In the 1870s, the Japanese government built lighthouses with rotating lights. Some of these Meiji era lighthouses are still in use today.
Eight lighthouses were first brought into service in the 1870s with the same mechanical light rotating system. This apparatus was designed and manufactured in Scotland; and then the equipment was shipped to Japan. The Japanese government hired Richard Henry Brunton to oversee this technology transfer process.-- see Richard Brunton (1991). "Building Japan: 1868-1876," pp. 24-25. https://books.google.com/books?id=q6GOdFknNDYC&printsec=frontcover#v=onepage&q&f=false
The heavy glass lens mechanism is only part of the optical instrument assembly in Japanese lighthouses built using European designs.
The heart of the lighthouse is the light rotation apparatus which moves the lens. In the earliest Western-style lighthouses, the bulk of the lens and rotation gear is supported in a mercury bath. Mercury was used because of its low rotation friction. -- see Japan Coast Guard, Maritime Safety Department, "Past and Present of the Aids to Navigation of Japan," p. 6 (PDF p. 7 of 12) https://www.kaiho.mlit.go.jp/e/image/41_the%20aids%20to%20navigation%20of%20japan.pdf
In the mechanical drawing below, the mercury bath is shown below in blue.
QUESTION: The fact that the Japanese lighthouse apparatus was modeled on equipment used in Scotland begs a few questions -- for example, where were similar mercury bath pedestal support mechanisms in use in Scotland in the 1870s? Are there sites where this 19th century technology is still in use in the United Kingdom?
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