SECTIONAL TRANSACTIONS.—A*, At. 459 
Tuesday, September 12. 
Joint Discussion with Section J (Psychology, g.v.) on The validity and 
value of methods of correlation (10.0). 
DEPARTMENT OF COSMICAL PHYSICS (At). 
Thursday, September 7. 
Dr. W. H. McCrea.—Problems of the solar chromosphere and corona (11.0). 
Survey of recent work, particularly Rosseland’s theory depending on the 
ejection of fast electrons by the sun. The possibility of such ejection. 
Mr. W. M. H. Greaves.—The observation of stellar colour temperatures 
(11.25). 
Dr. G. C. McVitt1r.—Non-static solutions, with singularities, of Einstein’s 
gravitational equations (11.50). 
Generalisation of Schwarzschild’s solution for a mass-particle, in the ex- 
panding universe theory. The choice of co-ordinate systems. The dis- 
tribution of matter outside the mass-particle. The cosmical constant. 
Dr. W. J. S. Lockyer.—Periodic changes in two Be-type spectra (12.15). 
One of the researches which is being carried out at the Norman Lockyer 
Observatory at Sidmouth is the spectroscopic study of some of the brighter 
stars of the Be type—i.e. those stars which exhibit bright hydrogen lines in 
their spectra. This work was commenced in the year 1923, and has been 
continually pursued since then. 
The Sidmouth research has been chiefly confined to the determination 
of the changes in the relative intensities of the bright components of each 
of the hydrogen lines, for each hydrogen line consists of a broad absorption 
band on which are superimposed two bright lines, separated by a strong sharp 
absorption line. These intensity differences are determined by two methods 
—one by eye-estimates under a small magnifying power ( x 2), and the other 
by a wedge-micrometer. The results are here given for two stars only, to 
illustrate the methods. The first deals with the star 7 Persei, of magnitude 
4°19, for which a period of change of 126°8 days is deduced. The character 
and intensities of several absorption lines in the spectrum are also discussed. 
The second star, y Cassiopeiz (mag. 2:o1), is a star the spectrum of which 
has never before been detected to exhibit any change. Distinct variations 
are here indicated, and a probable variation of about four years in length 
is clearly indicated. 
Mr. A. D. Tuackeray.—The measurement of line intensities in stellar 
spectra (12.40). 
Stellar spectra for the measurement of line intensities have to be 
standardised photometrically in order to relate the photographic density to 
the intensity of the original incident light. Many photographic errors may 
arise due to differences in stellar and standard exposures, and especially to 
