An historical monument was found in Abashiri, northeastern Hokkaido. The monument curved with the letter “Tensokuten ” has turned out the astronomical survey marker placed by Hokkaido prefectural survey office in 1889. Land survey in Hokkaido by trigonometrical method was carried out from 1873 conducted by a few U.S. surveyors, however triangulation network based on the geodetic datum origin in Tokyo has not expanded to Hokkaido until early 1900’s. Therefore Hokkaido prefectural survey office set up the geodetic coordinate independently on astronomical observation. One of the characteristics is that this marker has leveling survey cut-benchmark introduced from Great Britain by Japanese Ministry of Interior early 1870’s which shows remarkable case in Hokkaido. The authors would expect this marker to be conserved as the historical monument of the survey in Hokkaido.
