APHRODITOGRAPHISCHE FRAGMENTE, ZUR GENAUERN KENNTNIß DES PLANETEN VENUS

Helmstedt: Printed and commissioned by C. G. Fleckeisen, 1796. FIRST EDITION. 275 x 225 mm. (10 3/4 x 9"). XVI, 250, [2] pp.
Contemporary brown paste paper boards, smooth spine with red roan label. WITH 10 ENGRAVED PLATES, one folding, by "G. T." after Schröter. Honeyman 2825; de la Lande, p. 635; Poggendorff II, 846; cf. DSB XII, p. 226, NDB XXIII, 590 (Schröter) and 510 (Schrader). See also Sheehan and Baum, "Observations and inference: Johann Hieronymous Schroeter, 1745-1816," Journal of the British Astronomical Association, vol.105, no.4, p.171-175. Joints and extremities somewhat rubbed, boards with a hint of chafing, occasional very minor foxing (including to the final plate), half a dozen leaves with faint dampstain to head edge, but a really excellent copy, the other plates clean and bright, the text especially clean and fresh, and the binding entirely sound.

This is a very rarely seen early work on the topography of Venus, written by the astronomer who first observed the planet's so-called phase anomaly, and illustrated with 10 folding plates. One of a series of "fragments" Schröter published--the others concerning the sun, the moon, Saturn, and Mercury--"Aphroditographische Fragmente" discusses the author's observations of Venus' surface (at the same time coining the term "Aphroditographie" in reference to the Greek version of the goddess' name). The most important observation contained in our work concerns the phases of Venus: like the moon, Venus appears to wax and wane when observed through a telescope. However, due to the thickness of its atmosphere, the planet will always appear less full than mathematical calculations indicate it should be. This phenomenon, known as Venus' phase anomaly--or the Schröter Effect--first observed by the man who gave it its name in 1793, is discussed in detail in this text, which is accompanied by highly detailed plates. Eight of these are focused on Venus, primarily depicting its phases; another is a diagram of the telescope; and the other depicts the Orion Nebula, to which there is a short addendum. Schröter (1745-1816) built a state-of-the-art observatory at Lilienthal in Lower Saxony, equipped with the largest telescopes available at the time. One such instrument, which he built in his own workshop, was an impressive 27-foot telescope discussed in the present work, which has sometimes been incorrectly credited to Schröter's colleague William Herschel (1738-1822). Schröter made systematic long-term observations of the surfaces of the moon and planets, something DSB tells us he was the first to do. Not everything he discovered or asserted turned out to be true. Based on his findings, he posited the existence of a mountain range on Venus' surface and suggested a rotation period for the planet. Both subsequently were disproven (modern scientists have suggested that Schröter's "mountain" may have been an overly optimistic observation of a cloud formation), but like the rest of his work, they demonstrated the commitment to observational astronomy that leads astronomy historians William Sheehan and Richard Baum to call Schröter "the man who laid the foundations of planetology and modern selenography." His long and impressive astronomical career came to an unfortunate end in 1813, when during the Napoleonic invasion, the French reportedly set fire to his observatory. His library, instruments, unpublished notes, and copies of many of his works, which were published in small runs at his expense, were said to have been destroyed in the fire, a fact that may partly explain the current rarity of our book. We have been able to trace at auction only an ex-library copy of the book with significant condition problems that sold in 1981 for a hammer price of £260; the fact that such an unattractive copy came from the distinguished Honeyman collection reinforces how difficult the work is to obtain..