by his widow Ethel Voynich, author of the novel The Gadfly and daughter of mathematician George Boole. She died in 1960 and left the manuscript to her close friend Anne Nill. In 1961, Nill sold the book to antique book dealer Hans P. Kraus. Kraus was unable to find a buyer and donated the manuscript to Yale University in 1969, where it was catalogued as "MS 408", sometimes also referred to as "Beinecke MS 408". Timeline of ownership The timeline of ownership of the Voynich manuscript is given below. The time when it was possibly created is shown in green (early 1400s), based on carbon dating of the vellum. Periods of unknown ownership are indicated in white. The commonly accepted owners of the 17th century are shown in orange; the long period of storage in the Collegio Romano is yellow. The location where Wilfrid Voynich allegedly acquired the manuscript (Frascati) is shown in green (late 1800s); Voynich's ownership is shown in red, and modern owners are highlighted blue. Authorship hypotheses Many people have been proposed as possible authors of the Voynich manuscript, among them Roger Bacon, John Dee or Edward Kelley, Giovanni Fontana, and Voynich. Early history Marci's 1665/1666 cover letter to Kircher says that, according to his friend the late Raphael Mnishovsky, the book had once been bought by Rudolf II, Holy Roman Emperor and King of Bohemia for 600 ducats (66.42 troy ounce actual gold weight, or 2.07 kg). (Mnishovsky had died in 1644, more than 20 years earlier, and the deal must have occurred before Rudolf's abdication in 1611, at least 55 years before Marci's letter. However, Karl Widemann sold books to Rudolf II in March 1599.) According to the letter, Mnishovsky (but not necessarily Rudolf) speculated that the author was 13th-century Franciscan friar and polymath Roger Bacon. Marci said that he was suspending judgment about this claim, but it was taken quite seriously by Wilfrid Voynich, who did his best to confirm it. Voynich contemplated the possibility that the author was Albertus Magnus if not Roger Bacon. The assumption that Bacon was the author led Voynich to conclude that John Dee sold the manuscript to Rudolf. Dee was a mathematician and astrologer at the court of Queen Elizabeth I of England who was known to have owned a large collection of Bacon's manuscripts. Dee and his scrier (spirit medium) Edward Kelley lived in Bohemia for several