Ss 
SECTIONAL TRANSACTIONS.—A. 337 
centrating its efforts on Fort Rae. A scientific assistant from the Meteorological 
Office has already visited Fort Rae this summer and made preliminary arrangements 
for a party to be housed and fed next year. The party will consist of three scientific 
men, one observer and one mechanic. It will leave England in May 1932 and 
commence observing on August 1. Observations will continue until the end of 
August 1933 when the party will return to England. 
A detailed plan of observations and a scheme for publishing the results have 
already been drawn up by the International Commission for the Polar Year 1932-33 
to ensure that all stations will make comparable observations and publish them in 
uniform style. 
Prof. Dayton OC. Mitter.—Lther-drift Experiments in Cleveland in 1930. 
The Ether-Drift Interferometer, previously used on Mount Wilson in California 
from 1921 to 1926, has been remounted on the campus at Case School of Applied 
Science in Cleveland. Some minor improvements have been adopted, such as shock- 
absorbing pads on the supporting piers, to eliminate traffic vibrations, and added 
precautions haye been taken to eliminate temperature disturbances. The methods 
of making and reducing observations are so devised as to remove the possibility of 
instrumental or terrestrial disturbances, and the observed effects seem to be cosmic 
in origin. As before, the interferometer has a sensitiveness represented by a light 
path of 214 feet, or about 130,000,000 wave-lengths of light. The numerical results 
are reliable to the hundredth part of a wave-length of light, corresponding to one-half 
of a kilometer per second of relative motion of the earth and the ether. 
A series of experiments recently completed gives results wholly in accord with 
those previously obtained at Mount Wilson; the observed effect is such as would 
be produced by a relative motion of the earth and ether of about 10 kilometres per 
second. The direction of the indicated motion is fixed with relation to sidereal time, 
that is, it is towards a fixed point in space, as of a motion of the solar system towards 
the point having a right ascension of 17 hours, and a declination of 68 degrees north. 
Ether-Drift produces an effect, as observed in the interferometer, which is pro- 
portional to the square of the ratio of the velocity of the cosmic motion of the earth 
and of the velocity of light; this is a ‘second order’ effect, and is periodic in each 
half revolution of the interferometer. The complete theory of this experiment, given 
by Hicks in 1902, shows that there is necessarily also present a first order effect, periodic 
in each full turn of the interferometer; this has never before been taken into accownt, 
but it is now shown that this effect is always present, and that it is in accord with 
the theory ; and it is considered as further evidence of the validity of the present 
experimental results. 
A discussion of the significance of these observations as compared with the recent 
work of other observers will be given. 
It is interesting to note that the present interferometer is mounted about 300 feet 
from the location of the original Michelson-Morley interferometer of 1887. Contrary 
to a prevalent opinion, the original observations of Michelson and Morley gave a small 
positive effect which is almost exactly of the same magnitude as that obtained in the 
present experiment. ‘Therefore the Michelson and Morley experiment fully agrees 
with the present results, though at the time it was differently interpreted. 
Attention is called to the results of several recent important experiments in diverse 
fields which seem to corroborate the indicated cosmic motion of the solar system. 
For table see next page. 
Dr. Ceca H. Payne and Dr. H. Saaptey.—The Harvard Photographic 
Photometry. 
The paper contains a report on the first instalment of the Harvard catalogue of 
photographic magnitudes, which is designed to be complete to 8.25 over the whole 
The photographic magnitudes are derived from plates taken with a 3-inch Ross 
lens, and measured with a Schilt thermoelectric micro-photometer. 
The first instalment of the catalogue, from +90° to -+-65°, has been completed ; 
it contains about two thousand stars. A comparison has been made with the 
following catalogues that cover the same region of the sky : the Greenwich catalogues ; 
1931 Z 
