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EXPERIMENTS USING THE FOUCAULT PENDULUM DURING THE SOLAR ECLIPSE OF 15 FEBRUARY, 1961 G. T. Jeverdan, G. I. Rusu and V. Antonesco Jassy University Rumania A
number of observations were made of the behavior of a Foucault pendulum during
the eclipse of the Sun of 15th February 1961. An
experiment was performed to measure the variations in gravitational
acceleration. The
pendulum’s features were as follows: o
length
25.008 meters. o
sphere’s
weight 5.5 kilograms with a diameter of 10 centimeters. To
avoid torsion of the ends of the wire, a connection was made by means of two
torsionless silk rings. The
pendulum was oscillated through an angle of 4°. To reduce the error during the period of oscillation, the average
was taken of three chronometers functioning simultaneously for 50 complete
oscillations. By
this method the average period was able to be determined within a margin of
error of ± 0.004 second. The
eclipse at Jassy (geographic coordinates: = 47° 11' N.; 1h 50m
14s E.) commenced at 8h 49m 3s.25
and terminated at 11h 16m 50s.35. The maximum effect, whose magnitude was
0.973 cm/sec2, took place at 10h 0m 37s.71
(official time in R.P.R.). During
the eclipse, the following average values were obtained for the period, T,
and the acceleration of gravity, g: --------------------------------------------- Time Observed Period g hours:min T (seconds) (cm/sec2) --------------------------------------------- 8:49 10.028 ± 0.004 980.78 9:13 10.028 ± 0.004 980.78 9:43 10.024 ± 0.004 981.56 10:00 10.019 ± 0.004 982.54 10:12 10.020 ± 0.004 982.34 10:24 10.024 ± 0.004 981.56 10:58 10.028 ± 0.004 980.78 11:10 11.028 ± 0.004 980.78 --------------------------------------------- (The time shown corresponds to the start of each phase.) It can
be seen that g reached its maximum at 10h. The
pendulum oscillated in the same plane until 10:08. At that moment a surprising fact occurred: the pendulum produced
a perturbation by describing an ellipse whose major axis deviated in relation
to the initial plane by approximately 15°.
The eccentricity of the ellipse was 0.18. At the end of the eclipse the pendulum continued to maintain the
elliptical oscillations, but the major axis approached increasingly to its
initial plane. A similar result
concerning a shift of the oscillation plane was obtained on 30th
June 1954 by Professor Maurice Allais at Saint-Germain-en-Laye. We have, however, only indirect information
regarding these experiments.[1] Conclusions A possible explanation of
the observed variation in g could be the following: During
the eclipse, the moon exerted a screening effect on the attraction
(gravitation) of the sun so that the attraction (gravitation) of the earth was
indirectly increased. The phenomenon
might also be studied by means of data regarding the tides, but such data is
not available to us. The deviation from
the pendulum’s oscillation plane can be explained by the same hypothesis. If the
hypothesis of the screening effect cannot be verified, the variation in g
might be considered as a result of diffraction of gravity waves. This latter hypothesis is only possible if
the dimensions of the moon are comparable to the wave lengths of the
gravitational waves. In which case the
mass of the gravitons would be approximately 10-46g (calculated by means of Compton’s
wavelength). These experiments should be
repeated during other total eclipses of the sun. [1]Evidently unbeknownst to the authors of the paper, the work was published: M. Allais, 1957. Report of the Academie des Sciences of 4 December. —Ed. |