Unit of Length mentioned in WEI CHIN concerning Japanese People Critique of the short mileage theory

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Other Title
  • 魏志倭人伝の里程単位「一寸千(短)里」説批判

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Chou Pei Suan Ching (Shuh-hi-san-kei), which is an arithmetical classic of the gnomon and the circular paths of heaven, has put forward, in its first volume, a cosmological theory that heaven is circular and earth is square. The magnitude of the heaven and earth was measured by an 8 "shaku" gnomon and the distance to the terrestrial meridian was determined by the Pythagorean theorem from the results that the shadow length of the sun on the summer solstice was 1.6 "shaku" at "Chichuh" (Yohjoh in Kanan province) where was thought the center between heaven and earth, and 1.5 "shaku" and 1.7 "shaku" and at the place of 1000 "ri" to the exact south and north of "Chi-chuh" respectively. Although the above substance must be denied from the viewpoint of present scientific knowledge, there has been published an opinion that the above data are effectively evidential of the short mileage theory for the "Wei Chih Wo Jen Chuan" (Gishi-wajinden). Taking his stand on the result that the approximate value of 76~77m is obtained for the actual length of the unit of "ri" the formula of trigonometrical function on the basis of the sphericity of the earth and the above numerical values, he insists on that a unit of short "ri" mileage different from the common unit of approximatn 400~500m was used in those days. This paper denies the above short mileage theory by comparing the measurement errors of the shadew length of the sun and the distance in a straight line on the ground with various records in ancient China and then prooving that the numerical values recorded in "Shuh-hi-san-kei" are not actually measured values.

Journal

  • 計量史研究

    計量史研究 7 (1), 7-22, 1985-10-30

    日本計量史学会

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