304 
NATURE 
[JANUARY 24, 1907 
OUR ASTRONOMICAL COLUMN. 
Tue Prorer Motion or Castor.—Taking into account 
both the true proper motion and the orbital motion of the 
system of Castor, Mr. Crommelin has determined a new 
value for the proper motion of the centre of gravity of 
the system. This new value is —o-0135s., +0"-120, and 
it represents the facts much more closely than those 
previously determined by Auwers and Newcomb _ respec- 
tively. In fact, the latter would have become entirely 
erroneous, in N.P.D., within a few years, for they were 
based on the assumption that the proper motion was 
uniformly rectilinear, whereas the orbital motion in 
N.P.D. will, in a few years, be entirely reversed. It is 
interesting to note that the new value was obtained by 
taking into account the spectroscopic as well as the 
meridian-observation results, and that the mass ratio 
obtained by Dr. H. Curtis, which shows that the mass 
of ar is six times greater than that of a2, is hereby 
confirmed (Monthly Notices R.A.S., December, 1906). 
Line INTENSITY AND SpEcTRAL Typr.—The results of an 
interesting investigation of compound lines shown on the 
stellar spectrograms obtained at the Mills Observatory, 
Chile, are published in No. 5, vol. xxiv., of the Astro- 
phystcal Journal by Dr. Sebastian Albrecht. From the 
spectrograms of stars of different types it was found that 
certain compound lines give progressive differences in the 
determined radial velocities as one passes from the type 
F to the type Mb in the Harvard classification. The in- 
vestigation showed that these differences are probably due 
to the variation of intensity, rather than the presence or 
absence, of the same components of the blended line in 
passing from one stellar type to another. It also showed 
that, considering the origins of the variable lines, the 
physical conditions in the stars as we pass from the F 
(Procyonian) to the Mb (Antarian) type vary roughly in the 
same direction as from the sun to the sun-spots, a con- 
clusion confirming that arrived at by Sir Norman Lockyer 
(Proc. Roy. Soc., vol. Ixxiv., p. 53) in a paper which does 
not appear to have been noted by the American observers 
who have since dealt with this subject. 
The awkwardness of having an arbitrarily chosen code, 
instead of self-explanatory generical names, to represent 
stellar types, is strikingly illustrated in the present paper, 
where the reader’s mind is constantly taxed in trying to 
remember the significance of such signs as Ma, K,M, F,G, 
and so on. 
SILICON IN THE CHROMOsPHERE.—At the last meeting of 
the Royal Astronomical Society, Mr. Fowler read a paper 
in which he demonstrated the probable presence of silicon 
in the chromosphere. This element was identified by the 
presence of two ofits strong lines, A 6347-3 and A 6371-6, 
as well-marked lines in the chromospheric spectrum. Both 
lines occur in the Fraunhofer spectrum, with intensities 
and characters 2N and 1Nd? respectively, and the latter 
was ascribed to iron by Rowland, who failed to find an 
origin for the other. Both are probably enhanced lines, 
and are almost obliterated in the sun-spot spectrum 
(Monthly Notices, No. 2, vol. Ixvii.). 
VARIATION OF WAVE-LENGTHS IN THE SOLAR SPECTRUM. 
—Whilst discussing his 1901-6 observations of the sun’s 
rotation period, Dr. Halm discovered a previously un- 
known “‘ shift’ in two of the spectrum lines employed. 
The method used at Edinburgh is that in which the differ- 
ence of the interval between certain solar and atmospheric 
lines at the sun’s centre and at the limb is measured, this 
difference giving the ‘‘ Doppler ’’ displacement at the limb 
due to the sun’s rotational! motion. Dr. Halm found that 
this interval was not the same in 1906 as in 1901, and on 
analysing his results further he also found some indication 
of a three-year period in the variation, thus giving addi- 
tional confirmation to the existence of a short period in 
solar phenomena such as found by Dr. W. J. S. Lockyer 
when discussing the relations between solar and terrestrial 
meteorological phenomena. Dr. Halm suggests that the 
“shift ’’ discovered by him may be due to difference of 
pressure (Astronomische Nachrichten, No. 4146). 
