372 NATURE 
[JULY 22, 1915 

the Prayer Book tables, Some account is also given 
of the Jewish calendar, with some reference to the 
astronomical evidence bearing on the date of the 
Crucifixion. The paper was followed by a discussion, 
which is reproduced with it. 
Dr. Downing expresses himself in favour of making 
Easter Day a Sunday in a fixed week, remarking that 
the lengthy explanations required by the present system 
make a strong argument in favour of this course. 
But, as he admits, no change is feasible which does 
not carry with it universal agreement. It is a little 
difficult to appreciate the opposition to a fixed Easter, 
which found expression in the discussion following the 
paper. The association of ecclesiastical festivals with 
certain astronomical conjunctions is intelligible, even 
if it fails to carry sympathy. But this. is precisely 
what the present artificial rules do not secure, a fact 
illustrated in the year 1905, alluded to by Dr. Down- 
ing, when Easter Day fell four weeks later than it 
should have done according to the real moon, and also 
by the complete variance between the Eastern and the 
Western churches. The opposition between religious 
sentiment and practical convenience would probably 
change in form if, instead of suggesting a fixed Easter, 
it were proposed to fix the dates of all public holidays, 
and so to dissociate them from all religious obsery- 
ances. 
CEPHEID-GEMINID VARIABILITY.—In the Astrophysical 
Journal (vol. xli., No 4, pp. 307-14) Mr. C. D. Perrine 
brings forward a tentative explanation of this type of 
stellar variability based on an inquiry into their orbital 
characteristics, etc. Discussion of data regarding 
thirteen stars indicates that the conditions requisite for 
the production of such variables are large eccentricity 
combined with small distance between components and 
small mass of secondary. The few cases of F- and 
G-type stars other than the variables in question with 
similar masses of secondaries and orbital dimensions 
have small eccentricities and show no variation in 
brightness. It is therefore suggested that the varia- 
tion of light is caused chiefly by changes in the light 
of the secondary due to disturbance in the part of its 
orbit near periastron, the maximum of light occurring 
at about the time of maximum approach of the 
primary. 
VARIABLE STARS.—A series of notes and data dealing 
with various subjects related to stellar variability is 
contributed by Dr. Harlow Shapley to the Astro- 
physical Journal (vol. xli., No. 4, pp. 291-306). Some 
of the observational work was carried out at the 
Princeton University Observatory, but the material 
was worked up at Mount Wilson. Using the bolo- 
metric observations of the Astrophysical Observatory 
of the Smithsonian Institution, Dr. Shapley has’ been 
able to investigate the darkening towards the limb of 
the sun in comparison with the similar darkening 
revealed by the study of eclipsing binaries. It has 
now been found that, although the empirical formula 
adopted at Princeton in the case of eclipse variables 
does not completely represent the solar darkening, the 
agreement is nevertheless quite close, the error being 
generally less than 1 per cent. It is also found that 
the darkening coefficient varies with the number of 
sun-spots, more especially for light of shorter wave- 
lengths; a variable darkening coefficient is thus sug- 
gested. Another note contains some interesting con- 
clusions regarding the periods and spectra of close 
binary stars. The data employed by Wicksell in a 
similar investigation has been legitimately extended 
by the inclusion of eclipsing variables. Cepheid vari- 
ables were, however, eliminated, Dr. Shapley having 
come to the conclusion that they are not binary systems 
(see Nature, vol. xciv., p. 572). Thus modified, the 
data does not show the secondary maxima of period 
found by Wicksell, except in the case of B-type stars. 
NO. 2386, VOL. 95] 
The maximum number of periods are between 2-5 and 
6 days. Other notes deal with variable stars 
U Pegasi, o Persei, R. Canis Major, and AE Cygni, 
and the number of naked-eye variables. 


THE SOCIETY OF CHEMICAL INDUSTRY. 
HE Manchester meeting of the Society of Chemical 
Industry on July 14-16 was by far the most 
important gathering of chemists since the commence- 
ment of the war, and its success augurs well for the 
future of the society. Hitherto the annual meetings 
have been largely of a social character, and though 
they have served a valuable purpose in promoting 
personal friendships, it has been widely felt that the 
society has not taken full advantage of the opportuni- 
ties for the discussion of industrial problems which the 
annual meetings provided. It was obvious this year 
that social functions were entirely out of place, and 
the organising committee devoted their efforts to secur- 
ing discussions of matters of prime importance to 
British chemical industry. 
At all the sittings, and still more in the general 
conversations, there was a consensus of opinion that 
the time had come for thé society as a body to take 
active action in regard to these matters. The gather- 
ing was a representative one, and was largely attended 
by the industrial chemists of the Manchester and 
Liverpool districts, and also by those further afield, in 
spite of the calls on their time made by war work. 
The academic element was very well represented, a 
noticeable feature being the presence of many of the 
professors recently appointed to act in a consultative 
capacity to the national dye scheme. Although visits 
to chemical works did not form part of the official 
programme, there was marked evidence on the part of 
manufacturers to oblige in this respect, showing that 
the need of greater co-operation amongst our chemical 
industries to meet foreign competition was not over- 
looked. 
The themes underlying all the papers, as well as 
Prof. G. G. Henderson’s presidential address, were the 
same—the need of closer co-operation between the 
manufacturer and the chemist, and the necessity of 
improving the training, not so much of the would-be 
chemist, as that of the managing classes of the com- 
munity so as to bring about a better appreciation of 
what science and scientific method really are, and how 
they can be turned to practical account. Not less 
important is the necessity of organising industrial 
chemists as a whole, so that they can speak authorita- 
tively and with a certainty of being heard in the 
counsels of the nation. : 
The discussions were to the point, and were brief, 
largely because the meeting was in entire agreement 
with the suggestions before it. A greater public par- 
ticipation in them by the representatives of industry 
might have produced new facts and suggestions, and 
the president should have made a more direct appeal 
on these grounds. Judging from what was said in 
private, the view-point of the man engaged in industry 
is imperfectly appreciated by the professor, and as the 
latter is more generally heard on the public platform, 
there is a danger of the practical side of the issues 
being insufficiently represented. This is particularly 
the case in regard to the many committees appointed 
in connection with the war, on which the chemical 
manufacturer is very inadequately represented. 
Prof. Henderson, in his presidential address, con- 
sidered that the comparative failure of chemical indus- 
try in this country was due to the lack of appreciation 
of research, to the absence of co-ordination between 
manufacturers and professors of chemistry, and 
especially to the lack of provision for enabling men of 
; academic training to apply their knowledge to indus- 

