De maculis solarib. et stellis circa Iouem errantibus, accuratior disquisitio ad Marcum Velserum, Augustæ Vind. II. virum perscripta; interiectis obseruationum delineationibus.
Augsburg: ad insigne pinus, 1612. 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’s disc, they moved more slowly near the limb, and their motion appeared to be parallel to the ecliptic. “Scheiner illustrated these conclusions by a discussion of his observations of individual spots, in the course of which he offered a general assumption about the nature of the Sun. Focusing on the speed of those spots moving parallel to and at some distance from the ecliptic, he inferred that they could not be attached to the solar surface, which he assumed was hard and unchanging. If the Sun were a solid body and the spots adhered to its surface, one would expect that a spot at a more northerly solar latitude would take exactly as much time to travel its shorter route across the face of the Sun as a spot on the ecliptic. Because this did not happen, and because Scheiner believed the Sun to be a solid body, he concluded that the spots could not be on its surface. “The spots’ constantly changing shapes reinforced this conclusion. Because the Sun was conventionally held to be a hard and unchanging globe, the ceaseless metamorphosis in the spots could be accommodated only beyond the solar body. The fact that the spots were darker near the limb than at the center appeared likewise to support this conclusion, for in the center of the Sun its most powerful perpendicular rays penetrated the material of the spots to some extent, and reached the eye. Such was not the case at the limb, as Scheiner demonstrated with a diagram similar to the one he had used in Tres epistolae to discuss the varying illumination of the spots. If the spots were on the surface in the form of chasms, they would necessarily appear darker near the center of the Sun and lighter near the limb. As Scheiner saw it, the spots were ‘shadow-casting bodies [that] wander around the Sun.’ “Scheiner went into great detail about the large spot μ, which he compared with the spot seen in 1607 by Kepler, who had supposed it to be Mercury, and depicted it in his Phenomenon singulare of 1609. Here his use of projection was clearly acknowledged, and the technique neatly clinched the argument that spots could not be caused by defects in the glass: the pinhole camera employs no lenses. “The conclusions of this letter showed Scheiner tentatively making his way toward a new cosmology, one engendered by recent telescopic discoveries. He compared sunspots to the Moon, and concluded that since the solar spots had uneven contours, conjectures about the roughness of the lunar body were not unreasonable. Though he drew the line at speculations about the inhabitants of Jupiter, Venus, Saturn, and the Moon – noting that ‘it would be absurd to place inhabitants on so many bodies’ – it now appeared to him unproblematic to grant that the Earth was not entirely dark but reflected some light, for sunspots were likewise dark bodies reflecting solar light. The fact that the spots allowed the passage of some sunlight also appeared to Scheiner to support a conventional argument for the Moon’s translucence, and perhaps to explain both that body’s secondary or ashen light, and the fact that it was not entirely dark during lunar eclipses. Scheiner argued that it was likely that heavenly bodies were of all different shapes but appeared round simply because of their remoteness, just as a candle flame seen from a great distance would appear round. Remarkably, Scheiner ended this fourth letter by claiming priority for the discovery of the solar phenomenon and for offering a correct explanation of it … “Having continued his study of sunspots and other heavenly bodies, toward the end of March 1612 Scheiner observed a star in the same field as the satellites of Jupiter, and his fifth letter, dated 14 April, was devoted to a discussion of these phenomena. The star appeared in a configuration with Jupiter and its satellites, as had the fixed star observed by Galileo and reported at the end of his observations of Jupiter in Sidereus nuncius. As in Galileo’s account, Jupiter and the star were moving with respect to each other, but if one assumed that the star was fixed, as Scheiner had initially done, then Jupiter’s motion was in the wrong direction. Scheiner concluded at last that the star was a satellite of Jupiter … Ignoring the fact that the four satellites of Jupiter always reemerged, he then drew a daring parallel between these bodies and his solar satellites. Beginning with the supposed new satellite, he broadened his scope, alleging that some of Jupiter’s stars suddenly appeared and disappeared ‘in almost the same way as the shadows [i.e., spots] on the Sun … Just as hitherto one spot always follows another, so the stars of Jupiter also appear’ … The pattern of their movement [i.e., of Jupiter’s satellites] was for Scheiner perhaps somewhat reminiscent of the irregular motion of sunspots. If one were to