cassini gian domenico (1 résultats)

First edition. CASSINI'S EXTREMELY RARE FIRST PUBLISHED WORK - PROVING THAT COMETS ARE CELESTIAL PHENOMENA. First edition, exceptionally rare, of the remarkable first publication of the great observational astronomer Gian Domenico Cassini, in which he demonstrated for the first time by observing their parallax that comets are celestial phenomena and not, as Aristotle had claimed, ignited exhalations from the earth (the comet is now designated C/1652 Y1). We have been unable to trace any other copy of this work in commerce, and only a handful of institutional copies. In 1652, just before Christmas, a comet was observed approaching the Earth, and it remained visible through the first week of January 1653. Cassini was then a guest in the astronomical observatory of his patron, the Marquis Cornelio Malvasia, inside the Villa di Panzano, near Castelfranco Emilia. Here, together with Malvasia and, occasionally, the Duke of Modena, Cassini spent many cold winter nights taking, with the observatory's telescope, accurate measurements of the comet's position, and elaborating a theory on its origin: "the observations I made [of the comet] authorized me to conclude that it had no sensible parallax and that it was above [the orbit] of Saturn." Each of Cassini's observations is accompanied by an engraved illustration in the text showing the position of the comet with respect to certain reference stars. The last two pages are dedicated to the description of the instrument at Panzano, illustrated on a beautiful engraving, used to determine the position of the comet with respect to these reference stars. The operation of the large instrument required two observers and several assistants. "From a series of observations on the comet of 1652, made with the Marquis of Malvasia, who had been instrumental in bringing him to Bologna, he concluded that comets were not of a meteoric nature as had been imagined, but that they were guided in their paths by the same laws as the planetary bodies; and he explains the motion of the comet by a circle described around the earth and beyond the orbit of the moon. These observations were published in his first production, which appeared in 1653, under the title of De cometa anni 1652 et 1653" (Brewster, The Edinburgh Encyclopaedia (1830), p. 603). The comet of 1652 was also observed by Hevelius in Gdansk between December 20 and January 8; Hevelius devotes the whole of the first book of his Cometographia (1668) to this comet: "he had an ingenious but inaccurate way of judging parallax and greatly underestimated the comet's distance . He supposed comets to be condensed planetary exhalations" (DSB). The comet's true parabolic orbit was calculated by Edmond Halley in his Synopsis (1705), using 54 observations (including those of Cassini). OCLC lists five copies worldwide (Brown, Adler Planetarium, Oklahoma, Bayerische Staatsbibliothek, Institut de France); KVK adds the Archiginnasio Municipal Library, Bologna, and University of Florence, and there is also a copy in the Astronomical Observatory in Brussels; not on COPAC (not in the British Library). "The first of a family of astronomers who settled in France and were prominent in directing the activities of the French school of astronomy until the Revolution, Cassini (1625-1712) . studied at Vallebone and then at the Jesuit college in Genoa and at the abbey of San Fructuoso. He showed great intellectual curiosity and was especially interested in poetry, mathematics, and astronomy. He was attracted at first by astrological speculations, but reading Pico della Mirandola's pamphlet Disputationes Joannis Pici Mirandolae adversus astrologiam divinatricem persuaded him of the frivolity of that pseudoscience. Yet, paradoxically, the beginning of his scientific career benefited from the reputation he acquired for his knowledge of astrology. The Marquis Cornelio Malvasia, a rich amateur astronomer and senator of Bologna who calculated ephemerides for astrological purposes, invited him to come to work in his observatory at Panzano, near Bologna . Thanks to the marquis's aid, he made use, from 1648, of several instruments that allowed him to begin his first researches. He was also able to complete his education under the tutelage of two excellent scientists, the Bolognese Jesuits Giovan Battista Riccioli-who was then finishing his great treatise, the Almagestum novum (1651)- and Francesco Maria Grimaldi, who later became famous for his discovery of the phenomenon of diffraction, published in his posthumous work De lumine (1665). Although one cannot exactly determine their influence on the young Cassini, it appears that they convinced him of the importance of precise and systematic observation and of the necessity of a parallel improvement in instruments and methods. They probably likewise contributed, less happily, to making him wary of the new theories-especially of Copernicus' system-and to reinforcing in him the conservative tendencies that he displayed throughout his life.With his first works Cassini won the esteem of his fellow citizens to such an extent that in 1650 the senate of Bologna, on the recommendation of its patron, designated him to occupy the principal chair of astronomy at the university, which had been vacant since Bonaventura Cavalieri's death in 1647 . In 1652-1653 the passage of a comet attracted his attention" (DSB) "In 1652, just before Christmas, a comet was noticed approaching the earth. From the city of Bologna, it was visible at the zenith, and it was observed also by the archbishop of the city. As reported by Cassini in his memoirs, this circumstance required again his presence at the castle of Panzano, by request of Malvasia: 'the Marquis Malvasia absolutely wanted that I come with him and my student Beringelli Geri to his home in Panzano'. "Cassini thus relocated to the Panzano castle, far from the city, which actually hosted a very well-equipped observatory that would enable him to make better observations. One can appreci.