Geophysical Abstracts 152 January-March 1953

20 GEOPHYSICAL ABSTRACTS 152, JANUARY-MARCH 1953
microscopic inclusions of magnetite) cause anomalous results. It is shown
that such inclusions are present in all the micas examined, and account for
the apparent pararnagnetism of synthetic mica. The inclusions are probably
oriented with their magnetic axes in a preferred direction relative to the
crystallographic axes of the mica. Authors' Abstract
14230. Le Borgne, Eugene. Sur le stisceptibilite magne'tique du sol [On the
magnetic susceptibility of soil]: Acad. Sci. Paris Comptes Bendus,
tome 235, no. 18, p. 1042-1043, 1952.
The magnetic susceptibility of samples of granite, schist, and soil from areas
around Pontivy and between Quimper and Quimperle were determined. The
susceptibility of the schist ranged from 8 to 18X10-6, and of the granite from
5 to 14X10~e. The susceptibility of the soil was -in general greater than that of
the underlying rocks, being of the order of 10~4 and sometimes reaching 10"* cgs.
M. C. R.
14231. Roche, Alexandre. Sur 1'origine des inversions d'aimantation constate"es
dans les roches d'Auvergne [On the origin of inverse magnetization
observed in the rocks of Auvergne] : Acad. Sci. Paris Comptes Rendus,
tome 236, no. 1, p. 107-109, 1953.
Rocks from the Monts d'Auvergne, France, showing reverse remanent mag­
netization have been heated to the Curie point and then cooled in a magnetic field.
The rocks showed a slow steady decrease of magnetization with increased-temper­
ature and when cooled took on a magnetization of the same direction as that
of the applied field. In addition to claystone beneath basalt flows and the
calcareous marl adjacent to a basalt dike have the same reverse remanent mag­
netization as the basalt. In two of these instances it has been shown that the
minerals contained in the claystone are syngenetic and are not related to the
vulcanism. Apparently these reverse magnetizations cannot have been produced
by the mechanisms proposed by Neel (Geophys. Abs. 13319) but must represent
real reversals of the earth's magnetic field at the time these rocks cooled. J. R. B.
INSTEtJMENTS AND METHODS OF OBSERVATION
14232. Balsley, James R. [Jr.] Aeromagnetic surveying in Advances in Geo­
physics, v. 1, p. 314-549, New York, Academic Press, 1952.
Instrumentation, field and office techniques, interpretation of results,
advantages and limitations, and uses of aeromagnetic surveying are reviewed.
M. C. R.
14233. Koulomzine, T. Magnetometer, U. S. patent 2,627,542, granted February 3,
1953. 6 claims.
A permanent magnet suspended from a float and emersed in a fluid so that
the center of gravity of the magnetometer balance system is below its center of
buoyancy.
14234. Haalck, F. Magnetometer, U. S. patent 2,629,003, granted February 17,
1953. 16 claims. Assigned to Askania-Werke A. G.
A magnet suspended from horizontal torsion wires.