It is the one of noteworthy things to see in the narrow mountanious island country like Japan, how and to what extent the high and gradient lands are actually cultivated. And this kind of investigation has been done hitherto largely in the central mountanious district and in the skirt of various volcanoes. As a result, apart from the mutual relation between the farming land and its height in which the latitude of the place plays a large part, it has been reported, in the case of gradient land, that the gradient of the land suitable for cultivation should be smaller than 15°. And the same kind of investigation was applied to that of the Island of Awaji, one of the islands in Inland Sea (Setonaikai) where the cultivation of gradient lands is highly developed. It has been proved that the greater part of the Island of the Island of Awaji which has the gradient of 20° or more and is used as paddy fields or orchards, as expected before the investigation, exceeds the average gradientof 15°. Of course, most paddy fields or orchards have the gradient of 10_??_15° or of less than that. Therefore, the limit of the gradient in the farming land of the islands in the Inland Sea where almost all islands are cultivated to their sum mits, has an eminent difference compared with that of the United States, little difference compared with the average limit of the gradient in our country. There was little difference between the limits of the gradient in the farming land and that of urban dwelling area in the city of Ashiya. In short, the limit of the gradient both in farming lands and dwelling areas in the steeply sloping cities is to be under 15° in our country.

抄録全体を表示