NO. 1043, VOL. 75 | 
MEETING OF THE AMERICAN ASSOCIATION 
AND ITS AFFILIATED SOCIETIES. 
HE fifty-seventh meeting of the American Association 
for the Advancement of Science and of the societies 
affiliated with it was held at New York, N.Y., during. the 
recent convocation week (December 26, 1906, to 
January 2), under the presidency of the distinguished 
pathologist Dr. William H. Welch, of Johns Hopkins 
University. The meetings brought together a _ larger 
number of scientific men than ever before, and it is 
estimated that about 1800 scientific men and women were 
in attendance. The meetings for the most part were held 
in the compact group of buildings forming the Morning- 
side Heights property of the Columbia University, but 
the medical meetings of Section K (Physiology and Experi- 
mental Medicine) of the association, of the American 
Physiological Society, the American Bacteriological Society, 
and the American Society of Anatomists were held at the 
College of Physicians and Surgeons and at the Rockefeller 
Institute. The Geological Society of America and 
Section E (Geology and Geography) met at the American 
Museum of Natural History, and the Botanical Society 
of America and Section G (Botany) met at the Botanical — 
Gardens. The opening meeting was held in Earl Hall, 
Columbia University, when the retiring president, Prof. 
C. M. Woodward, of St. Louis, introduced his successor, 
Dr. William H. Welch. An address of welcome was given 
by Dr. Nicholas Murray Butler, president of Columbia 
University, to which Dr. Welch responded. 
The address of the retiring president, Prof. Woodward, 
was delivered at the Teachers’ College on Thursday night, 
December 27, 1906, and was entitled ‘‘ The Science of 
Education,’’ a peculiarly apt topic for this meeting, since 
a new section, ‘‘ L—Education,’’ was founded at this 
time. 
The addresses of vice-presidents, that is, the chairmen 
of sections, were- extremely interesting. On Thursday 
afternoon Vice-president Ward, in his address before the 
Section of Zoology, used as his subject ‘‘ The Influence 
of Parasitism on the Host ’’; Vice-president McNair, before 
the Section of Mechanical Science and Engineering, spoke 
on ‘“‘ Some Problems Connected with Deep Mining in the 
Lake Superior Copper District ’’; Vice-president Fisher, 
before the Section of Social and Economic Science, spoke 
on the topic, ‘‘ Why the Latsser-faire Doctrine Failed ”’ ; 
Vice-president Rice, before the Section of Geology and 
Geography, spoke on ‘‘ The Contributions of America to 
Geology ’’; Vice-president Sedgwick, before the Section of 
Physiology and Experimental Medicine, spoke on ‘* The 
Expansion of Physiology ’’; Vice-president Eichelberger, 
before the Section of Mathematics and Astronomy, had as 
his title *‘ Clocks—Ancient and Modern’’; Vice-president 
Mabery, before the Section of Chemistry, spoke of the 
“Education of a Professional Chemist ’’; Vice-president 
MacCurdy addressed the Section of Anthropology on the 
subject of ‘‘Some Phases of Prehistoric Archeology ’’; 
Vice-president Crew, before the Section of Physics, spoke 
on “‘ Fact and Theory in Spectroscopy ’’; and Vice-presi- 
dent Smith, before the Section of Botany, under the title 
“Problems in Plant Pathology.”’ 
One of the most interesting and important features of 
the meeting was the holding of a number of joint sessions 
between different societies and sections. For example, the 
afternoon of December 27 was devoted to a symposium 
under the auspices of Section K (Physiology and 
Experimental Medicine) at the College of Physicians 
and Surgeons on the subiect of protozoa as factors in 
disease, a discussion in which both the pathologists and 
the botanists joined. On the following day a joint meet- 
ing of the Society of Zoologists and the Sections of Zoology 
and Botany was held for the reading of papers on heredity 
in plant and animal breeding, and on that day Section K 
held a joint meeting with the Society of American Bacterio- 
logists. There was also a general discussion under the 
auspices of the American Society of Naturalists on the 
general topic “‘ The Biological Significance and Control of 
Sex.’”’ On the same day a new Entomological Society of 
America was founded, with nearly 200 members, and a 
public lecture was delivered under its auspices by Dr. 
