Forma, Vol. 16 (No. 3), pp. 177-186, 2001
Original Paper

Parabola Drawing Methods in Traditional Japanese Architecture —A Hypothesis in Technological Genealogy

Hiroshi Yanai

Department of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan

(Received September 3, 2001; Accepted October 12, 2001)

Keywords: Jacket Walls of Japanese Castles, Gotoh's Manuscripts, Ying zao fang shi, Drawing Procedures, Mathematical Formulae of Architectural Curves, Parabola

Abstract. A drawing procedure of the curves of stone jacket walls in Japanese castles is described in manuscripts of Gotoh family written in early 17th century. This procedure is based on constructing a parabola with horizontal axis as an envelope of a set of straight lines made by spanned strings. The origin of such a procedure is surmised to be in "Ying zao fang shi" published in 1078 in China in which an envelope is used to construct the curve of the wooden support between pillar and beam. The validity of this conjecture is to be discussed in this paper.

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