Geophysical Abstracts 152 January-March 1953

18 GEOPHYSICAL ABSTRACTS 152, JANUARY-MARCH 1953
magnetic disturbances. Magnetoinductive equipment of high sensitivity, capable
of registering variations of the vertical magnetic component as small as 10~8
oersted, was used.
As meteors reaching the earth's atmosphere produce large electric charges,
they were traced and observed by radar instruments that permitted their obser­
vation both night and day.
A magnetic effect of meteors on the regional geomagnetic field was established
in about 30 percent of the observed cases. More sensitive equipment might im­
prove this correlation, but some of the meteors are too small and their distance too
great to produce a noticeable effect. S. T. V.
14223. Kirkpatrick, C. B. On current systems proposed for 80 in the theory of
magnetic storms: Jour. Geophys. Research, v. 57, no. 4, p. 511-526,
1952.
A theoretical current system, similar to the models proposed by Birkeland and
Alfve"n as sources of geomagnetic disturbance, is analyzed, and the magnetic field
produced by it is compared with the observational data and the fields of other
theoretical models. The results indicate that the Birkeland model, which has
been rejected by Vestine and Chapman, and Alfven's model are unsatisfactory as
sources of the daily variation (So) of geomagnetic disturbance. Some general
principles are developed for use in the field analysis of current systems.
Author's Abstract
MAGNETIC PROPERTIES OF ROCKS AND MINERALS
14224. Nagata, Takes[h]i, Akimoto, Syun'iti, and Uyeda, Seiya. Reverse ther-
moremanent magnetism: Acad. Japan Proc., v. 28, no. 6, p. 277-281,
1952. J
A previous article (see Geophys. Abs. 14028) discussed the observed self re­
versal of thermoremanent magnetization of a hypersthene hornblende dacitic
pumice from Volcano Hasuna, Japan. This rock when subjected to a magnetic
field while being cooled from 500 to 450 C shows normal thermoremanent mag­
netization but when reheated exhibits an abnormal increase of magnetization at
450 O similar to that proposed by Neel for P-type ferrites. When subjected to a
magnetic field while being cooled from 300 to 250 C the rock demonstrates re­
verse thermoremanent magnetization with a positive temperature coefficient of
magnetization marked by larger than the negative temperature coefficient of the
normal thermoremanent magnetization. This suggests that N- or V-type ferrites
exist in the specimen and possibly are responsible for the reverse thermoremanent
magnetization. J. R. B.
14225. Nagata, Takes[h]i, Uyeda, Seiya, and Akimoto, Syun'iti. Self-reversal
of thermoremanent magnetism of igneous rocks: Jour. Geomagnetism
and Electricity, v. 4, no. 1, p. 22-28. 1952.
The general conclusions reported in previous articles (see Abs. 14026, 14028,
and above) are presented in more detail. J. R. B.
14226. Neel, Louis, and Pauthenet, Ren6. iDtude thermomagnetique d'un mono-
cristal de FeaOsa[Thermomagnetic study on a single crystal of aFesO»] :
Acad. Sci. Paris Comptes Rendus, tome 234, no. 22 p. 2172-2174, 1952.
Measurements have been made in the range 20.4 to 950 K of the variation
with temperature of the specific magnetization and susceptibility along the