NABORE 
[ DECEMBER 20, 1906 
In a communication to the Royal Academy of Belgium 
(Bulletin No. 7, p. 452) Prof. Walthére Spring shows that 
the material obtained by decomposing a solution of 
hydrogen sulphide with sulphur dioxide, and formerly de- 
scribed as 8 sulphur by Debus, who considered it to be 
an allotropic form of the element, is in reality a hydrate 
having the composition S,,H,O. The hydrate has at the 
ordinary temperature a vapour pressure much smaller than 
that characterising most hydrates. When, however, it is 
exposed for a long period in a vacuum it gradually loses 
water, a form of sulphur being produced which differs 
from the known forms in its regenerating the hydrate when 
left in contact with water. It is interesting to note that 
the composition of the hydrate corresponds with the mole- 
cular weight S,, which has been found by physical methods 
to characterise sulphur in solution. 
Mr. W. B. Curve has published a second edition of 
‘Graphs: or the Graphical Representation of Algebraic 
Functions,’’ by Messrs. C. H. French and G. Osborn. The 
book has been expanded, chapters having been added on 
harder graphs and on the slope of a graph. 
A sEconp popular edition of Mr. Oliver Pike’s “In 
Bird-land with Field-glass and Camera’’ has been pub- 
lished by Mr. T. Fisher Unwin. The first edition of this 
attractive volume was reviewed in our issue of August 30, 
1900 (vol. Ixii., p. 417), and it is unnecessary to add any- 
thing to the favourable opinion then expressed. 
WE have received tickets for Mr. Otho Stuart’s revival 
of A Midsummer Night’s Dream at the Adelphi Theatre. 
We are glad to know that the management is presenting 
this delightful comedy, which, unlike many of the modern 
plays, is not based upon impurity or inanity, but provides 
all who see it, whether children or adults, with innocent 
enjoyment and real delight. An arrangement has been made 
by which schools and parties of students may receive special 
terms of admittance, for particulars of which application 
should be sent to Mr. C. F. Leyel at the Adelphi Theatre. 
A second edition of Mr. J. H. Stansbie’s ‘‘ Introduction 
to Metallurgical Chemistry for Technical Students’ has 
been published by Mr. Edward Arnold. The book assumes 
that those who use it are practically interested in the 
common metals, but have only the knowledge of their 
properties gained by every-day observation in the work- 
shop or foundry. The scientific study of the subject con- 
sequently starts at the beginning. The text is practical in 
character, and will be useful to the technical students for 
whom it is intended. 
OUR ASTRONOMICAL COLUMN. 
Systematic STELLAR Motions.—In a paper submitted to 
the Royal Astronomical Society Mr. A. S. Eddington dis- 
cusses the proper motions of the stars contained in the 
Greenwich-Groombridge catalogue from the point of view 
that they are not haphazard, but may be considered as 
belonging to two defined systems. 
It has been generally assumed that these proper motions 
were proper to the individual stars only, but Prof. Kapteyn 
recently concluded that this assumption was erroneous, and 
that they might be classified into two “ drifts,’” which are 
in relative motion, the one to the other. Mr. Eddington’s 
results confirm this theory quantitatively. In each drift 
the velocities relative to the system of axes of the drift 
are quite haphazard, but this system of axes has a velocity 
which is defined as the velocity of that drift. 
On analysing the figures obtained for the regions dis- 
cussed, in order to find the directions of the two drifts in 
each region, Mr. Eddington found that the stars of drift i. 
have a common velocity, relative to the sun, away from 
a point near to R.A. 18h., dec. +18°, and that the best 
NO. 1938, VOL. 75] 
point for the apex of drift ii. is about the position R.A. 
7h. 30m., dec. +58°. The velocity of the first drift relative 
to the sun is much larger than that of the second, the ratio 
being about 17:5, and from an investigation of the magni- 
tudes of the proper motions there appears to be no appreci- 
able difference in the mean distances of the stars of the 
two drifts (the Observatory, No. 377). 
