中根元圭に伝えられた田中由真の測量術と測器具“カロト”について

概要

Nakane Genkei (1662-1733) who lived in the old capital Kyoto studied mathematics under Tanaka Yoshizane (1651-1719). It is not clear when Nakane became Tanaka's pupil, but by 1691 (fourth year of the Genroku period) he had matured to the extent that he published the Shichijōbeki enshiki. It is thought that Nakane Genkei was also an expert in the surveying, but the actual state of his knowledge is not well known. However, it is certain that he was also taught the surveying techniques by his teacher in arithmetic studies, Tanaka Yoshizane. The manuscript entitled the Sokuen-jutsu exists in the Hirayama Bunko collections of the Tōhoku University Library, which describes surveying techniques was introduced by Y.Tanaka to G. Nakane. In this paper we introduce the surveying technique in the Sokuen-jutsu of Y. Tanaka and discuss the usage and meaning of the measuring instrument “karoto” that appears in this book.