274 

NATURE 
[May 6, 1915. 

viz., carbon dioxide, ammonia, and sulphur dioxide. 
The use of these charts is explained in a note by the 
chairman of the committee, Sir J. A. Ewing. The 
chart for carbonic acid uses-Dr. Mollier’s figures, but 
with British units of pressure and with some addi- 
tions based on the recent researches of Prof. Jenkin 
and Mr. Page. For the other two substances the 
experimental data available are much less complete. 
For ammonia, the’ chart must be regarded as no more 
than provisional; values ‘given by Prof.- Goodenough 
and Mr. W. E. Mosher have been adopted. The chart 
for sulphurous acid is also provisional; values given 
by Dr. J. Hybl have been employed. Tables giving 
the properties of these substances are also included. 
ErratuM.—In Nature of April 29, p. 238, col. 1, 
line to from bottom, for ‘solstice’? read “equinox.” 

OUR ASTRONOMICAL COLUMN. 
Comet 1g15a (Metrisu).—The following is a con- 
tinuation of the ephemeris of Mellish’s comet (1915a) 
taken from Astronomische Nachrichten, No. 4796 :— 
R.A. (true) Dec, (true) Mag. 
hom os. é Fi 
INIEWAR) EAase Sahai ain —14 46-2 
SN Scop 57° 6 TOP25-ONS oo. | O25 
Rig rcoae a, UO) OS 18 -17-3 
1s mete Rip 2 Ata Bolen -2e. 3. 6:2 
TA 19 9 32. ....—22 42-1 
The comet: is rapidly- moving southwards, and is 
situated a little to the north of z Sagittarii. 
A third series of elements and an ephemeris of this 
comet are published by Mr. R. T. Crawford, of the 
Berkeley Astronomical Department, in. the Lick Ob- 
servatory Bulletin, No. 270. It is pointed out that 
there seems-to be a similarity. between these elements 
and those of comet 1748 II., and computations are 
being undertaken to test the possibility of the identity. 
Orit Or Jupirer’s) NINTH. SaTELLITE.—A more 
rigorous reduction of the elements of the orbit of the 
ninth satellite of Jupiter is given by Seth B. Nicholson 
in the Lick Observatory Bulletin, No. 271, this being 
a continuation of the investigation previously pub- 
lished in the Bulletin, No.-265 (see this column for 
April 1). The following are -the new elements 
derived :— 
Epoch and Osculation = 1914 August 21:0 G.M.T. 
M=135" 57°2! 
Dimialeh eerste) 
§% =310° 30°6' ¢ 191470 
7 =156° 57°9' 
€ =O'1105 ° 
bu =0°'4518 
P =2'182 years 
log a=9'2192 
As_a result of the alteration in the elements. it is 
stated that the errors in the final elements do not 
exceed 2 per cent. of their values. An. ephemeris for 
the coming opposition is promised at an early date. 
THE SATELLITES OF Uranus.—Two communications 
regarding measures of the satellites of Uranus are 
published in the Lick Observatory Bulletin, No. 269. 
The first, by Prof. R. G. Aitken, were made in 1914 
with the 36-in. refractor using a 350 power eyepiece. 
An interesting opportunity presented itself on July 21 
to estimate their relative brightness. The four satel- 
lites were all south of the planet, Ariel and Umbriel 
almost in line with it, and only a few seconds of arc 
apart. Ariel was seen at the first glance, and was 
NO. 2375, VOL. 93] 



‘conspicuously visible while measuring the other satel- 
lites; Umbriel was seen with much more difficulty, 
and made no impression on the eye except when 
special efforts were made to see it. By direct com- 
parison it was estimated to be from } to ? magnitude- 
fainter than Ariel. The latter appeared to be a mag- 
nitude fainter than Titania; Oberon, from + to 4 
magnitude fainter than Titania.. While these ob- 
servations were being made the sky was very clear, 
the seeing good, and the planet screened by an occult- 
ing bar. Measures of the satellites were made by 
Mr. S._B. Nicholson from photographs taken with 
the Crossley reflector at the Lick Observatory during 
1914. The positions of Uranus and of the satellites 
were measured in rectangular co-ordinates, so that 
the distances of the satellites from either Uranus or 
one of the outer satellites could be obtained. 
THe GREENWICH SECTION OF THE ASTROGRAPHIC 
CaTALoGuE.—The third volume of the Astrographic 
Catalogue 1900-0 deals with the Greenwich Section, 
declination +64° to +90°, and is deduced from photo- 
graphs taken and measured at the Royal Observatory. 
The first portion contains a catalogue of 2212 stars 
within 3° of the north pole in standard rectangular 
co-ordinates. In the original scheme of publication 
this, the third volume, should have included a general 
discussion of results, but the Astronomer. Royal has 
deferred this discussion for a fourth volume. The pre- 
sent catalogue includes: (1) stars used as reference 
stars for the astrographic plates; (2) other stars con- 
tained in the catalogues of the Astronomische Gessell- 
schaft; (3) stars contained in Carrington’s Catalogue 
(1855-0); and (4) stars in the Bonn Durchmusterung 
Zone, 80°. The right ascensions and declinations 
depend throughout on the places of stars observed 
with the transit circle at Greenwich in the years 1897 
to 1905. The. proper motions given in the Greenwich 
Catalogue have been used in forming the constants 
of the plates. In the main catalogue the epoch is 
1900-0. The stars are arranged in zones of declina- 
tion 1° wide, and the photographic magnitudes are 
on the scale of Prof. E. C. Pickering’s north polar 
sequence. 
RECENT PAPERS IN THE ‘‘ ASTRONOMISCHE NACHRICH- 
TEN.’-—The following is a continuation of the chief 
contents. of-some of the earlier numbers of the Astro- 
nomische Nachrichten referred to in this column last 
week :—No. 4785: Trial of the photographic mag- 
nitude-scale of the bright Pleiades stars, by E. Hertz- 
sprung. No. 4784: Observations of Halley’s comet 
1gto I1., made at the Chamberlin Observatory of the 
University of Denver, by Herbert A. Howe. No. 4783: 
Photographic observations of some bright double stars, 
by- E.' Hertzsprung; observations on the brightness 
and; form of: comets, by M. Ebell. No. 4782: The 
special motions of stars with known parallaxes, by R. 
Klumak. | No. 4781: Observations of planets and 
comets made with the 360-mm. refractor of the Copen- 
hagen “Observatory, by C. F. Pechiile and E. 
Strémgren and R. Andersen. No. 4780: Observa- 
tions of the planet Venus, by W. Rabe; definite orbit 
of comet_1906 VII. (Thiele), by E. Waage. No. 4779: 
Observations of the planet Mars, by H. E. Lau; 
observations of the variables U Sagitte and R. S. 
Vulpecule, by M. Maggini. No. 4778: Test for 
variability of 113 Herculis and a Sagitte, by E. 
Hertzsprung ; photographic measures of the magnitude 
difference between the two components of v Draconis, 
by E. Hertzsprung; observations of the variables 
o Herculis, g Herculis, and RZ Cassiopeiz, by M. 
Maggini. No. 4777: Mean elements of sixty minor 
planets, by M. Brendel; ephemeris for Polarissima 
(BD +80° 37’) for 1915, by L. Courvoisier. 


