The seasonal variation of the water temperature of 12 rivers in this country observed in 1931 and 1932 was examined. From the difference between the temperatures of water-and air the following three river-types are recognized. A. Lower type: The period in which the water-temperature is lower than the mean air temperature is limited only for 1 or 2 months of the summer and moreover the difference of both temperatures is below 2°C. (R. Kawadana at Nagasaki, R. Asahigawa at Okayama, R. Arakawa at Kumagaya and R. Kitakami at Isinomaki) B. Middle type: The period above mentioned is for 5 or 8 months of the warmer seasons and the difference is above 4°C. The minimum water-temperature occured in February. (R. Arakawa at Titibu, R. Kinugawa at Utunomiya, R. Tikumagawa and R. Saikawa at Nagano and R. Mogamigawa at Yamagata.) C. Upper type: The period is further widened to the almost all months of the year and the high period of water-temperature is only for 1 or 3 months of the winter. The difference of both temperatures is greater than that of the middle-type. (R. Hirosegawa at Maibasi and R. Susohanagawa at Nagano.)
This paper is a brief preliminary report of earth-current observed at Kakioka and Toyohara from Aug. 1932 to Aug. 1933, the 2nd polaryear. Comparing records at both places, we have found a striking similarity in spite of their geographical and geological differences. The diurnal variation curve has two maxima at 4h a. m. and 2h p. m., and at Kakioka, the east-and north-components have mean ranges of 0.78 and 0.50 millivolts per 100m respectively, while at Toyohara, 0.73 and 0.29 millivolts. It is interesting that the general direction of diurnal variation is SW-NE, approximately directing to the magnetic northpole as at some other places in the world. We try to explain a pretty large variation in earth-current accompanied by thunderstorm or shower, but earth-magnetism does not so large variations. By a simple calculation, it was found that this current does not flow deeper than 800m beneath the earth surface, supposing a mean resistivity of the soil is 104 ohms per cm.
It is well known that the variations of earth current correspond to those of terrestrial magnetism, but there are few quantitative studies of them except the diurnal variations. The author investigated the ratio of the amplitudes of their variations, using the data at Toyohara for the period from August 1932 to July 1933 and found that the shorter the period, the larger the ratio, and that this ratio is roughly proportional to T-0.4 where T denotes the period. Next, considering the east-west component of earth potential gradient induced by the horizontal component of terrestrial magnetism, so far as the variations are concerned, we theoretically calculated the ratio of the amplitudes and the result is in a good accordance with the observed fact.
§1. Introductory, -What is and what should be the theory of cracks? §2. Systematics, -Systematic classification of cracks. §3. Morphology, -Study of the form and the structure of cracks. §4. Ontogeny, -Study of the genesis of cracks (see e. g. from Fig. 5 to Fig. 34). §5. Physiology, -Physical and chemical explanation of phenomena relating to cracks.
The phenomenon that the aeroplane seems to be repulsed when it approaches to a mountain and attracted when it crosses over a valley, is explained hydrodynamically by M. Sanuki.(2) In this paper, when we assume that a mountain-shape is conformally represented by the following conformal function, in which λ, α, β, γ are constants, we obtained approximately F (_??_) as the term of the “Topography Effect”, where, assumming the aeroplane as a point-vortex, _??_ is its co-ordinate. As an application, lift and drag above the summit of Mt. Huzi are calculated.