Inō was born in Kujūkuri, a coastal village in Kazusa Province, in what is now Chiba Prefecture, and was adopted (aged seventeen) by the prosperous Inō family of Sawara (now a district of Katori, Chiba), a town in Shimōsa Province. He ran the family business, expanding its sake brewing and rice-trading concerns, until he retired at the age of 49. At this time he moved to Edo and became a pupil of astronomer Takahashi Yoshitoki, from whom he learned Western astronomy, geography, and mathematics.
In 1800, after nearly five years of study, the Shogunate permitted Inō to perform a survey of the country using his own money. This task, which consumed the remaining seventeen years of his life, covered the entire coastline and some of the interior of each of the Japanese home islands. During this period Inō reportedly spent 3,736 days making measurements (and travelled 34,913 kilometres), stopping regularly to present the Shogun with maps reflecting his survey's progress. He produced a number of detailed maps (some at a scale of 1:36,000, others at 1:216,000) of select parts of Japan, mostly in Kyūshū and Hokkaidō.
Inō's magnum opus, his 1:216,000 map of the entire coastline of Japan, remained unfinished at his death in 1818, but was completed by his surveying team in 1821. An atlas collecting all of his survey work, entitled Dai Nihon Enkai Yochi Zenzu (ja:大日本沿海輿地全図 Maps of Japan's Coastal Area), was published that year. It had three pages of large scale maps at 1:432,000, showed the entire country on eight pages at 1:216,000 and 214 pages of select coastal areas in fine detail at 1:36,000. The Inō-zu (Inō's maps), many of which are accurate to 1/1000 of a degree, remained the definitive maps of Japan for nearly a century, and maps based on his work were in use as late as 1924.
In addition to his maps, Inō produced several scholarly works on surveying and mathematics, including Chikyū sokuenjutsu mondō and Kyūkatsuen hassenhō.
Inō is celebrated as one of the architects of modern Japan. A museum, dedicated to his memory, was opened in his former home in Sawara, and in 1996 was designated a National Historic Site. In November 1995 the Japanese government issued a commemorative 80 Yen postage stamp, showing Inō's portrait and a section of his map of Edo. Most of the complete copies of the atlas have been lost or destroyed (often by fire), although a mostly-complete copy of the large-scale map was discovered in the collection of the U.S. Library of Congress in 2001.
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- Ogawa, Florence. (1997). "Ino Tadataka, les premiers pas de la geographie moderne au Japon," Ebisu, Vol. 16, pp. 95–119.