01 / Telescope
With a telescope he built himself,he watched sunspots for over a year.

Born into a family of Kunitomo gunsmiths, Ikkansai began building a reflecting telescope in 1832 (Tenpo 3). From the 6th day of the first month of Tenpo 6 (1835) to 8 February the next year, he observed sunspots twice a day whenever the sun was visible. The 953 items of the Kunitomo Ikkansai-related materials became an Important Cultural Property in 2023.
- Telescope work began, 1832
- Sunspots observed twice a day
- Important Cultural Property, 2023


