Japan's first reflecting telescope, made in 1834, is as efficient as those currently being manufactured for amateur astronomers, according to a group of Kyoto University researchers.
The reflecting telescope was made by Kunitomo Tobei (1778 -- 1840), a gunsmith in Nagahama, Shiga Prefecture, and is kept at the Ueda Municipal Museum in Shiga Prefecture. It is 42 cm long, has a 6.2 cm aperture and is the first of four existing telescopes made by Kunitomo.
Yoshio Tomita, an assistant at Kyoto University's Faculty of Science, found that the bronze reflecting mirror in the barrel was almost as bright as a brand new one. With the approval of the Ueda Municipal Government, Tomita and 11 others in his group disassembled the telescope for close scientific examination, which began in July 1997.
The team found that the mirror is an alloy of copper and zinc, which is difficult to oxidize, and that its reflectance is almost as strong as when it was produced. The meniscus of its primary mirror is so precise that it compares favorably with present-day products, according to Tomita.