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THE volume of the Bulletin International of the 
Academy of Sciences of Prague for 1917 appeared in 
1919 under new auspices, but with the handsome 
style and typographic excellence of former issues 
unimpaired. The Academy continues to publish, in 
French or German, much geological, anatomical, 
and physiological work, which will no doubt be re- 
corded in the various Zentralbldtter; but it is a 
pleasure to consult these papers in their original form, 
and to find that their production has so admirably 
survived the test of political distractions. 
THE series of lectures recently given at University 
College, London, by Sir John Russell and members 
of the staff of the Rothamsted Experimental Station 
are to be published by Messrs. Longmans and Co., 
in the “ Rothamsted Monographs of Agricultural 
Science,” under the title of ‘‘ The Micro-organic 
Population of the Soil.” Another book to be issued 
by the same publishers is ‘‘ Lead: Its occurrence in 
Nature, the modes of its extraction, its properties and 
uses, with some accounts of its principal compounds,” 
by Dr. J. A. Smythe, in ‘‘ Monographs on Industrial 
Chemistry.” 
Tue Geologische Vereinigung continues the issue of 
its valuable journal, the Geologische Rundschau, under 
NATURE 

[JUNE 16, 1923 
the care of Profs. Steinmann, Wilckens, and Cloos, 
and the subscription price (10 gold marks for for- 
eigners) compares favourably with that of most of 
our own scientific periodicals. Volume 13, beginning 
in May 1922, contains original articles, such as that 
by Steinmann on the uprising of the Andes, as well 
as the usual critical summaries that embody much 
independent opinion on the part of their authors. 
Scientific libraries will do well, by placing the 
Rundschau on their shelves, to keep in touch with a 
wide range of progressive work, promulgated by 
progressive thinkers. 
PRELIMINARY arrangements for the regular publica- 
tion of the Journal of Scientific Instyruments have now 
been made by the Institute of Physics in co-operation 
with the National Physical Laboratory. The special 
attention of those workers who have new designs for 
instruments is invited to the fact that the Journal 
is to serve as a medium of publication of detailed 
descriptions and critical surveys of the behaviour 
of such instruments. Original papers or laboratory 
and workshop notes dealing with the praetical or 
theoretical aspects of scientific instruments should 
be sent to the Editor, Dr. John S. Anderson, The 
National Physical Laboratory, Teddington, Middlesex. 

Our Astronomical Column. 
PROJECTION OF ALDEBARAN ON THE Moon.—The 
present series of occultations of Aldebaran has once 
more directed attention to its apparent projection 
on the moon’s disc when it disappears at the bright 
limb. The subject is discussed by Mr. R. L. Water- 
field in the British Astronomical Association’s Journal 
for March. He describes some interesting experi- 
ments that he made, using a card with a minute 
pinhole and a lamp behind it as-an artificial star. 
It was found that the brighter the illumination 
of the artificial moon that was made to cover this 
star, the further was the latter projected on the disc 
before disappearance. 
Since diffraction makes every bright point appear 
as a disc in the telescope, this will of itself extend the 
bright limb of the moon beyond its true position, 
and also extend the disc of Aldebaran inwards; a 
considerable fraction, but not the whole, of the 
observed projection is shown to be thus explained. 
The width of the diffraction ring that can actually 
be seen depends on the brightness of the object. 
Thus faint stars do not show the projection. 
To explain the full amount of projection observed, 
it was found necessary to invoke irradiation, which 
is probably physiological and differs for different 
observers ; this is quite in accord with experience 
in the case of Aldebaran. 
FAMILIES oF ASTEROIDS.—Mr. K. Hirayama’s 
researches on the connexion between the orbits of 
many of the asteroids have already been mentioned 
in this column. He returns to the subject in the 
Japanese Journal of Astronomy and Geophysics, vol. i. 
No. 3. He studies the secular perturbations by 
Jupiter and the other planets, and finds quantities 
which he terms “invariable elements,’ which are a 
sort of mean of the actual varying elements. The 
important elements are mean inclination and mean 
eccentricity. He makes diagrams in which these 
quantities are taken as ordinate and abscissa, the 
NO. 2798, VOL. 111] 

third important element, the mean motion, being 
indicated by varying the colour of the dot. He thus 
finds several families of planets that show such 
close agreement in these three points that he has no 
doubt that they had a common origin; he indicates 
5 families, each being called after the earliest dis- 
covered member of it; the names are. Themis, Eos, 
Coronis, Maria, and Flora, and the numbers of asteroids 
belonging to them are 25, 23, 15, 13, and 57. 
There seems to be little doubt that Mr. Hirayama 
has hit on a remarkable relation between the orbits 
of many asteroids, and that there are strong reasons 
for postulating a common origin for each family. 
We thus revert in a sense to the old notion of an 
exploded planet, but a series of disruptions now 
appears more probable than a single one. 
STONYHURST COLLEGE OBSERVATORY, REPORT FOR 
1922.—Sunspots are regularly drawn and measured 
at the College Observatory on every fine day. The 
spot activity showed a decided decline in 1922, there 
being 93 days when the sun was seen to be spotless, as 
against 29 in 1921. On the other hand, the mean 
daily magnetic range, both in declination and 
horizontal force, showed a slight increase. Spectro- 
scopic work was also done, both on the sun and on 
stars, a special study being made of y Cassiopeie. 
Papers have been contributed to the Observatory, to 
Monthly Notices of the R.A.S. and elsewhere, on the 
connexion of magnetic disturbances with sunspots, 
on the prominences, and on the proper motions of 
stars in the Perseus clusters. Seismological records 
were also kept. The disturbance in the Chilian 
earthquake of November 11, 1922, was so great that 
the boom adhered to the stop, causing a loss of part 
of the record. The report also contains full details 
of the meteorological observations. Father Cortie 
notes that it is intended to utilise the large stock 
of stellar spectra at the Observatory for the deduction 
of spectroscopic parallaxes. 
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