Krämer-BadoniRudolf, Galileo Galilei (Munich and Berlin, 1983), 66–69; WestfallR. S., address to 1983 annual meeting, Norwalk, Connecticut, of the History of Science Society.
2.
Opere di Galileo Galilei, ed. nazionale, ed. by FavaroA. (Florence, 1890–1910 and later printings), x, 427–8. To avoid inconvenient notes, further citations from this work are identified by volume and page numbers in the text. Letters cited are from vols x and xi; since those are arranged chronologically, dates of letters mentioned in passing suffice for finding them in the Opere.
3.
KeplerJohann, Narratio de observatis a se… (Frankfurt, 1611), reproduced in Galileo, Opere, iii, 182–90. Year on the original title-page is misleading, printing having been apparently completed in October 1610.
4.
Jupiter was then reappearing after inferior conjunction. Galileo's letter dated 1 October (see above) implies that Santini had made evening observations of Jupiter also, probably months earlier.
5.
Born at Lucca in 1577, Santini moved to Venice in 1603. His first known letter to Galileo was in 1608 and concerned mathematics. In 1612 he moved to Rome, where he soon entered a religious order, and was later in Milan, where he met B. Cavalieri; subsequently he became professor of mathematics at the Sapienza in Rome.
6.
CarlosE. S., The sidereal messenger… (London1880, repr. London, c. 1960), 91. Modified translations from the same source have been used for some other passages in the preface to Kepler's Dioptrice.
7.
Probably Santini's early telescopes, like the Galilean instrument sent to the Elector of Bavaria, gave oblong planetary images. One of the two telescopes preserved as Galileo's at the museum of history of science in Florence does the same.
8.
Travel between Venice and Rome should not have taken more than five days; it is not always certain that a letter left a city the same day it was dated, or that it was in the hands of the addressee the same day it reached his city. In this instance the Roman observation on 27 November and its copying for Galileo at Venice permit reliable setting of limits.
9.
DrakeS., “Galileo and satellite prediction”, Journal for the history of astronomy, x (1979), 75–95.
10.
The letter is in Opere, xi, 31–35; information here summarized from it is on p. 34. Grienberger opined that Galileo's telescope might have greater magnifying power than the one sent to Rome by Santini; on the contrary, it probably had lower power and wider field of view, Galileo's favourite instruments having been about 20×.
11.
Simon Mayr is best known for his claim in 1614 to have observed Jupiter's satellites before Galileo. Independent evidence is lacking that he began observations before the lunar eclipse of 29 December 1610, for which he may have used the telescope that Kepler borrowed earlier from the Elector of Bavaria. Documents relating to this and to Mayr's complaints about Kepler's treatment of discovery of the phases of Venus can be found in Joannis Kepleri opera omnia, ed. by FrischCh., ii (Frankfurt and Erlangen, 1859), 469–81.
12.
On the contrary, had Galileo received Castelli's letter of inquiry by 11 December, the most natural course would have been simply to reply to it directly, saying that he had indeed already made observations of Venus and expected soon to see it hornéd. That would have secured him a speedier favourable testimony of priority, if one were needed, and from an Italian churchman to boot, if any contest had been made by Jesuits at Rome. (Of course such a reply would be now treated by Galileo's German and American critics as an egregious lie, just as is his actual letter to Prague. Nothing Galileo could have done would prevent such charges by those who like to make them, which is important for readers to recognize in evaluating the historical evidence).
13.
See Opere, xi, 15–16.
14.
Op. cit. (ref. 11), 465.
15.
DrakeS. and O'MalleyC. D., The controversy on the comets of 1618 (Philadelphia, 1960), 184 (translated from Galileo, Il saggiatore).
16.
Ibid., 344 (translated from Kepler's Hyperaspistes, appendix).
