1) In March, 1809, when Inô returned to Edo from the survey of Shikoku, he was requested by TAKAHASHI Kageyasu a 'young astronomer of the Astronomical Bureau, a son of the late TAKAHASHI Yoshitoki and the supervisor of the completion of Inô's Maps, to help him to compile a provisional map of Japan as one of the basic materials for the regional geographical survey of Japan, which was being undertaken by the Tokugawa Government. TAKAHASHI and INÔ compiled it in haste at the scale of 1 : 864, 000 and presented it in August to the Government with the Introduction of TAKAHASHI on its margin (Fig. 1). The provisional map included the main part of Japan on one sheet ; Hakodate and its vicinity on the north-east and Tanegashima and Yakushima on the south-west corner, with the prime meridian passing through Kyôto. The coastline and a few roads were drawn according to INÔ's survey, the courses of rivers and the boundaries of provinces were drawn with reference to various kinds of old provincial maps. The most difficult part of the work was making the map of Kyûshû, because INÔ's actual survey was not yet extended to Kyûshû. So they compiled the map of it from various materials, particularly referring to the map of Japan compiled by NAGAKUBO Sekisui (1717-1801), as was stated in the TAKAHASHI'S Introduction. But the result was seemingly far from being successful ; the shape of the main island of Kyûshiû was narrower in the east-west and longer in the north-south distances than the actual. Many discussions have been made among modern cartographers concerning the reasons for the peculiar shape of the island of Kyûshû. Some attributed it to the too much confidence of TAKAHASHI and INÔ on the description of one of astronomers in 1698, in which the latitudes of several towns of Japan were listed and Kagoshima was indicated as 31°N ; others made an effective argument against it because TAKAHASHI was informed of a fairly accurate latitude of Kagoshima and he was not a stickler for such an unreliable description. In consequence, the problem has remained unsolved until today. 2) The author analysed to the map carefully and appreciated TAKAHASHI'S diplomatic ability and solicitude behind it to carry out In7ocirc;'s survey successfully and effectively. This appreciation was assumed, though definite documents which directly prove my appreciation were lost, from two points concerning the map which deserve special attention. Firstly, the map of Kyûshû was greatly different in its character and content from that of other districts which were drawn according to INÔ's survey. The former was drawn in detail with many place names even in the interior part of the land as well as along the coast (Fig. 4). While in other districts, the names of important towns along INÔ's surveyed routes were almost neglected and the emphasis was laid upon the names of small islands, rivers, provinces, semi-provinces and boundaries of provinces ; on the whole, the map was drawn in outline (Fig. 2). This difference in characters between the map of Kyûshû and that of other districts was reversal of the case in the ordinary sense of map. drawing. This attempt must have been born of TAKAHASHI'S resource to persuade the Government the importance of detailed survey of the inland part of the land, without ending INÔ's work by mere coast survey. It was successful and after the map was presented to the Government, INÔ's project was greatly expanded and many roads of the inland part of Kytisha and of ChOgoku districts were surveyed. The island roads survey was extended even to the districts of Kinki and of Central Japan.
The writer summarized the recent progress of conodont research by himself and his collaborators. Conodonts have been found out from the Silurian, Carboniferous, Permian and Triassic sediments in various localities of the Japanese Islands. Most of these discoveries contribute new evidences for geochronology, biostratigraphy, geotectonics and geologic evolution of the Japanese Islands.
On the occasion of the heavy snow fall in January, 1963 in Hokuriku district the Geographical Survey Institute started its snow surveys by aerial photographs on a scale of 1 : 20, 000. Snow depth was measured at snow fissures on the slopes or exposed snow sections near the water on the photographs, using Stereotope, the third order instrument. At the same time the data on snow depth were collected at the observatories in the area. On the basis of these materials and stereoscopic photointerpretation the snow depth map 1 : 200, 000 was compiled, on which the isodepth lines of snow cover were illustrated at one meter interval. Distribution of snow avalanches as well as the prevailing wind direction on the ground were also analyzed by stereoscopic photointerpretation. After this, maps of the same kind, but more improved, were compiled for many areas. In this paper, referring the snow surveys along the planning routes of Tokai-Hokuriku, Chugoku-Odan and Tohoku-Odan Expressways, the method of show depth measurement, classification of mountain slopes for predicting the occurrence of snow avalanches and the method for estimating the force of snow avalanches are explained. To measure the snow depth on aerial photographs, the so-called relative height method is mainly used, that is to measure the relative height of snow surface from the ground using facilities such as airphoto signals for snow season. At the same time as indirect method the comparison of exposure of roads, railways as well as houseroofs in the snow and non snow seasons were also introduced. The deepest snow depth in the past was estimated from the photographing date by correlation analysis. The main results obtained are the classification of mountain slopes based on the occurrence ratio of snow avalanches and results of field surveys (Table 5), the map of snow depth and snow avalanches distribution (Fig. 11), and of the danger-degree distribution of snow avalanches (Fig. 12).
It is a very urgent subject for our country to survey physical process of rocky mudflow which has been causing serious damages in mountainous regions every year. There seems to be various methods to approach the essential phenomena of rocky mudflow, and field survey after the occurrence of mudflow or experimental study of mudflow has been comparatively well undergone as an effective method. But a direct observation has been hardly planned on moving process of actual mudflow because of the danger of observer and difficulty of recording. Considering above situation, in order to carry out a systematic and exact observation on moving state of rocky mudflow, a new synthetic observation system has been developed by Mudflow Research Group. This observation system consists of velocity sensors connected with time recorder for the measurement of local variation of front velocity and 8 mm cine cameras, 16 mm cine camera, videocamera, a pair of stereo cameras to analyze the dynamic movement of mudflow front, and strain gauge to record the impact force of mudflow. All these instruments are ready for automatic recording. In addition to above system, rain gauges and mud samplers were set in the same observation area to study occurrence condition and physical property of flowing substance. After the preliminary test in 1970, a field test of whole system was carried out in 1971 at Valley Kamihori on eastern slope of Mt. Yake, North Japan Alps, Nagano Prefecture. In the morning on 6 th Sept. 1971, our new system succeeded in recording the motion of rocky mudflow several times, and valuable information about it was got from this record in relation to hydrological and microtopographical conditions. A general explanation on the observation in 1971 are described in this paper, accompanied with some reviews of present state of mudflow research.