Mr. S. H. Trimen, of the Survey Depart- 
ment Laboratories, made the various trials (Khedivial 
Observatory, Helwan, Bulletin No. ro), but after 
NO. 2289, VOL. 92] 
NATURE 
‘number of this journal (June 17, 
[SEPTEMBER 11, 1913 
repeated attempts with solutions of varying  per- 
centages he had at length to abandon the process, 
Blurred images of the stars and curious flares on the 
photographs of the bright stars were always the result 
of the application of the fil. It is suggested that 
the problem may possibly be solved by using a solution, 
possessing a lower viscosity, and it is to be hoped 
that such an attempt will be made. 
RESEARCHES ON THE SuN.—The last two numbers of 
the Astrophysical Journal (June and July) have con- . 
tained several important researches relating to solar 
physics. Prof. George E. Hale, in the July number, 
publishes his most valuable paper on the * Prelimi 
Results of an Attempt to Detect the General Magnetic 
Field of the Sun,’ a summary of which, based on an 
advanced proof, having been given in a previous 
p- 505). In con- 
nection with this research, Mr. Frederick H. Seares 
gives in the same number a paper entitled, “‘ The 
Displacement-curve of the Sun’s General Magnetic 
Field.” The spectrum lines observed with the 75-ft. 
Spectrographs and the polarising apparatus of the 
150-ft. tower telescope showed displacements that 
apparently could not be attributed to any other cause 
than a general magnetic field of the sun, and the 
object of his research was to provide a more rigorous 
control of the results and their interpretation. Thus 
in the paper he compares the observed displacements 
with the theoretical displacement-curve derived on the 
assumption that the sun is a magnetised sphere, and 
further he provides formula for determining the posi- 
tion of the magnetic axis relative to the axis of rotation. 
In the June number Mr. Charles E. St. John deals 
with the remarkable discovery by Mr. Evershed of 
the displacement of the Fraunhofer lines in the 
penumbrz of sunspots. The paper is entitled, ‘The 
Distribution of Velocities in the Solar Vortex,” and 
the observations recorded in this research are in entire 
accord with Mr. Evershed’s hypothesis that the dis- 
placements considered are due to a movement of the 
solar vapours tangential to the solar surface and 
radial to the axis of the spot vortex. Previous refer- 
ence has already been made of Prof. Slocum’s second 
paper on the circulation in the solar atmosphere as 
indicated by prominences. 
THE INSTITUTE OF METALS. 
THE autumn meeting of the Institute of Metals 
took place at Ghent on August 28 and 29 last. 
This was the first occasion on which this institute 
has held a meeting abroad, and the gathering may be 
described as a complete success. The attendance of 
members (about seventy-five) was particularly satis- 
factory on account of the representative character of 
those present, the foreign members of the institute, 
including members from Russia, Germany, Belgium, 
and America, being particularly well represented. The 
mornings of August 28 and 29 were devoted to the 
discussion of a long and interesting list of papers, 
while the afternoons were utilised for visits to works, 
the inspection of the exhibition, and the antiquities 
of the city. The social functions included a reception 
by the Burgomestre of Ghent in the ancient and 
beautiful Hotel de Ville. 
The foremost place in the work of the meeting was 
taken by the reading and discussion of the second 
report to the Corrosion Committee, presented by Dr. 
G. Bengough and R. M. Jones. This report deals 
with the examination of a considerable number of 
examples of corroded tubes from service, of the inves- 
tigation of the mechanism of corrosion in sea-water, 
both at the ordinary temperature and at higher tem- 
peratures by means of small laboratory experiments, 
