高橋景保・伊能忠敬編「日本輿地図藁」考

抄録

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.