Hugo GYLDÉN (Helsinki 1841 - Stockholm 1896),... - Lot 33 - Conan Belleville Hôtel d'Ainay

Lot 33
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300 - 400 EUR
Hugo GYLDÉN (Helsinki 1841 - Stockholm 1896),... - Lot 33 - Conan Belleville Hôtel d'Ainay
Hugo GYLDÉN (Helsinki 1841 - Stockholm 1896), Finnish-Swedish astronomer. A crater of the Moon bears his name. Autograph letter signed to the astronomer Ernest Mouchez. 4 pp. in-8. Stockholm, January 2, 1889. Photographic cartography of the sky with plates of the Lumière brothers. "Allow me to communicate to you a few words concerning the astrophotographic tests that we started here with very modest devices. The observatory of Stockholm acquired a small objective of Mr. Steinheil acromatized for the chemical rays. The diameter of the lens is only 81 mm and its focal length is only one meter, but on the other hand our pictures will cover about 15 square degrees of the sky. In spite of the small size of our instrument, we have succeeded, by using plates of Messrs. Lumières of Lyon, to obtain stars of 13th and even, perhaps of 14th magnitude. On the image of such a photograph obtained by means of a "lanterna magica" one can distinguish immediately and without difficulty the stars of 12th magnitude, so that it would be very easy to make a celestial map [...]".
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