In Japan, where a dense population is crowded together on a few small plains, it is not surprising that the use of sloping land in the mountains, which comprise 67% of Japan's area, has been promoted in various ways. In some regions the cultivation of steep land is amazingly intense. In this essay, only upland fields of considerable slope are discussed. The categories treated are 1) the steep field as a special type of upland field, 2) the regional distribution of steep upland fields, and 3) the problems of their future development. 1. Upland fields in general are subordinate in importance to paddy fields, but in some regions they are of first. importance. Broadly speaking, there are two sorts of upland fields, those on flat elevated land, and those on steep slopes. A survey was made in 1942 to classify upland fields by degree of slope, as follows : those with 5° of slope, those whith 5°-15°, and those with more than 15° of slope. Those in the latter category comprised about 50, 000 hectares, or nearly one-fifth of the total area of all upland fields. In fact, the greater part of these had a declivity of 20°-30°, and some reached 35° of slope. The soils of these fields, which comprise 2% of the mountain lands of Japan, are infertile lithosols. Figures 1 to 4 show the distribution of steep upland fields : Figure 1 ……the ratio of steep fields to all upland fields, by prefecture ; Figure 2 ……the ratio of upland fields to all cultivated fields ; Figure 3 ……the ratio of steep fields to all upland fields, by gun (district); Figure 4. ……the relative density of steep fielde to total area. The most important steep upland field regions are the mountainous regions in the Outer Zone of Southwest Japan, namely Shikoku and the Kii Peninsula ; the Inland Sea Region in the Inner Zone ; and peninsular regions of Kyushu. The mountainous regions of Central Japan are secondary to the above areas in importance. 2. The development of steep upland fields has been mainly related to self-sufficient food crops both on intensively cultivated permanent fields and on the much less important extensively cultivated shifting fields. Two morphological types of land use are distinguished : a) use of the natural slope with no modification, a type prevalent in Central Japan, and d) modification by terracing, a type dominant in Southwest Japan. In the use of natural slopes, contour cultivation is strictly adhered to, and much organic material is added to maintain the soil fertility. The yield of crops such as barley, wheat and soy beans is higher on these fields than on terraced fields. Mulberry trees are grown in large areas, and in some localities the Konnyaku tuber (Amorphophallus konjac) is grown intercropped with barley. On terraced slope lands, bench terraces are constructed on the steeper slopes, an sloping terraces on the less steep slopes. Typical examples of these are seen in southwest Shikoku. The strong intensity of precipitation is one of the most important factors that make steep land cultivable only by making terraces. The main crops are barley and wheat in winter, and sweet potatoes in summer. These terraces are subject to soil erosion on the one hand, and to drought on the other, , resulting in meager yields of all crops except sweet potatoes. 3. To improve the utilization of steep lands by agriculturists, it is necessary to plant profitable cash crops, such as sweet oranges, konnyaku tubers, and mulberry trees. The fundamental weakness, of steep upland field cultivation lies in the extensive cultivation of self-sufficient food crops, which require much labor per unit of area, and yield relatively little in return.
The temperature of irrigation water is very important for the growth of rice-plants, but it is sometimes too cold in the earlier stage of irrigation season in Hokkaido. Whereas the annual average of ground-water temperature is usually higher than that of river water in the district concerns. Ground-water may be thereby possiblly more profittable than surface water for irrigation in some period. Then the author investigated the temperatures of river waters and ground-waters to know when temperature of river water overruns that of ground-water in the district concerns in 1950. As the results, the followings were learned. Generally speaking, water temperatures of river seem to be 27°C in maximum, and are higher in lower reach than in upper reach, in main stream than in tributary at confluence, snd also in rivers flowing southward than those flowing northward. And they vary diurnally and annually, but their diurnal variations are less than 7°C and smaller by far than those of atmospheric temperature. And the maximum and the minimum appear from 1 to 3 hours later than those of air, and the temperature is the lowest during from 4 to 6 o'clock a.m, and the highest during from 3 to 4 o'-clock p. m. However the variation is very small in such rivers as Tomakomai river, having springs in source. The temperature falls down as a rule for a while in the middle or the last decade of May in Hokkaido. If a river water is taken in tunnel, it sometimes gets warm due to the temperature of the ground, but sometimes becomes cool, because it is not heated by sun. On the other hand, temperatures of ground-waters are related with those of air and river, and they are in general higher in lower reach, in southern regions, and in the districts, where temperatures of air and river are high, and furthermore, they seem to be high in the area descending southward. The temperatures of free or shallow ground-water are ranged from 5°C to 14°C, and their annual averages are usually 1°C or 2°C higher than those of atmospheric temperature in the district concerns. While temperatures of deep-seated confined ground-waters are in common from 8.5°C to 16°C, and show the geothermal gradients of from 25m. to 40m. for 1°C. The gradients seem to be larger in Pleistocene or Pliocene series than in Alluvial series. Comparing temperatures of river waters with those of ground-waters, river waters mostly overrun ground-water in temperature in the first or the middle decade of May. Then it seems not to deserve to use ground-water specially for irrigation. However temperatures of ground-waters are extraordinarily high in the lower reach of Ishikari river and in Takikawa Town, and they are higher than surface waters even in the middle of June. The ground-water temperature in Sapporo City is higher than that of Toyohira river before the middle of June. The waters of Tomakomai river and Horonai river become warmer than the ground-water in the district concerns in July. And the temperature of Chubetsu river is lower than the ground-water in the district even in the middle of June, so far as those of night concerns. Accordingly further study seems to be necessary for utilization of ground-water in these districts.
Needless to say, the fundamental technical development is necessary in order to progress natural sciences. The writer considers that the development of basic technique is very necessary particularly for the progress of geophysics in the present conditions. From this point of view, he cites two examples. One of them is on the apparatus of seismic explorations and the other is on gravimeters.
Rare large crystals of Enargite are newly found from Kaize, Nagano Pref., Japan. Their mineralogical notes are reported. Maximum size of crystals is 45 mm in caxe, and average is 1520 mm. New data of Two-circle goniometric measurments (Table 1, 2, 3, ), chemical analysis (Table 4), spectro chemical analysis (Table 5) and X-ray powder examinations are reported.