Fresnel lens detail

Detail of a fresnel lens designed by David Stevenson for Inchkeith Lighthouse at the end of the 19th century and now part of the National Museum of Scotland on Chambers Street in Edinburgh. This first order dioptric holophotal revolving light showed a flash every half minute and made one complete revolution in four minutes.

Detail of a fresnel lens designed by David Stevenson for Inchkeith Lighthouse at the end of the 19th century and now part of the National Museum of Scotland on Chambers Street in Edinburgh. This first order dioptric holophotal revolving light showed a flash every half minute and made one complete revolution in four minutes.

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