The lens on display in the British Museum
|Size||Diameter: 38 mm (1.5 in)
Thickness: 23 mm (0.9 in)
|Place||North West Palace, Room AB|
|Present location||British Museum, London|
The Nimrud lens or Layard lens is a 3000-year old piece of rock crystal, which was unearthed by Austen Henry Layard at the Assyrian palace of Nimrud, in modern-day Iraq. It may have been used as a magnifying glass, or as a burning-glass to start fires by concentrating sunlight, or it may have been a piece of decorative inlay.
The lens is slightly oval, and was roughly ground, perhaps on a lapidary wheel. It has a focal point about 110 millimetres (4.5 in) from the flat side, and a focal length of about 12 cm. This would make it equivalent to a 3× magnifying glass. The surface of the lens has twelve cavities that were opened during grinding, which would have contained naptha or some other fluid trapped in the raw crystal. The lens is said to be able to focus sunlight although the focus is far from perfect. Because the lens is made from natural rock crystal the material of the lens has not deteriorated significantly over time.
The Nimrud lens is on display in the British Museum.
The function of the lens is not clear, with some authors suggesting that it was used as an optical lens and others suggesting a decorative function.
Assyrian craftsmen made intricate engravings, and could have used a magnifying lens in their work. The discoverer of the lens noted that he had found very small inscriptions on Assyrian artefacts which he suspected had been achieved with the aid of a lens.
Italian scientist Giovanni Pettinato of the University of Rome has proposed that the lens was used by the ancient Assyrians as part of a telescope, and that this explains their knowledge of astronomy (see Babylonian astronomy). Experts on Assyrian archaeology are unconvinced, doubting that the optical quality of the lens is sufficient to be of much use. The ancient Assyrians saw the planet Saturn as a god surrounded by a ring of serpents, which Pettinato suggests was their interpretation of Saturn's rings as seen through a telescope. Other experts say that serpents occur frequently in Assyrian mythology, and note that there is no mention of a telescope in any of the many surviving Assyrian astronomical writings.
According to his book, Layard found the lens buried beneath other pieces of glass which looked like the enamel of an object, perhaps made of wood or ivory, which had disintegrated. The British Museum curator's notes propose that the lens could have been used "as a piece of inlay, perhaps for furniture", and that there is no evidence that the Assyrians used lenses for their optical qualities, e.g. for magnification or for starting fire.
See also 
- Layard, Austen Henry (1853). Discoveries in the ruins of Nineveh and Babylon: with travels in Armenia. G.P. Putnam and Co. pp. 197–8,674.
- D. Brewster (1852). "On an account of a rock-crystal lens and decomposed glass found in Niniveh". Die Fortschritte der Physik (in German) (Deutsche Physikalische Gesellschaft).
- "The Nimrud lens / the Layard lens". Collection database. The British Museum. Retrieved Oct. 21, 2012.
- Whitehouse, David (July 1, 1999). "World's oldest telescope?". BBC News. Retrieved May 10, 2008. "If one Italian scientist is correct then the telescope was not invented sometime in the 16th century by Dutch spectacle makers, but by ancient Assyrian astronomers nearly three thousand years earlier. According to Professor Giovanni Pettinato of the University of Rome, a rock crystal lens, currently on show in the British museum, could rewrite the history of science. He believes that it could explain why the ancient Assyrians knew so much about astronomy."
- "World's oldest telescope?". EXN Science Wire. June 29, 1999. Archived from the original on Sept. 29, 2007. Retrieved 2008-05-10. "Pettinato believes the lens was used by Assyrian astronomers as a telescope more than three thousand years ago. They saw more in the night sky than was possible with the naked eye alone. For example, the Assyrians saw the planet Saturn as a god surrounded by a ring of serpents. Pettinato says that would be a logical assumption to make if they saw Saturn's rings through a primitive telescope."
- A. H. Layard, Discoveries in the Ruins of Nineveh and Babylon (London, 1853), p. 197–98.