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First edition, rare, of Scheiner s second series of letters on sunspots and the satellites of Jupiter. This is one of the first books containing telescopic observations and illustrations, and is a fundamental text for the history of the telescope and Galilean studies. "[Scheiner (1573-1650)] was appointed professor of Hebrew and mathematics at Ingolstadt in 1610. The following year Scheiner constructed a telescope with which he began to make astronomical observations, and in March 1611 he detected the presence of spots on the sun. His religious superiors did not wish him to publish under his own name, lest he be mistaken and bring discredit on the Society of Jesus; but he communicated his discovery to his friend Marc Welser in Augsburg. In 1612 Welser had Scheiner s letters printed under the title Tres epistolae de maculis solaribus, and he sent copies abroad, notably to Galileo and Kepler. Scheiner believed the spots were small planets circling the sun; and in a second series of letters, which Weiser published in the same year as De maculis solaribus . accuratior disquisitio, Scheiner discussed the individual motion of the spots, their period of revolution, and the appearance of brighter patches or faculae on the surface of the sun. Having observed the lower conjunction of Venus with the sun, Scheiner concluded that Venus and Mercury revolve around the sun. Welser had concealed Scheiner s identity under the pseudonym of Appeles latens post tabulam. Galileo, however, identified Scheiner as a Jesuit and took him to task in three letters addressed to Welser and published in Rome in 1613 [Istoria e dimostrazioni intorno alle macchie solari]. Galileo claimed priority in the discovery of the sunspots and hinted darkly that Scheiner had been apprised of his achievement and was guilty of plagiarism" (DSB). Scheiner concluded that "A new world system was called for, one where Mercury and Venus, and perhaps other bodies, went around the Sun, and where the regions about the Sun and Jupiter, and probably Saturn as well, were filled with numerous planetary bodies" (Reeves & Van Helden, p. 181). Galileo s sunspot letters were published in two issues, one of which contains an appendix reprinting the two Scheiner works (but with illustrations inferior to the originals). OCLC lists, in the US: Cal Tech, Yale, Adler, Harvard, Johns Hopkins, Linda Hall, Duke, Cornell, and Rice. ABPC/RBH list six copies, all in modern bindings except the Macclesfield copy, which was part of a sammelband. The present work, On solar spots and the stars wandering around Jupiter; a more accurate enquiry "began with a long and quite superfluous geometrical demonstration about internal and external angles of triangles. Scheiner then proceeded to use this demonstration in an exhaustive geometrical explanation of the conjunction of Venus of 11 December 1611, the timing of which he had misjudged [in Tres epistolae] in his use of Magini s Ephemerides … Having thus shown himself to be a perfectly capable mathematician, and having reduced his error to an incidental oversight, Scheiner returned to the sunspots. As before, he presented his second series of observations, from 10 December 1611 to 12 January 1612, in a group of small diagrams in which the sizes of the spots were exaggerated … He made a number of important points, alleging that the spots were rarely spherical, that they were almost constantly changing their shapes, that they appeared largest in the middle and narrowest near the limb, and that they could not usually be seen at the limb, but appeared and disappeared a little distance from it. He also noted that the spots split up, coalesced, and were often temporarily surrounded by groups of other very small spots, that such groupings were more compact near the limb, and rather loose near the center, and that they had rough edges, and were darker at their center and lighter at their borders. Some spots were darker near the limb than towards the center of the Sun .
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