counter that the number of sunspots appeared to vary constantly, but that the number of Jovian satellites, by contrast, never exceeded four, Scheiner could now maintain that there were at least five bodies around Jupiter, and by implication many more. Jupiter and the Sun were arguably surrounded by swarms of like bodies moving in differently inclined orbits, and the apparent invisibility of the solar satellites beyond the Sun could be attributed to the immense brightness of that globe. As Scheiner presented it, solar satellites were simply part of the larger pattern of the planetary world. “Scheiner’s sixth letter – the third of Accuratior Disquisitio – also concerned the nature of sunspots. He had now read Galileo’s first letter, but he did not address it point by point, choosing instead to focus more generally on all possible objections raised against his own observations. He began with the hypothetical contention that such observations were mere illusions, and in what surely was the most complete discussion of this subject up to that point, he showed the various false appearances that could be caused by defects of the eye, flaws in the lenses of one’s instruments, and turbulence and vapors in the air. Scheiner again mentioned pinhole cameras, and this time added that sunspots could be observed by projecting the reflected image of the Sun onto a white wall or sheet of paper … “He also introduced Galileo as a witness to his own observations. Reproducing Galileo’s illustrations in his first sunspot letter of the irregular and changing shape of a spot, Scheiner stated that he, too, had seen this same spot on those dates, and he concluded that Galileo did not disagree with him at all about the rough shapes and configurations of spots, but only in the more precise task of rendering single spots. And because their observations, made in Italy and Germany, agreed so precisely, they ruled out any parallax for the spots. Thus, in about a page, Scheiner neatly disposed of Galileo’s first letter on the sunspots. “In Tres epitolae, Scheiner had stated his opinion that sunspots were as dark as the Moon, a judgment against which Galileo had argued in his first letter. Scheiner now discussed his observation of the lunar eclipse of May 1612, noting that in the center of the Earth’s shadow cone ‘not a speck of the lunar body’ could be seen. From this he inferred that the Moon was entirely without light of its own, and because the edge of the shadow showed no irregularities, that the unevenness of the Earth’s circumference could not be seen from afar. By implication, then, the mountains of the Moon’s periphery could not be discerned from the Earth. Scheiner also reiterated the claim that the sunspots were blacker than any of the nontelescopic spots of the Moon, and that therefore sunspots were as opaque as the Earth. “In May 1612 Scheiner had also observed an eclipse of the Sun, and this observation, too, was discussed in his letter of 25 July 1612. In his particular scrutiny of the sunspots during this event, he found the marks on the solar body to be as dark as the Moon. Scheiner also believed that he saw a weak light coming from the part of the Moon that was then covering the Sun, and from this he argued that the lunar body was somewhat translucent, as were sunspots, as was shown by the fact that they were less dark in the middle of the Sun’s disc than at the limb. The vexing question of the secondary light of the Moon was now answered; it was nothing but the light of the Sun pervading the Moon. He was skeptical, though not wholly dismissive, of Galileo’s hypothesis about the earthly origins of the Moon’s ashen glow: ‘But to me the reflection, if that is what it is, of terrestrial light does not appear to be so great that it produces this phenomenon, although this line of reasoning is entirely consistent with the principles of optics.’ “Scheiner had now taken issue with Galileo’s statements in Sidereus nuncius about both the satellites of Jupiter and the nature of the Moon. He had also attempted to show that Venus goes around the Sun by an argument independent from that of the phases. If any uncertainties remained about the scope of Scheiner’s aims, they were dispelled by his conclusion, in which he noted that the ‘solid constitution of the heavens cannot endure, especially in the heavens of the Sun and Jupiter,’ and stated that in the final edition of his works, the prominent Christoph Clavius has warned astronomers that ‘they must unhesitatingly provide themselves with another system of the world’” (Reeves & Van Helden, pp. 174-180). BL 17th C German S593; Carli and Favaro 54; Cinti 40; Gingerich, Rara astronomica 31; Jesuit science in the age of Galileo 2; Sommervogel VIII 736; Zinner 4379. Reeves & Van Helden, On Sunspots, 2010.
4to (190 x 135 mm), pp. 52 with woodcut printer’s device of a pine on title, and 12 engraved illustrations, one full-page, in text. Signed at end: Apelles latens post tabulam, vel, si mauis, Ulysses sub Aiacis clypeo. Latter plain wrappers.
Item #6463
Price: $15,000.00
