The daily mean intensity of cosmic rays and geomagnetic horizontal component are measured from the 27-day running average values, and this measure of disturbance is named “variability.” The frequency distribution of variability for both cosmic rays and horizontal component deviate from the normal distribution toward negative, and this character is nearly the same amount for two cases throughout one sunspot cycle from 1936 to 1945.
The maximum value of cosmic-ray variability delays from the sunspot maximum. Since the circumstance is nearly similar to that of horizontal component, it may be said that a large number of the cosmic-ray disturbance observed at the sunspot maximum time is due to the phenomena related to the magnetic disturbances.
Though there are several evidences which indicate the close relation between cosmic-ray and geomagnetic variability, apparent difference is seen at the period of sunspot minimum. It suggests that there is some kind of magnetic disturbance which is independent of cosmic-ray variation.

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The detailed mechanism of the self-reversal of thermo-remanent magnetism of rocks was studied. The ferromagnetic mineral grains responsible for this phenomenon were determined as A′B-grains, which consist of two constituents, A′ and B. The magnetic and crystallographic examinations of Haruna rocks showed that the constituent with higher Curie point, in the two-constituent model, should be estimated to be a solid solution between ilmenite and hematite, and not the Ti-poor titanomagnetite as was estimated to be in the previous studies. In other words, the magnetic interaction causing the self-reversal of thermo-remanent magnetism is between two ilmenite-hematite solid solutions with different Curie points. Electron-microscopic observations showed that the constituent with higher Curie point is intergrown into the constituent with lower Curie point as fine lamellae. The observed configurations of these two constituents indicated that the phenomenon of reverse thermo-remanent magnetism could be explained theoretically, provided that the grains as fine as the observed lamellae have very strong thermo-remanence.
Similar examinations were conducted on ferromagnetic minerals of several other rocks with the same mineral assemblage as the Haruna ferromagnetic minerals. The results of these examinations indicated that there exist, in natural ferromagnetic minerals, various degrees of magnetic interaction which are governed by their state of co-existence.

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The susceptibility and remanent magnetisation have been determined for seven representative samples of the granodiorite, granite and basic enclaves which form the bulk of the Arrigle Complex, lying at the south-west termination of the Leinster Granite. The determinations were made on the rocks in their natural state and again after they had been heated to 600°C and cooled in the earth's magnetic field in London. From these have been calculated X, the ratio of the susceptibility after and before heating; S, the ratio of the thereto-remanent magnetisation to the remanent magnetisation; and Z, the ratio of Q to T.
For the granodiorites, X averages about 30 and S about 50; this indicates that new magnetic minerals were developed by heating and suggests that the granodiorites, as now constituted, have not cooled through their Curie point. For the granites, X averages 1.3 and S about 32; this indicates that no new magnetic minerals have been developed by heating, but that the remanent magnetisation of existing magnetic minerals has been greatly increased. This proves that the magnetic minerals of the granite have formed below their Curie point; the petrography indicates that magnetite has formed or reformed along with other deuteritic changes, the most important of which is the change of hornblende to a biotite-quartz symplectite. Of the basic enclaves, the gabbroes show X equal to 1.6 and S equal to 2.7; this proves that the gabbroes have crystallised and cooled from above their Curie point in the normal manner of igneous rocks. Another enclave, supposedly a porphyretic dolerite, shows X equal to 3.9 and S equal to 21; either the dolerite has suffered much low-temperature metamorphism of its magnetic, or potentially magnetic, minerals, or it is a metamorphic rock closely resembling a dolerite.
Thermo-magnetic investigations, combined with petrography, along the lines outlined in this paper should prove of great assistance in the elucidation of the thermal history of many metamorphic-plutonic-igneous rocks.

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An attempt is made to examine the energy gain or loss of the primary cosmic ray produced by an electro-magnetic field of solar stream, and then to explain the diurnal variation of cosmic rays at the time of the magnetic storm by this energy variation of cosmic rays.
The amplitudes and the times of the maximum intensity of the diurnal variations are calculated at various altitudes and latitudes by using the above mentioned electric field.
Whether the diurnal variation of cosmic rays averaged over all days can be explained or not from the standpoint of the electric field hypothesis is also discussed.

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