JUNE 10, 1915] 
NATURE 
405 


OUR ASTRONOMICAL COLUMN. 
PARALLAXES OF Four  VisuaL  BINARIES.—The 
parallaxes of four visual binaries have been determined 
by Mr. F. Slocum from photographs taken with the 
4o-in. refractor of the Yerkes Observatory, the values 
of which are given in the Astrophysical Journal (vol. 
xli., No. 3). The following is an abridged summary 
of the results :— 
Sir ese oeh eee  Pebetle 
42 Come Sian 049 2. 01058 +o0'008 
n Coron Gree. 0723" ce Ol07,3 OO14 
70 Ophiuchi.. K TE3 +0'212 0007 
85 Pegasi ... G 1°30 +o°084 tororo 
The author then gives two further tables showing 
the absolute parallax, cross velocity, motion in space, 
mass, and luminosity of each system, together with 
the elements of the orbits, the radial velocities, and the 
magnitudes. The following abridged table indicates 
some of the above results :— 
Absolute parallax Period Mass of 
of binaries in years system 
42 Come + 0-062 25:3 1-97 
7 Corone 0-076 41-6 0-94 
70 Ophiuchi 0-216 87-9 1-22 
85 Pegasi +0-088 25:4 1-21 
ABNORMAL VARIABILITY OF Mira Ceti.—The variable 
o Ceti, or Mira, is perhaps the most interesting of all 
known variables, and its large range of magnitude, 
varying from a bright naked-eye star to invisibility, 
renders it an object of fascinating study. It is, how- 
ever, a variable variable, for not only does its period of 
waxing and waning oscillate from about 320 to 370 
days, but the brightnesses at maxima or minima do 
not always reach the same values. Sometimes the 
magnitudes reached at maxima are estimated to be 
from 1°2 to 3°9, and the minima magnitudes vary from 
80 to 95. It is quite possible that these minor changes 
are themselves periodic. A note on the recent be- 
haviour of this star is printed in the Memorie della 
Soc. degli Spett. Italiani (vol. iv., ser. 2, March), and 
in it Sig. A. Bemporad refers to the recent abnormal 
maximum. He points out that at the last maximum, 
which occurred in the present year, the variable only 
reached magnitude 42, while the previous maxima in 
Ig10, 1911, and 1914 were 3°3, 3°5, and 3'6 respectively. 
Unfortunately, no data are given for the years 1912 
and 1913, for it could then be seen whether there had 
been a gradual diminution of the brightness at maxi- 
mum during those years. The values for the ampli- 
tudes (in magnitude) of the light waves, estimated 
from a minimum to a following maximum, are given 
by him as follows :— 
IQtO-11 IQtI-12 1913-14 1914-15 
m. m. m. m. 
6:2 6-2 6:0 5:2 
and these values show a flattening out of the curve, 
especially during the last period. The.intervals in days 
occupied from a minimum to the following maximum, 
for the same years as given above, were 118, 129, 122, 
104, and these values again show the abnormality of 
the recent maximum. 
Another communication on recent observations of 
this variable appears in Astronomische Nachrichten, 
N. 4801. This is contributed by Prof. A. A. Nijland, 
who gives a bright curve extending from July, 1914, 
to March of the present year. According to him, the 
minimum occurred on October 10 of last year and the 
maximum on January 29 of the present year, its 
magnitude not exceeding 4-0 with the naked eye on 
the latter occasion. 
NO. 2380, VOL. 95| 

REPORT OF THE BomBAy AND ALIBAG OBSERVATORIES. 
| —The director of the Bombay and Alibag Observa- 
tories, Mr. N. A. F. Moos, presents his report on the 
| conditions and proceedings of these observatories for 

the year ending December, 1914. As the work is 
chiefly routine, namely, time, meteorological, and 
magnetic observations, which vary little from year to 
year, the report is very similar to those of former 
years. It shows that the observatory has been free 
from plague or any other infection during the past 
year, although a severe epidemic raged in the town 
during the winter months up to the middle of May; 
that the time-balls were dropped successfully on almost 
every occasion; that the magnetic instruments are in 
good working order; that the Milne seismograph 
recorded forty-seven earthquakes during the year, one 
of which was a great disturbance (May 26), besides 
several small local and other movements, etc. A long 
list is given of the routine operations, and it is stated 
that the major portion of the volume of magnetic 
disturbances, charts, data, and discussion for the years 
1906-14, which brings up to date the data, etc., pub- 
lished in the magnetic volume 1846-1905, is in the 
press, and expected to be completed shortly. The 
magnetic work in connection with the programme of 
the Australian Antarctic Expedition was completed 
during the year. 
THE ANNUAL OF THE NATIONAL OBSERVATORY OF RIO 
DE JANEIRO.—The issue of the annual of the National 
Observatory of Rio de Janeiro is the thirty-first of the 
series, and, like its predecessors, contains a large 
amount of useful tables and data. The volume is 
divided into four parts, the first dealing with the 
calendar and astronomical data for the present year, 
the second composed of tables, etc., for the reduction 
of astronomical observations, the third giving a 
Synopsis of the metric system, different units, and 
physical constants, and the fourth and last part con- 
cerning geo-physics and clirnatology, tables of the tides 
for numerous places forming an important portion of 
this section. 
AGRICULTURAL RESEARCH AT THE 
ROTHAMSTED EXPERIMENTAL STATION.1 
HE Rothamsted Experimental Station was for 
many years entirely supported by the generosity 
of its founder, the late Sir John Lawes, but latterly, 
as one of the institutes for agricultural research to 
which grants are made from the Development Fund, 
has been able considerably to extend the scope of its 
operations. Thanks to this assistance and to numerous 
private benefactions, the station has been able to 
enter into occupation of the Home Farm at Rotham- 
sted, giving it scope for the desired increase in its 
field-work, and of a range of new laboratories, now 
nearing completion, that will compare favourably with 
those of any other institution of a similar nature. 
The day is past when a chemist alone could supply 
all the science an agricultural experiment station 
could be supposed to need; chemistry itself has become 
differentiated, and some of the agricultural problems 
demand the specialisation of an organic as others of a 
physical chemist over and above the purely analytical 
work that still constitutes so much of the routine 
of such a station. Biological questions are also 
involved, so that we see on the enlarged staff of the 
Rothamsted Station bacteriologists, botanists, and a 
protozoologist. 
Dr. Russell, in recording the pulling down of the 
old laboratory wherein for sixty years so much of 
the pioneer work of the science has been accomplished, 
. Lawes 
Agricultural Trust. Rothamsted Experimental Station, 
Harpenden. 
Annual Report for 1914. (Harpenden: D. J. Jeffery, 191s.) 
