In this newsletter we report the latest additions to our Virtual Museum: two interesting books (French and Dutch editions) and a beautiful horizontal goniometer of the Babinet type.
The rare and much esteemed "Le Mercure indien ou le trésor des Indes" was written by the Parisian goldsmith Pierre de Rosnel "orfèvre ordinaire du Roy" and published in 1667.
The title of the book is interesting. In Roman mythology, Mercury (Hermes for the Greeks) is the god of commerce but also the messenger of the gods: he conveys the news of the gods. By extension, the name of Mercury is associated with the beginning of the periodical press, which is responsible for bringing the news. At the end of the Renaissance there are newspapers with the names "Mercure de France", "Mercurius Politicus", "Mercure Galant" etc ...
We find the same meaning in Rosnel’s title "Le Mercure Indien"which does not refer to the metal mercury (Hg) but provides information about the metals, minerals and gems of the "East" and "West" Indies.
The book consists of one volume in three parts. The first part is a treatise on the mining and metallurgy of gold, silver and mercury, among others, with an emphasis on the mines of the New World ("Indes Occidentales").
The second part, which most interests the gemologist, deals with the then supposed origins of gems and describes some precious stones (diamond, ruby, spinel, pearls, agate ...) with documented descriptions and detailed information about their localities.
The last part of the book contains a treatise on the valuation of cut diamonds (based on a mathematical system that anticipates later ones) and other gems described earlier in the text.
Sinkankas provides a comprehensive description of Rosnel's book in his annotated bibliography of gemology. This copy is the 4to edition of Rosnel's work, the 8vo edition was already in our "collection".
The unusual "Verzameling van Verscheide Vertoogen over den Aschtrekker" (Amsterdam 1773), is an illustrated Dutch edition (translated from French) of Aepinus’ collection of memories on tourmaline. Franz Aepinus reports his experiments on the electrical properties of tourmaline (tourmaline crystals attract ash due to static electricity hence the name "aschtrekker" in the book). The author was, among others, a member of the Russian Academy of Sciences in St Petersburg.
A large height-adjustable Babinet-type goniometer from the 4th quarter of the 19th century, in excellent condition; it is signed by the Parisian maker Edouard Lutz who has built numerous instruments for scientific observations and tests (e.g. physical and mineralogical optics).
This beautiful and rare instrument comes from the impressive collection of 18th and 19th century scientific instruments from our enthusiastic and loyal Californian collector. Beautiful, high-resolution photos of this Babinet goniometer, a detailed description of the components and an interesting translation of Lutz's introduction from his 39-page catalog (dated 1872) are provided on the owner's personal website
Note the specimen holder which consists off a black glass plate. This specimen holder allows the instrument to be used for different purposes. It was useful for measuring crystals on matrix. The mineral sample could be attached to the glass support using wax. But the Babinet was also used for spectroscopy, in which case a glass prism was simply placed on the glass plate. And another application was to measure refractive indices of crystals.
Claude Hootelé, Paul Tambuyser