総説・展望
伊能図の科学技術的側面と分類体系に関する先学の業績と今後の課題
2021 年 59 巻 4 号 p. 1-15
詳細
2021 年 59 巻 4 号 p. 1-15
Inoh’s map is the first scientifically surveyed map of Japan. Inoh Tadataka (1745-1818) started his nationwide survey over ten times from 1800 and the maps of his results were compiled and submitted to Tokugawa Shogunate Government in 1821 three years after his death.
His motive of the nationwide survey was to get the latitude distance. He drew the map of Japan based on the latitude distance obtained by his survey. His method of survey was traversing, intersection and astronomical observing. We can know his method briefly from the explanation record left by Watanabe Shin who was one of his best pupils. Afterward Ohtani Ryokichi wrote the voluminous work in 1917 about Inoh’s achievements based on Watanabe’s record, Inoh’s maps and his existent survey instruments, and Hoyanagi Mutsumi compiled famous work in 1974 about the scientific technology of Inoh’s survey and mapping.
These two classical studies on Inoh’s achievements, namely INOH TADATAKA written by Ohtani Ryokichi and A NEW APPRECIATION OF THE SCIENTIFIC ACHIEVEMENT OF INÔ-TADATAKA WHO ESTABLISHED A LANDMARK IN THE HISTORY OF LANDSURVEY AND CARTOGRAPHY OF JAPAN edited by Hoyanagi Mutsumi, have variously influenced and been commonly accepted on the studies of Inoh’s survey and maps since then,
Although Inoh’s original maps submitted to Tokugawa Shogunate Government were burnt out in 1873, some duplicates are existing still now. Taking the opportunity of two hundred years anniversary from the commencement of Inoh’s survey, some new Inoh’s maps were found out and bibliographical studies on Inoh’s maps have much progressed. However, scientific cartographical studies have not so much progressed yet.
As for the scientific cartographical themes, the four subjects such as 1) Latitude distance, 2) Inoh’s survey method, 3) Map projection and 4) Mapping process are discussed. Concerning these subjects, the author introduces the commonly accepted views, which are based on the two classical studies of Ohtani and Hoyanagi, and introduces newly reconsidered theories by Nogami Michio. Nogami denied the commonly accepted views and emphasized that the numerical value of latitude by astronomical observing is most fundamental survey framework and traversing corresponds to the detail mapping. The author evaluates his new theories.
Inoh’s maps are divided to “The large-scale map (“Daizu” 1:36000)”, “The medium- scale map (“Chuuzu” 1:216000)” and “The small-scale map (“Shouzu” 1:432000)”. According to Inoh’s mapping process, a draft map (“Shitazu”) is plotted from his survey data for every one day surveyed area at first. Every “Shitazu” is connected each other to one sheet of “Daizu” and the manuscript maps are prepared. He reproduced Inoh’s maps from these manuscript maps by using needle plotting method. Therefore, we can recognize existing of needle plot hole of surveying data on Inoh’s maps prepared by Inoh Tadataka and his group.
The existent Inoh’s maps are divided to complete maps prepared after the complete of his nationwide survey and intermediate maps prepared after every stage of his survey. Furthermore, besides Inoh’s maps prepared by him and his group themselves, various duplicate maps have been prepared until present time. Duplicate maps vary from faithfully copied to transformed. Especially, Japanese Army, Navy and Ministry of Interior copied Inoh’s maps in the early Meiji period. These copied maps were used for preparing the modern Japanese National Maps.
