The Use of Stone-Joint Metal Clamps to Bind

A Study of Stone-joint Metal Clamps in China and Korea during the 6th-8th Centuries* Hongnam Kim he use of stone-joint metal clamps to bind cut- to imply trans-regional circulation and world-wide stone blocks is a structural reinforcement de - adaptation of the technology. Time and again vTice in masonry construction. Popularly called world history proves that the speed of knowledge- “keystone cut clamps” in the Western world, their travel is much faster than local-level independent emergence seems to have coincided with the ad - inventions in the field of art and technology. vent of dry ashlar masonry, which required new 1 The Western world of the first millennium CE was, approaches in structural engineering. They signify it is no exaggeration to say, under the spell of a technical evolution in the manipulation of stones Roman technology and art in stone masonry—as in human history and bespeak the inseparable witnessed through Roman roads, aqueducts, am - unity of art and technology down to the last detail. phitheaters, victory gates, colosseums, and arch Stone-joint clamps have been found globally bridges built everywhere within the far reaches of stretching from South America all the way to the the Empire. Their stone monuments and architec - Far East, covering a long span of time [Fig. 1]. 2 By ture were virtually an encyclopedic repository of present knowledge, the earliest datable examples stone-joint clamps in all possible types and materi - come from Egyptian temples of the middle of the als. The enduring influence of the Romans even second millennium BCE in the shape of a flat rec - after the fall of Rome was felt strongly throughout tangular bar with curved-in waist, now commonly the Byzantine East and Sassanian Persia, who in referred to as a “dovetail” clamp. Clamp types vary turn were destined to be the transmitter of Roman in shape: dovetail, double-T (of “dumbbell-shape”) masonry to the Far East. sometimes with circular or semicircular heads, In East Asia, as of now, the earliest stone-joint straight bar, the alphabet capitals I and H, and clamps come from China and are datable to the butterfly (or “bow tie”). For the material, iron was early 6 th century CE, followed by Korea in the late the most popular, but wood, stone, bronze, lead, 7th century. Finds from India and Southeast Asia and even gold were used (modern retrofitting is date to the 9th-11th century, though some with done with steel or titanium). Due to their high even earlier dates may eventually surface. Admit - cost and the demand for skilled craftsmen to pro - tedly, a full investigation of the circumstances be - duce both the precision cut of clamp grooves and hind the relatively late arrival and sudden rust-proof metal clamps, these clamping devices flourishing of clamping technology in China and were mostly applied to architecture and monu - Korea is beyond the scope of this article. Such an ments built under state and religious commissions inquiry may lead us into the complex topic of con - of the ancient world. Despite their global presence tacts between East and West in the architectural and continuous reports on new findings, the sub - 3 field—an aspect that has been largely neglected in ject has not received serious scholarly attention. the general Silk Road narrative of transcontinental This is probably due to the fact that they are and transoceanic exchanges and encounters. mostly found lying buried and thus considered to be ancillary concern. But their common features in By its very nature, this “microstudy” on the subject form, material, production, and installation seem of stone-joint clamps cannot be conclusive, and ____________ * This is a revised and shortened version of an earlier article that was originally published in two parts. See Kim Hongnam, “Tongil-Silla jeongi Geonchuk ui Eun-jang Yeongu” [On stone-joint metal clamp “eun-jang” from early Unified Silla stone monuments], Misulsahak Yeongu , no. 303 (September 2019) and no. 304 (December 2019). A few more sites that came to my attention after publication necessitated some revision, but the main points of the argument remain unchanged. Copyright © 2020 Hongnam Kim The Silk Road 18 (2020): 81–108 81 Copyright © 2020 The Silk Road House Fig. 1. Examples of stone-joint clamps from around the world: 1) Upper Anubis shrine at the Temple of Hatshepsut, Egypt, Deir El-Bahari, c. 1450 BCE; 2) Theatre at the Acropolis, Greece, 5-4 th BCE; 3) Pasagarde, Iran c. 500 BCE; 4) Delphi Temple, Greece, 5 th -3 rd c. BCE; 5) Oikio Temple, Turkey, mid-4 th c. BCE; 6) Roman Forum, Rome, Mid-1 st c. BCE; 7) Pompeii, Italy, data - ble before 79 CE; 8) Aurelian Walls, Rome, 271–275 CE; 9) Artemis Temple, Sardis, Roman Section, 1 st -4 th c. CE; 10) Tigranakert Roman Ruines, Armenia. 