1660年以後の和算書その他における金属と水の密度の値 : その停滞と退歩

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After the preceding paper "On the Densities of Metals and Water in the Early Books of Mathematics in Japan-The Ones carried and improved-", the authors continued to study how the value of densities (of metals and water) had been succeeded, by the Japanese (mathematicians, scholars and merchants) in the Edo period, whether that had actually been measured by them or not, and how the idea of density of substance had been considered at that time. As seen in the preceding paper, down to 1660's, the Japanese books of mathematics had been giving a variety of densities of metals and water, and correcting the values little by even with discussions based on those mathematicians' own meaurements. In the years from 1660 onward to the end of the Tokugawa regime, however, the Japanese books of mathematics were revealed to have discontiuned efforts at improving the values of density : many of these books only quoted various values of density from the authoritative Jinkoki and other books of mathematics, but the authors of these books did not make efforts to correct the values into the precise ones. Furthermore, as the values of density differed largely depending on the books, it was emphasized that the density of a certain substance differs according to time and place, and consequently even the truth that the density of pure substance is definite came to be disregarded by those authors. In 1660's the density of water settled down 0.99 to 1.01g/cm^3 (at the conversion of c. g. s. unit), but in 1790's the absurd value of 0.88 g/cm^3 even emerged. In the 19 th century Japanese scholars had first an opportunity of consulting the density tables of European origin. Though the European method of measuring density at that time was based on the Archimedean principle, and was far more precise than the methods up to that time in Japan, N. Kurihara expressed disapproval of accepting the European values as they were by the reason that the density of water was not always fixed (in 1848). It may be said that, from 1660's on to the end of the Edo priod, the density tables in Japanese books of mathematics retrogressed rather than were retarded.
日本科学史学会の論文
1981-07-31

1660年以後の和算書その他における金属と水の密度の値 : その停滞と退歩

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