Crüger to Müller, 4/14 December 1629
Peter Crüger, “Crüger to Müller, 4/14 December 1629,” Nova Kepleriana 4, December 14, 1629, 109–110, transcribed in Plain Old Text, https://sources.vjbe.net/stable/48mb9.
Nova Kepleriana 4 14 Dec, 1629, p. 109–110 Summary
Part of Die Keplerbriefe auf der Nationalbibliothek und auf der Sternwarte in Paris
Having worked through the *Rudolphine Tables*, Crüger tells Müller that further work on the *Astronomia Danica* is now pointless, praises the tables' methods and logarithms, and is no longer averse to elliptical orbits.
Source: Peter Crüger's letter to Philipp Müller of 4/14 December 1629, written after he had received Kepler's Rudolphine Tables. The original is in the Bibliothèque de l'Observatoire, Paris (Delisle collection, 89, 9. N. 35). Printed in extracts in Nova Kepleriana 4, ed. Walther von Dyck and Max Caspar, Abhandlungen der Bayerischen Akademie der Wissenschaften, Math.-naturw. Abteilung 31, no. 1 (Munich, 1927), 109–110.
English translation of the Latin extracts printed in Nova Kepleriana 4 (1927), made for Plain Old Text. Each paragraph translates the corresponding extract of the original; the omission marks (…) are the 1927 editors’, and words in square brackets are theirs. Italics follow the editors’ emphasis.
Greetings. It is time, most famous and most excellent Sir, that I made up for my silence with a good long letter, if the matter allows. You have bound me to you by many kindnesses, by sharing many new things. I have nothing to offer in return but bare talk about our common studies, for in this corner of Europe the Muses, especially in these times, are not as fertile as in Germany, where they bring forth something new almost every day. I do what I can: I thank you warmly for sharing not only the writings published in print, but also Bartsch’s letter to you. With your leave, I shall talk with you briefly here about all of these.
First, though, about the Astronomia Danica, which you mention at the very start of your last letter. You wish that someone would take a file to those tables, and say this would please the whole company of astronomers. But I would think this effort wasted, now that the Rudolphine Tables are published, which everyone will doubtless follow, above all since they have banished all the old tangled speculations about the planets’ inclinations, reflexionsReflexiones: a term of the Ptolemaic theory of planetary latitudes. and the like.
For my part, as far as my other, less liberal occupations allow, I am wholly taken up with learning to understand the foundations of the Rudolphine rules and tables thoroughly, and I am doing it from the Epitome AstronomiaeKepler's Epitome Astronomiae Copernicanae (1617–1621), a textbook of Copernican astronomy in questions and answers, which set out his laws of planetary motion for all the planets., which Kepler published earlier as a forerunner. Before the tables came out I read it many times, understood little of it, and often threw it aside; now I take it up again and get on somewhat better, since I can compare it with the Tables and it is made clear by them.
And now I will tell you in confidenceLiterally “in your ear” (in aurem). what pleases me about these new Tables, and also what displeases me, especially since you asked me for this yourself in your earlier letter, which I could not do before I had seen and worked with the Tables.
I like that the eccentric [illegible] of every planet without exception is tied, constantly and unchangeably, to the great orb (whether of the sun or of the earth);Orbis magnus, Copernicus's name for the earth's orbit. By adding “whether of the sun or of the earth” Crüger leaves open whether the sun goes round the earth, as for Tycho, or the earth round the sun. I like the constant inclination of the eccentrics of all [illegible] to the ecliptic; the simple [illegible] account of the latitudes; the method, the same for the five planets, apart from the luminaries [sun and moon]; the uniform motion of the nodes [illegible]; and finally the shorter computation by logarithms, which, as it did to you, seemed confusing at first and easy to slip in, but which use has now made familiar. Nor do I any longer shrink from the elliptical form of the planetary orbits, persuaded above all by Kepler’s demonstrations in the Commentaries on Mars.
Besides, these Rudolphine Tables contain things excellently discovered and wonderfully pleasing. Still, I shall say what displeases me …
Nor is the chronology all to my taste. I laughed when I read the Time of the Creation: after troubling the places and apogees of the planets for so many years, shaping and reshaping them, he now at last turns from technician into historian.The Rudolphine Tables date the Creation, an epoch Kepler fixed partly from chronology rather than astronomy. But this has nothing to do with astronomy.
These are the things I wanted to discuss with you this time about the Rudolphine Tables, most excellent Sir, but privately and as to a friend, so that the Author does not find out, for I hold him in high esteem, as is only right.
The Ephemerides, which he and Bartsch promise us, will be most welcome; I only hope they come at a bearable price. I am surprised that the booksellers (as the letters of Kepler and Bartsch show) buy copies of the Rudolphine Tables from Kepler at two thalers and then sell them on at four. What will become of the Ephemerides? I am sending Götz the money for the Rudolphine Tables and so on; if the Ephemerides have come out, please write and tell me what they sell for …