Newsletter 2024 /2

Among the new objects recently introduced to our virtual museum, three stand out: two full-circle contact goniometers and an extraordinary multi-prism spectroscope

Full-Circle Contact Goniometers
Goniometers, used to measure the angles of crystals, come in a fascinating array of designs. Our virtual museum showcases a diverse range of these instruments, but the full-circle contact goniometers are especially rare. Prior to this update, our collection included two such instruments: one signed by the Parisian firm Nachet and another unsigned.

We are now pleased to introduce two additional full-circle contact goniometers, courtesy of Mr. Stefan Nicolescu, Collection Manager of the Division of Mineralogy and Meteoritics at the Yale Peabody Museum.

Both goniometers, crafted by the 19th-century mathematical instrument maker Wilhelm Lingke of Freiberg, feature detachable arms and come in leather-covered cases. One instrument is signed, while the other -unsigned- was undoubtedly produced by Lingke as well.

The provenance of these goniometers adds to their significance:

• the unsigned instrument belonged to Professor James Dwight Dana (1813–1895), the celebrated author of *The System of Mineralogy* (first published in 1837)
• the signed Lingke goniometer was owned by Professor George Jarvis Brush, the first curator of the Yale Peabody Museum

A historical note: In his 1998 review on goniometers (*Mineralogical Record*, Vol. 29, No. 6), Ulrich Burchard speculated on the purpose of full-circle instruments. He proposed that their design might have allowed users to average out errors by taking measurements from both readings on the full circle.

Spectroscope
We are excited to feature an extraordinary universal automatic spectroscope with six dispersion prisms, contributed by our permanent collaborator, Mark McElyea.

This exceptional instrument, crafted circa 1885 by John Browning, reflects the unparalleled quality associated with this renowned English manufacturer of spectroscopes. The spectroscope is in excellent original condition and represents a pinnacle of 19th-century optical craftsmanship.

For more details and photos of this extraordinary piece, visit *MM Instruments*.

Books
Our collection has also expanded to include an early mineralogical work by Henri Lambotte. Published in 1842, shortly after Belgium gained independence in 1830, this concise treatise on general descriptive mineralogy is one of the first mineralogy books published in Belgium.

Claude Hootelé, Paul Tambuyser
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