Regiomontanus (Johann Müller, 1436-1476) was a prominent mathematician, astronomer, and instrument maker, and a prolific author as well. His Kalendarium, first published in Nuremberg in 1474, became a popular reference. It eventually went through eight editions in three languages. Here are two sample images from the 1489 edition.
The calendar for December:
A discussion of eclipses:
The images above were obtained through the courtesy of the Erwin Tomash Library on the History of Computing, Charles Babbage Institute, University of Minnesota.
Erwin Tomash (1921-2012) was a pioneering computer scientist, helping launch the U.S. computer industry from the 1940s onward. During the 1970s he became interested in the history of computer science, and founded the Charles Babbage Society, and its research arm, the Charles Babbage Institute. The Institute, an archive and research center, is housed at the University of Minnesota. Its Erwin Tomash Library on the History of Computing began with Tomash's 2009 donation to the Institute of much of his own collection of rare books from the history of mathematics and computing. (Source: Jeffrey R. Yost, Computer Industry Pioneer: Erwin Tomash (1921-2012), IEEE Annals of the History of Computing, April-June 2013, 4-7.)
Index to Mathematical Treasures