Wood cutting - Kiwari

A method of determining the dimensions of each building component and their combinations by proportion. Although it varies depending on the size of the building, generally the center space between the columns at the front is used as the standard, and the thickness of the columns is determined by one-tenth or one-twelfth of that. The dimensions of the nageshi (rail-like support beams), nuki (struts), rafters, and taruki (rafters) are determined by a certain percentage of the thickness of the columns. In addition, the dimensions of the columns are determined by determining how many rafters are to be placed between the columns, and details such as the six-strut support beams, which determine the size of the structure with six rafters, are also determined. Wood splitting has been an empirical method used by craftsmen since ancient times, and even the Golden Hall of Horyuji Temple had certain standards for the cross members such as rafters and elbows. In the Nara period, efforts were made to produce standard lumber by setting the cross sections to 5, 6, 7, and 8 sun, and 5 sun (15 cm), 6 sun (18 cm), 7 sun (21 cm), and 8 sun (24 cm). Craftsmen would pass on the secrets of how to use such sized timber, and would also examine and copy buildings to determine their structure and then construct them.

The oldest architectural drawings are the two volumes of the "Shina Zen Temple Diagrams" (Shinzen-Satsu Zushiki), which were imported from China in the late 13th century and are housed at Daijoji Temple in Kanazawa City, Ishikawa Prefecture, and show detailed illustrations of Zen Buddhist architecture. The proportions of each component were specified in detail from the late Muromachi period, and the "Gusikenki" (Gushikenki), which was passed down to the craftsmen of Horyuji Temple, records the existence of the "Sandaimaki" (Sandaimaki) with a colophon dated 1489. The contents of the "Sandaimaki" were simple, but the "Shomei" (Shomei) created in 1608 (Keicho 13) specifies the wood divisions in detail for various buildings, including shrines, temples, and houses. In the Edo period, various wood division books were published, and well-known examples include the "Buke Hinagata" (Buke Hinagata), "Sukiya Kohoshu" (Collection of Sukiya Construction Methods), and "Daiku Kiku Shakushu". Just as in architecture, timber was used in the design of Japanese ships, with the size of each component being determined by the kiwari (wood splitting) system, which was based on the length of the ship's bottom (kawara) of 1 hiro (approximately 1.8 meters), the yagake (ro) system, which was based on the oar, and the hogarika (sail splitting) system, which was based on 1 tan (sail).

[Kudou Yoshiaki]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

建物の各部材の寸法やその組合せを比例によって定める方式。建物の規模によって違いがあるが、一般に正面で柱間がもっとも広い中央間を基準とし、その10分の1ないし12分の1を柱の太さに決め、この柱の太さの何割かで長押(なげし)、貫(ぬき)、桁(けた)、垂木(たるき)などの寸法を決める。また、垂木を何本柱間に配するか支割を決めて柱間寸法を考え、垂木6本分で組物の大きさを決める六支掛など、細部も定める。木割は古くから工匠がもっていた経験的手法であり、法隆寺金堂でも桁、肘木(ひじき)などの横材には一定の規格があった。奈良時代においては、木材を製材するのに5、6寸、7、8寸とか、断面を5寸（15センチメートル）と6寸（18センチメートル）、7寸（21センチメートル）と8寸（24センチメートル）と決めて規格材の製産に努めている。このような規格材をどのように使うかを工匠は相伝し、また、建物を実査模倣して構成を定め、建物を建てていた。

　建築図として古いものは石川県金沢市・大乗寺所蔵の13世紀末に中国から将来した『支那禅刹(しなぜんさつ)図式』2巻があり、禅宗様の細部などが図示されている。各部材の比例が細かく定められたのは室町時代後期ころからで、法隆寺の工匠に伝えられた『愚子見記』に、長享(ちょうきょう)3年（1489）の奥書のある『三代巻』があったことが記されている。『三代巻』の内容は簡単なものであったが、1608年（慶長13）につくられた『匠明(しょうめい)』は社寺、住宅など各種建物まで、綿密に木割を定めている。江戸時代になると木割書が種々刊行されるようになり、『武家雛形(ひながた)』『数寄屋(すきや)工法集』『大工規矩(きく)尺集』などが知られている。建築と同じように和船の設計にあたっても木割が用いられ、船底の長さの(かわら)1尋(ひろ)（約1.8メートル）を基準とする尋掛り、櫓(ろ)を基準とする櫓掛り、帆1反を基準とする帆掛りがあり、それぞれ部材の大きさを決定した。

［工藤圭章］

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