Yanagi Narayoshi - Yanagi Narayoshi

Mathematician of the Meiji period. Organizer of the Navy's hydrographic project. Born in the domain's residence in Yanagiwara, Edo, as the son of a samurai of the Tsu domain in Ise (present-day Mie prefecture). His pen name was Hotaro, and he was commonly known as Sogoro. He studied Japanese mathematics under Murata Tsunemitsu (?-1870) of the same domain, and in 1850 (Kaei 3) co-authored Shin Kosanpo (New Calculation Method) with his teacher. He was sent to the Nagasaki Naval Training School by domain order, where he learned surveying and navigation techniques based on Western mathematics, and after returning to the domain, he surveyed Ise Bay. In 1869 (Meiji 2), in response to a British warship attempting to survey the coast of the inland sea, he was appointed by the government, which planned to conduct a survey on its own, and began hydrographic surveying. He rose to the ranks of Lieutenant Commander of the Hydrographic Bureau in 1871, Navy Colonel and Chief of Hydrographic Affairs in 1875, and Rear Admiral and Director of the Hydrographic Bureau in 1880, and consistently worked to improve the Hydrographic Journal. He became a member of the House of Peers in 1888 and a member of the House of Peers in 1890. On the other hand, he founded the Tokyo Mathematical Company together with Kanda Takahira in 1877 as a representative, bringing together Japanese and Western mathematics experts, but around the time of the reorganization into the Tokyo Mathematical and Physics Society in 1884, Yanagi and other naval-affiliated and Japanese mathematics faction members withdrew from the company. During his time as a member, Yanagi attempted to explain Japanese mathematics using Western mathematics. His books include "Kaikoku Suiroshi" and "Umino Sutenawa".

[Hiroshi Ishiyama]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

明治期の数学者。海軍水路事業の組織者。伊勢(いせ)（現、三重県）津藩士の子として江戸柳原の藩邸に生まれる。字(あざな)は芳太郎、通称総五郎。同藩村田恒光(むらたつねみつ)（？―1870）に和算を学び、1850年（嘉永3）『新巧算法』を師と分担して著す。藩命により長崎海軍伝習所に派遣され、洋算に基づく測量・航海術を習得し、帰藩後、伊勢湾を測量した。1869年（明治2）イギリス軍艦が内海沿岸測量をしようとするのに対し、自力測量を計画した政府に起用され、水路測量に着手。1871年水路局少佐、1875年海軍大佐・水路権頭(ごんのかみ)、1880年海軍少将・水路局長に進み、一貫して水路誌の整備に努めた。1888年元老院議官、1890年貴族院議員となった。他方、1877年神田孝平(たかひら)とともに総代となって東京数学会社をおこし、和算・洋算家が結集したが、1884年東京数学物理学会への改組前後に、柳ら海軍系や和算派は脱退した。在会中、柳は和算の洋算による解説を試みている。著書に『海国水路志』『海人の捨縄』等がある。

［石山　洋］

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