NOVEMBER 13, 1913] 
NATURE 
32 
observations was published in the Bulletin de 
V’Académie Impériale des Sciences de St. Petersbourg 
(April 24, 1913). In the current number of The Ob- 
servatory (November) Mr. F. J. M. Stratton gives an 
account of the work of Belopolsky on this star, and 
Mr. F. E. Baxandall contributes a communication on 
the chemical origin of certain of the spectrum lines. 
Some of the conspicuous lines in the spectrum of this 
star which underwent periodic changes were those at 
4A4130-:04 and 4205-20, lines of unknown origin. Mr. 
Baxandall has now identified these lines as two very 
strong lines of Europium, and the evidence is the 
more convincing as the other lines of Europium in 
the region of the spectrum photographed by Belopol- 
sky are found also to be represented. Two other 
strong lines of Europium are just outside the photo- 
graphed region of the star, and, as Mr. Baxandall 
points out, it would be of very great interest to know 
whether these lines are represented also. The pre- 
sence of Europium lines in stellar spectra has pre- 
viously been suggested by Mr. Lunt in the case of 
Arcturus, and Dr. Dyson and Mr. Jewell have identi- 
fied them also with weak lines in the spectrum of 
the chromosphere. 
RaptaL VELOCITIES WITH THE OBJECTIVE PrisM.— 
The problem of obtaining radial velocities by means 
of the objective prism is one that needs urgent solu- 
tion, and few practical workers have as yet taken the 
subject up. Dr. Frank Schlesinger sums up in a 
very interesting way the state of the problem to-day 
(Proc. Amer. Phil. Soc., vol. lii., No. 209, April, 1913), 
and stellar spectroscopists will no doubt be glad to 
have their attention directed to this paper. He re- 
views three methods of procedure, all of which, he 
says, warrant a trial, but he thinks that the process 
involving an absorptive medium to produce one or 
more narrow and sharp absorption bands, such as 
neodymium chloride, would probably lead to imme- 
diate results provided a moderate degree of precision 
is only wanted. Dr. Schlesinger’s remarks apply 
chiefly to the spectra of stars fainter than the fifth 
magnitude, for the brighter stars are well dealt with 
by means of slit spectroscopes, instruments which only 
utilise a very small percentage of the light which falls 
on the slit plate. 
Sotar Activity aND CycLonges.—In addition to the 
detailed observations of the meteorological elements 
for the year 1912, No. 2 of the Annals of the Observa- 
tory of Montserrat, Cuba, contains a study of the 
synchronism between solar activity and the hurricanes 
of the Antilles, by the director, Father Simén Sara- 
sola, S.J. It appears that each of the last four sun- 
spot minima was followed by minima of cyclonic 
activity. Further, it is stated that maxima of cvclonic 
and solar activities do not coincide, although cyclones 
are frequent and violent about the time of a maximum 
of sun-spots. The dates given show a minimum of 
cyclonic activity in the year 1884, thus almost coin- 
ciding with a spot maximum. 
MICROSCOPE STANDS AND OBJECTIVES. 
WE have received from Messrs. Swift and Son 
their catalogue of microscopes and accessories. 
The microscope stands listed are of varying degrees of 
complexity suited to the requirements and pockets of 
all classes of microscopists. The higher priced stands 
all have centring substage condensers, and are fitted 
with the ‘‘improved climax” fine adjustment. This 
is constructed with an accurately cut micrometer 
screw with graduated drum fixed horizontally parallel 
to the coarse adjustment, and with milled heads on 
either side of the pillar. The adjustment automatic- 
ally ceases to act should the objective touch the cover- 
NO. 2298, VOL. 92] 
glass. The ‘ Premier,” first constructed to the speci- 
fication of Mr. J. E. Barnard, for the bacteriological 
department of King’s College, London, is one of the 
most perfect stands we have seen (see figure). It is 
| swung on an arc on the “ Wales”’ principle; the body- 
tube is of wide diameter, adapted for use with wide- 
angled photographic lenses, and is provided with two 
graduated draw-tubes, one of which is actuated by 
a rack and pinion. The substage has centring screws, 
and the iris diaphragm can be racked eccentrically 
and rotated, so as to allow of the use of light of any 
azimuth, and can be swung out of the optic axis 
independently of the condenser. 
A full series of apochromatic objectives, of which 
Messrs. Swift are the sole British makers, is also 
listed, and we have had the opportunity of examining 
two of the 1/12 in. oil immersions with numerical 
aperture of 1-4. Tested with a Zeiss apertometer, one 
of these lenses was found to come up to 1-4, the other 
was slightly less—1-37. With both lenses the image 
was free from colour, and the definition excellent, 
even with the higher-power compensating oculars, and 
both lenses compare very favourably in all respects 
with similar lenses of other makers at double the price. 
We think it would be an advantage if the tube-length 
Were engraved on the mounts of these lenses. 
CHEMISTRY AT. THE BRITISH 
ASSOCIATION. 
lige chemical section was well supported through- 
out the meeting both by chemists and by the 
general public. The programme was a varied one, 
appealing both to the specialist and to the public 
generally. In particular, the discussion on fuel was 
of extreme importance, and it was evident that though 