1 st c. BCE; 11) Tunisia; 12) Axum, Ethiopia, 3 rd -5 th c. CE; 13) Puma Punku, Bolivia, pre-Inca; 14) Tiahua - naco, Bolivia, pre-Inca; 15) Tiahuanaco, Bolivia, pre-Inca; 16) Bijamandal Complex, India, pre-13 th c. CE; 17) My Son, Vietnam, ca. 10 th c. CE; 18) Ankor Wat, Cambodia, ca. 10 th c. CE; 19) Angkor Wat, Cambodia, ca. 10 th c. CE; 20) Borobudur Indonesia. ca. 9th c. CE; 21) Imperial Palace, Tokyo, Japan, ca. 17 th c. CE . new findings will lead to future revisions. But it is Stone-joint Metal Clamps from Northern worthwhile to take a step toward understanding China, 6th-7th Centuries CE the development of East Asian stone masonry. The The common Chinese term for stone-joint clamps primary aim of this paper is to introduce the Chi - is yaotie 腰鐵 (literally “waist-iron”), a term which nese and Korean stone-joint clamps of the period first appeared in early 8 th century literature to de - from the early 6 th century to the 8 th century scribe the dovetail-type clamps on the Zhaozhou through a few representative case studies. First is a Bridge of the Sui dynasty. According to current survey of the Chinese specimens, with particular knowledge, the earliest known yaotie clamps are 趙州橋 attention paid to the Zhaozhou Bridge of from the first three decades of the 6 th century dur - 隋朝 the Sui dynasty (581-618 CE), which repre - ing the Northern Wei dynasty 北魏朝 (386-534) in sents early Chinese stone architecture above the north and the Liang dynasty 梁朝 (502-557) in ground with a full-scale application of the device. the south. The second case study will be on Korean speci - mens found from sites in Gyeongju, the capital of The clamps found so far in the north are typologi - the Unified Silla dynasty 統一新羅 (676-935 CE). cally consistent with the “dovetail” type seen Special attention will be given to the Seokguram 石 throughout the Tang dynasty 唐朝 (618-906). But 窟庵 Buddhist grottoes of the mid-8th century, in the south a different typology emerges: the which features the true dome architecture of full- clamps are of the dumbbell type with heads in fledged ashlar masonry with sophisticated clamp - square or circular-shape, which belongs to the cat - ing technology. egory of T-shape in the West. Though limited to only two Southern Liang sites, one appears partic - 82 ularly significant in consideration of its imperial Nagahiro Hoshio are photographs of the grottoes connection with the Liang royal mausoleum in the with extensive damage, as if shaken by an earth - vicinity of its capital at Nanjing, the cultural center quake. All images of cave 19 are shown with repair of southern China. This typology, if practiced with work visible, and is especially prominent on the consistency, may indicate that the routes of its colossal seated Buddha. These photos of the statue transmission were different from that of the north; also reveal full-fledged yaotie, i.e., iron clamps of in fact, this would not have been impossible dur - dovetail type, to mend heavy cracks on the nose. ing the period of the Southern and Northern Dy - The application of three dovetail clamps is visible nasties 南北朝 (386-589), when China experienced on the damaged nose from the photographs [ Fig. political and cultural divisions between the non- 2]. 4 Obviously these photos were taken before final Chinese ruled states of the north and the Chinese- restoration work; at present, such traces of earlier ruled states of the south before reunification under repair work are no longer visible. th the Sui dynasty at the end of the 6 century. Since the dovetail-type clamps persisted through the Tang dynasty in northern China, the applica - A Seated Colossal Buddha, Yungang Grottoes tion of clamps and the occurrence of damage must Stone-joint clamps were found in a curious cir - predate Song dynasty. The only pre-Song natural cumstance in cave 19 of the Yungang Grottoes 雲岡 disaster which could have affected the Yungang 石窟 at Datong 大同 in Shanxi 山西 province. Es - grottoes to such an extent was the great Shanxi tablished under the patronage of the Northern Wei earthquake in the year 512 (two later Shanxi earth - court, the grottoes were carved directly into the quakes in 1303 and 1556 are thus not applicable). face of a cliff. The seated colossal Buddha in the The 512 earthquake, which was of 7.5 magnitude, cave is one of the five colossal Buddha statues exe - shook northern Shanxi, including the Datong area, cuted in the first period (460-465) of the Yungang and took lives of more than 5,300 people. Consid - project as representations of five early Northern ering their symbolic importance to the Northern Wei rulers as reincarnations of the Buddha.

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