Die Chinesischen Zauberspiegel (透光鏡 bzw. tòu guāng jìng) lassen sich mindestens bis ins 5. Jahrhundert zurückverfolgen, obwohl behauptet wird, dass sie bereits während der Han-Dynastie (206 v. Chr. - 24 n. Chr.) existierten. Die Spiegel waren aus massiver Bronze gefertigt, deren Vorderseite glatt poliert war und so als Spiegel verwendet werden konnte. Gleichzeitig wies die Rückseite ein in die Bronze gegossenes Ornament auf. Wenn Sonnenlicht auf einen solchen Spiegel fällt, scheint er durchsichtig zu werden und wenn das Licht vom Spiegel auf eine Wand reflektiert wird, wird dort das Muster auf der Rückseite des Spiegels projiziert.[2]
Die Rückseite des Bronzespiegels waren in vielen eurasischen Kulturen der Standard, aber den meisten fehlte diese besondere Eigenschaft, weshalb die reflektierenden Spiegel auch als Zauberspiegel bezeichnet wurden. [3]
Aufbau
BearbeitenDie Spiegel wurden hergestellt, indem man geschmolzene Bronze in eine Form goss, die mit dem reliefartigen Ornament versehen war. Der erstarrte Rohling wurde anschließend auf einer hölzernen Unterlage mit einer Art Hobel bearbeitet, um die Oberfläche zu glätten. An den Stellen, an denen sich die Vertiefungen des rückwärtigen Reliefs befinden, trägt der Hobel weniger ab als an den auf der Unterlage aufliegenden erhabenen Stellen des Reliefs, sodass sich die Oberfläche an den entsprechenden Stellen geringfügig aufwölbt, sobald die durch den Druck bedingte Durchbiegung nachlässt. Wenn Licht auf diese durch Vertiefungen und Erhöhungen leicht gewellte Oberfläche fällt, wirken die Vertiefungen wie kleine Hohlspiegel, die das Licht ihrem Krümmungsradius entsprechend fokussieren, während die Erhöhungen zu einer Defokussierung führen. Infolgedessen ist im reflektierten Licht eine leichte Helligkeitsmodulation erkennbar, die in ihrer Struktur den Vertiefungen und Erhöhungen und damit der sie verursachenden Form des Reliefs entsprechen. [4]
The basic mirror shape, with the design on the back, was cast flat, and the convexity of the surface produced afterwards by elaborate scraping and scratching. The surface was then polished to become shiny. The stresses set up by these processes caused the thinner parts of the surface to bulge outwards and become more convex than the thicker portions. Finally, a mercury amalgam was laid over the surface; this created further stresses and preferential buckling. The result was that imperfections of the mirror surface matched the patterns on the back, although they were too minute to be seen by the eye. But when the mirror reflected bright sunlight against a wall, with the resultant magnification of the whole image, the effect was to reproduce the patterns as if they were passing through the solid bronze by way of light beams.[5][6]
Geschichte
BearbeitenIn about 800 AD, during the Tang dynasty (618–907), a book entitled Record of Ancient Mirrors described the method of crafting solid bronze mirrors with decorations, written characters, or patterns on the reverse side that could cast these in a reflection on a nearby surface as light struck the front, polished side of the mirror; due to this seemingly transparent effect, they were called "light-penetration mirrors" by the Chinese.[5][6]
This Tang-era book was lost over the centuries, but magic mirrors were described in the Dream Pool Essays by Shen Kuo (1031–1095), who owned three of them as family heirlooms.[5][6] Perplexed as to how solid metal could be transparent, Shen guessed that some sort of quenching technique was used to produce tiny wrinkles on the face of the mirror too small to be observed by the eye.[5][6] Although his explanation of different cooling rates was incorrect, he was right to suggest the surface contained minute variations which the naked eye could not detect; these mirrors also had no transparent quality at all, as discovered by the British scientist William Bragg in 1932. Bragg noted that "Only the magnifying effect of reflection makes them [the designs] plain".[5][6]
Japan
BearbeitenAs the manufacture of mirrors in China increased, it expanded to Korea and Japan. In fact, Emperor Cao Rui and the Wei Kingdom of China gave numerous bronze mirrors (known as Shinju-kyo in Japan) to Queen Himiko of Wa (Japan), where they were received as rare and mysterious objects. They were described as "sources of honesty" as they were said to reflect all good and evil without error. That is why Japan considers a sacred mirror called Yata-no-Kagami to be one of the three great imperial treasures.
Today, Yamamoto Akihisa is said to be the last manufacturer of magic mirrors in Japan. The Kyoto Journal [7] interviewed the craftsman and he explained a small portion of the technique, that he learned from his father.[7]
Western Europe
BearbeitenThe first magic mirror to appear in Western Europe was owned by the director of the Paris Observatory, who, on his return from China, brought several mirrors and one of them was magical. The latter was presented as an unknown object to the French Academy of Sciences in 1844.Vorlage:Citation needed In total, just four magic mirrors brought from China to Europe, but in 1878 two engineering professors presented to the Royal Society of London several models they had brought from Japan. The English called the artefacts "open mirrors" and for the first time made technical observations regarding their construction. Vorlage:Citation needed
In 2022, the Cincinnati Art Museum discovered that they had a Chinese magic mirror in their collection. The curator, Hou-mei Sung, discovered that a mirror in their collection reflected an image of Amitabha, an important figure in Chinese Buddhism, his name being inscribed on the back of the mirror.[8]
Einzelnachweise
Bearbeiten
Kategorie:Chinesische Erfindungen Kategorie:Bronzespiegel
- ↑ Magic Mirror with Image of the Buddha Amida. In: Met Museum. Abgerufen am 18. November 2022.
- ↑ Se-yuen Mak, Yip, Din-yan: Secrets of the Chinese magic mirror replica. In: Physics Education. 36. Jahrgang, Nr. 2, 2001, S. 102–107, doi:10.1088/0031-9120/36/2/302, bibcode:2001PhyEd..36..102M.
- ↑ Magic Mirrors. In: The Courier. Oktober 1988, ISSN 0041-5278, S. 16–17 (unesco.org [PDF; abgerufen am 23. August 2011]).
- ↑ W. Bragg, Die Welt des Lichtes, Vieweg, Braunschweig 1935, S. 28.
- ↑ a b c d e Referenzfehler: Ungültiges
<ref>-Tag; kein Text angegeben für Einzelnachweis mit dem Namen unesco-courrier. - ↑ a b c d e Temple, Robert (1986). The Genius of China: 3,000 Years of Science, Discovery, and Invention. New York: Simon and Schuster, Inc. p. 66-67 Vorlage:ISBN.
- ↑ a b The Magic Mirror Maker. In: Kyoto Journal. 4. Februar 2014, abgerufen am 13. Dezember 2020 (amerikanisches Englisch).
- ↑ 'Magic mirror': Hidden image revealed in reflection of centuries-old artifact. In: CNN. 13. Juli 2022.