Tue SpECTROCOMPARATOR.—An extremely interesting in- 
strument, devised for the measurement of the spectral dis- 
placements in the determination of stellar radial velocities, 
is described by Dr. J. Hartmann in No. 4, vol. xxiv., 
of the Astrophysical Journal. 
The usual method employed in measuring the ‘‘ Doppler ”’ 
displacement has been to measure the displacement of each 
individual stellar line in regard to the corresponding line 
in a terrestrial spectrum, but in Dr. Hartmann’s instru- 
ment a large number of lines are compared with those of 
a standard solar spectrum at one time, so that a stellar 
spectrum rich in lines, which would, by the older method, 
have taken days to measure, may now be measured in an 
hour or two. Details, too numerous to mention here, are 
given in Dr. Hartmann’s paper, and are well illustrated 
by diagrams and worked examples. 
MEASUREMENTS OF THE EFFECTIVE WAVE-LENGTHS IN 
STELLAR SpectRA.—The position of the ‘‘ effective’ wave- 
lengths in stellar spectra, that is, the position of the 
radiations which, in the combined radiations of a complete 
spectrum, appeal most strongly to the eye, is of great 
importance in double-star observations. For this reason 
Dr. H. E. Lau has determined this position in seventy 
stars, by Prof. Comstock’s interference method, and pub- 
lishes the results in No. 4134 of the Astronomische 
Nachrichten. 
The stars which have been examined are arranged in 
groups according to the Harvard classification, and the 
distance between the conjugate spectra of the first order is 
given for each object. This quantity may be converted 
into wave-lengths by the application of a known factor. 
EarLty OBSERVATIONS OF JUPITER’S SIXTH SATELLITE.— 
On examining the Harvard photographs of Jupiter, Miss 
Leavitt found the image of the sixth satellite on two taken 
in 1894 and on nine taken in 1899. These plates were 
measured, and the results of the measures and their reduc- 
tion are given and discussed in No. ii., vol. Ix., of the 
Annals of Harvard College Observatory. It appears that 
Miss Leavitt marked and measured this satellite when 
examining some of these plates on December 10, 1904, but 
concluded that it was probably an asteroid near to its 
stationary point. 
OBSERVATIONS OF THE AuGust MetEeors.—In No. 4132 
of the Astronomische Nachrichten Prof. von Konkoly 
records the results of some meteor observations made at 
the O-Gyalla Observatory in July and August last. These 
results show that the maximum of the shower occurred 
on August 12, on the night of which 158 meteors were 
observed at O’Gyalla and 251 at the subsidiary station at 
Nagy-Tagyos. On August 13 the corresponding numbers 
were 111 and 175. 
GEOLOGY IN THE UNITED STATES AND 
CANADA. 
LACIALISTS will be interested in the short sketch 
of the drumlins of south-eastern Wisconsin contained 
in Bulletin No. 273 of the U.S. Geological Survey.’ It is 
a preliminary record of a detailed study of the post- 
Pleistocene deposits of the district which embraces part 
of the ground moraine of the Green Bay glacier—in which 
most of the drumlins lie—and part of that of the Lake 
Michigan glacier, as well as an earlier Iowan or Illinoian 
glaciation. The relations of the drumlins to eskers and to 
the terminal moraines and rock mounds were investigated. 
The map shows most clearly the arrangement of the 
drumlins to correspond with the lines of flow of the deploy- 
ing glacier. 
Bulletin No. 265? contains a short account of the struc- 
1 Bulletin No. 273. ‘‘The Drumlins of South-eastern Wisconsin.” 
(Preliminary Paper.) By W. C. Aldin. (1905-) 
2 Bulletin No. 265 ‘‘ Geology of the Boulder District of Colorado.” 
By N. M. Fenneman. (1905.) 
