Ino Tadataka Survey Location
Location:2 Okamoto,Ise City
Ino Tadataka (1745-1818), known for completing actual surveys of the whole land of Japan, visited current Ise City in May of 1805 during his fifth survey expedition. According to his survey records, Tadataka and his companions stayed for five days at Izumiya Hanzaemon’s Inn in the Oda area of Yamada(Yoda)-Okamoto Town, where they measured the moons of Jupiter (Galilean satellites) as they observed a celestial phenomenon called ryohan (eclipse and occultation).
Ryohan (eclipse and occultation) refers to a phenomenon that a satellite becomes obscured by a planet or its shadow. By accurately determining the local time in the two locations at which ryohan is observed (the time determined based on the meridian passing through those locations), the differences in time between two locations shows the differences in longitude between the two points. Tadataka observed the ryohan phenomenon at more than ten locations, mainly in western Japan.
According to his survey records, during their five-day stay, they visited Geku(the Outer Shrine) and stopped by the nearby Toyomiyazaki Bunko (Book Depository), where they perused the collection.
Later, Tadataka and his companions stayed for three days at Iwasaki Dayuu Residence in Uji where they took measurements of stars and went to Mt. Asamagatake to survey.
Even though Tadataka and his companions only stayed for eight days when they visited Ise, they were able to map the coastline of current Ise City precisely.
He visited Ise again on the way home from his sixth survey expedition, and while staying at Onshi (a low-ranking Shinto priest) Ryu Dayuu Residence for three days, he visited and prayed at both Geku and Naku (the Outer and Inner Shrines ) on the first day of 1808.
March 2018 Ise City Board of Education