Johannes Hevelius, 1654

The definitive mapping of lunar libration
Johannes Hevelius, 1654
HEVELIUS, Johannes (1611-1687). Epistolae II. Prior: de motu lunae libratorio, in certas tabulas redacto ... Posterior: de utriusque luminaris defectu anni 1654. Danzig: Andreas Julius Moller for the author, 1654.

Hevelius's definitive mapping of lunar libration. "Hevelius' descriptions of a librational cycle of shadow changes in the lunar details, his method of judging the libration by means of changes in the apparent (telescopic) separation of a pair of lunar details, and his introduction of rudimentary lunar coordinate systems provided a sound basis for the work of subsequent astronomers" (DSB). Following upon his 1647 lunar atlas, the Selenographia, Hevelius published these four scientific papers, presented as correspondence: on the solar eclipses of 1649 and 1652, on lunar libration, and on the double-eclipses of 1654. New engraved plates graphically reproduced the astronomical events that had occured in the intervening years. Norman 1065.

Folio (344 x 224mm). Engraved title vignette; 6 engraved plates by Hevelius, including a double-page plate from the Selenographia; one engraved diagram in text; letterpress astronomical tables; woodcut initials (first 2 leaves loose, light waterstaining to the inner lower corner of quire A, occasional light browning, inner upper corner of the front free end-paper torn).18th-century morocco-backed marbled boards (joints cracked, spine chipped and worn, edges rubbed). Provenance: Collection of Peter and Margarethe Braune (bookplate).