Western Europe įor many centuries, the 'magic' of these mirrors baffled both lay people and scientists, who devoted themselves to do different research work on this subject. The Kyoto Journal interviewed the craftsman and he explained a small portion of the technique, that he learned from his father. Today, Yamamoto Akihisa is said to be the last manufacturer of magic mirrors in Japan. That is why Japan considers a sacred mirror called Yata-no-Kagami to be one of the three great imperial treasures. They were described as 'sources of honesty' as they were said to reflect all good and evil without error. 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. Japan Īs the manufacture of mirrors in China increased, it expanded to Korea and Japan.

Bragg noted that 'Only the magnifying effect of reflection makes them plain'.

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 (after an entire century of their confounding Western scientists). 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. 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 a family heirloom. In 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.

Michael Berry has written a paper describing the optics and giving some photos. 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.' 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. Finally, a mercury amalgam was laid over the surface this created further stresses and preferential buckling.

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. The surface was then polished to become shiny. Robert Temple describes their construction: '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. Bronze mirrors were the standard in many Eurasian cultures, for example ancient Rome, but most lacked this characteristic, as did most Chinese bronze mirrors.

Japanese magic mirror