Genkei Nakane

Japanese: 中根元圭 - なかね・げんけい

Year of death: September 2, 1733 (October 9, 1733)
Year of birth: 1662
He was one of the most outstanding scholars of astronomy and calendars, far surpassing his contemporaries in the Edo Shogunate Astronomical Bureau, and a master of Japanese mathematics. His given name was Sho and he was called Jouemon. He was born in Asai-gun, Omi Province (Shiga Prefecture), as the son of a doctor, and later lived in Hakusan, Kyoto, where he was called Hakusan Sensei. When he was working as an official in Kyoto's Ginza district, Astronomical Bureau, Toyojiro Ikai, was unable to answer questions from Shogun Tokugawa Yoshimune, he was recommended by Yoshimune's academic advisor, Takebe Katahiro, to respond to Yoshimune's questions regarding the quality of the Jokyo calendar. He also told Yoshimune that at the time, even excellent Western academic books on natural sciences were banned and could not be imported if they contained even the slightest reference to Christianity, which hindered the progress of learning, and he recommended that the ban be relaxed, and it can be said that Genkei's great achievement was that he made this happen. He was ordered to translate the "Rekisan Zensho" (Complete Book of Calculations) that had been imported from China, and completed the translation. He also went to Shimoda, Izu, by order of Emperor Yoshimune to observe the sun and moon and investigate the differences in the Jokyo calendar. His work, "Kowa Tsureki" (Kowa calendar), became the basis for "Sansho Soran" (Sansho Comprehensive Calculations), which was used for a long time as a long-running calendar after the Meiji period. He also wrote many books, including "Sansho Zokukai" and "Shoujireki Zukai Kaihou", and in mathematics he was said to be the most skilled disciple of Takebe Katahiro.

(Masao Uchida)

Source: Asahi Japanese Historical Biography: Asahi Shimbun Publications Inc. About Asahi Japanese Historical Biography

Japanese:

没年：享保18.9.2(1733.10.9)
生年：寛文2(1662)
同時代の江戸幕府天文方をはるかにしのぐ,優れた天文暦学者のひとりで和算の大家。名は璋で丈右衛門と称した。近江国(滋賀県)浅井郡に医者の子として生まれ,のち京都の白山に住んだので白山先生と呼ばれた。京都銀座の役人をしていたころ,天文方猪飼豊次郎が将軍徳川吉宗の質疑に答えられなかったとき,吉宗の学問の顧問建部賢弘に推挙され貞享暦の精粗につき吉宗の下問に応答した。また吉宗に対し,当時は優れた西欧の自然科学の学術書でもキリスト教に少しでも触れた個所があると,禁書となって輸入できず,そのため学問の進歩が妨げられることを述べ,禁令をゆるめるよう進言し,それが実現したことは元圭の大きな功績といえよう。清国からかくて輸入された『暦算全書』の翻訳を命ぜられそれを完成し,また吉宗の命で伊豆下田に赴き太陽・月の観測を行い貞享暦の差異を調べた。その著『皇和通暦』は明治以後長暦として長く使われた『三正綜覧』のもとになった。『三正俗解』『授時暦図解発揮』その他著書は多く,数学では建部賢弘の第一の高弟といわれた。

(内田正男)

出典　朝日日本歴史人物事典：（株）朝日新聞出版朝日日本歴史人物事典について　情報

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