The conditions for which a fluid sphere heated within and subject to the simultaneous action of a uniform magnetic field and rotation can become unstable via a marginal state of purely oscillatory motion are studied. Different from the results of the paper (Namikawa, 1957b), over-stability occurs both under astrophysical and terrestrial conditions.

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Magnetic viscosity of ensemble of medium-sized grains of natural magnetites was examined at various temperatures. It was found that magnetic viscosity coefficient S, defined as I-I₀=S(Q+logt) where I and I₀ are intensity of magnetization at time t and t=0, is proportional to external magnetic field, and S is a linear function of temperature, except at temperatures close to the Curie point and -160°C, so far as the Rayleigh region of magnetization is concerned. It seems also that S tends to a finite value according as grain size tends to the order of a single domain.
For ensemble of magnetite grains, S in expression of ΔI=S(Q+logt) is very small, and the limit of half life time τ for change in thermoremanent magnetization, expressed by τ=expI_tr/2S amounts to 10¹²⁰ years.
Further, the half life time for sedimentary rocks, in which directions of grain magnetization are scattered, with reduction factor w, is about 10¹⁰ years for w=1/5. These results may show that remanent magnetization of igneous and sedimentary rocks have been stable against thermal viscosity during a geologically long time.

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Simultaneous records of the atmospheric electric potential gradient at three stations which make a regular triangle with sides of about two km, were compared with each other during the period of January 8-13, 1956, including a cloudy day as well as fine days. Expanding the daily course of the potential gradient on each day and at each station into Fourier series of 12 terms, the spectral distribution of the square of the amplitude of each component was obtained and the spectrum of the field was given by n^-4 in an undisturbed day, n expressing the harmonic term. On theoretical grounds, assuming the distribution of space charge concentration characterized by its scale and its density within the lower layer of the atmosphere, the spectral distribution of field energy was suggested to be represented by n^-7 in the intermediate range of n. The result was proved to be consistent with the above analytical result. The factor causing the disturbance in the spectrum was looked for into the atmosphere using the aerological data. It was found that the turbulent situation of the air in the lower altitudes up to three km would control the structure of the atmospheric electric field.

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The temperature of transition of synthetic γ-Fe₂O₃ (maghemite) to α-Fe₂O₃ (hematite) is lowered by increasing pressure. The transition line is represented by the equation, p=150-0.3T, where p is pressure in bar and T is temperature in °C. The transition of Ti-bearing γ-Fe₂O₃ (titanomaghemite) needs higher pressure and temperature than that of pure γ-Fe₂O₃. From the experimental results, it is suggested that maghemite is formed only near the surface of the earth, probably at depths shallower than about 500m of the crust.

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It has been observed that the low energy cosmic rays are produced associated with solar flares and propagate into interplanetary space. In this paper, we examined the features of the propagation mechanism of these cosmic rays, taking into account the results deduced from the theory of geomagnetic effect on these low energy cosmic rays. In consequence, we can conclude that the features of their incidence to the earth must have the impact zone effects, G. M. T. effects, and seasonal variations. Then, we examined the relations between these low energy cosmic ray events and solar and terrestrial phenomena in view of the observed data and made clear that both of flares and type IV outbursts taking place on western side of the sun seem to correlate these cosmic ray events much better. Taking into account those results we tried to explain reasonably the propagation mechanism of these low energy cosmic rays into interplanetary space and in addition to estimate the properties of magnetic clouds in that space.

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The daily percentage variations of the air-earth current were calculated every longitude of 90° over the world, using the percentage variation of the potential of the upper conducting layer (atmospheric total potential) deduced from Carnegie measurements over the oceans, and that of the columnar resistance obtained from the measurements by Sagalyn and Faucher. The results generally represent the world-wide distribution of the measured daily variation curves which were arranged by Israël. This fact generally indicates that the daily percentage variations of the columnar resistance at the most stations over the land area are roughly equal, and also of the same magnitude as the universal daily percentage variation of the atmospheric total potential. However, more detailed discussions by comparing the measured and the calculated results at the urban district of the meridian 135° E show that the daily variations of the air-earth current depend more on the local columnar resistance than the atmospheric total potential, the percentage variation of the former being twice as much magnitude as that of the latter. It is suggested that at the urban district the unclei concentration in the lowest layer of the exchange layer plays an important part in the atmospheric electric current system.

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