kaerumata 蟇股
KEY WORD : architecture / general terms
Frog-leg strut. A strut with legs spread like those of a frog. Kaerumata in the early Nara period developed from an inverted warizuka 割束 shaped strut to a very thick strut rounded on each end with an onion-shape carved halfway through, horishizume 彫沈. Frog-leg struts are usually positioned between parallel purlins *keta 桁 in the space between the bracket systems *tokyou 斗きょう that are atop each pillar. Frog-leg struts are also used to support transverse rainbow beams *kouryou 虹梁 that stretch across the core *moya 母屋 of a temple building or across the smaller transverse beams of the aisles *hisashi 廂. They are also frequently found in gable ends. The oldest frog-leg struts were shaped from single thick boards with no open spaces and were used to carry large bearing blocks and bracket arms *daito hijiki 大斗肘木 that in turn supported heavy beams *nuki 貫. This type of frog-leg strut is called itakaerumata 板蟇股. These solid board frog-leg struts were completely functional. The struts placed between two rainbow beams were wider than they were high. However, those positioned on beams to support the ridge were higher than their width. The use of solid-board frog-leg struts did not die out even though they were used less frequently from the Heian period through to the 13c. From the 10 - 11c, kaerumata began to have some open areas, and the timber used became thinner. Those with open spaces are called either honkaerumata 本蟇股 or *kurinuki kaerumata 刳抜蟇股. One method to shape the frog-leg strut was to use a single piece of wood and then cut openings to make a design. This is called *sukashikaerumata 透蟇股. The shape of the openwork gradually changed. The legs became shorter, stretched out further, and the feet were elongated. Carvings gradually became more ornate in the latter Heian period and continued through the latter Kamakura period when intricate arabesques and even *houju 宝珠 (treasure jewels) were included within the frame of the frog-legs. The inside decoration of frog-leg struts in the Nanbokuchou and the Muromachi periods became much more decorative and filled the entire space. Houju, lotus, arabesques, flame patterns peonies, paulownia, birds and clouds embellished the once simple frog-leg frame. During the Momoyama and Edo periods the carvings within the frog's legs are often elaborate and many are brilliantly colored. Proportions of legs and feet changed and the bearing block on top of the frog-leg strut is often undersize. Some excellent work of sculpture filling the area between the frog-legs continued through most of the 17c. The left and right pieces were carved out in reverse directions so that when combined a triangular shaped frog-leg strut was produced. This method was called the *gasshou 合掌 style. The upper part was curved to create a place for the insertion of the base of a bearing block *masu 斗. It is presumed from the paucity of examples that this technique never became popular. For a relatively short time a different process was devised to create decorative frog-leg struts: The strut was shaped and then cut in half vertically.
Houryuuji Kondou 法隆寺金堂 (Nara)
a) warizuka 割束
Houryuuji Kondou 法隆寺金堂 (Nara)
     Houryuuji Higashimon 法隆寺東門 (Nara)
Houryuuji Higashimon 法隆寺東門 (Nara)
Toudaiji Tengaimon 東大寺転害門 (Nara)
Toudaiji Tegaimon 東大寺転害門 (Nara)
  Turugaoka hachimanguu Roumon  鶴岡八幡宮楼門 (Kanagawa)
Tsurugaoka hachimanguu Roumon
鶴岡八幡宮楼門 (Kanagawa)

*nijuukouryou kaerumata 二重虹梁蟇股

(C)2001 Japanese Architecture and Art Net Users System. No reproduction or republication without written permission.