[Footnote 68: _Nicolaus Coppernicus_ (Berlin, 1883-4; 3 vol.; Pt. I, Biography, Pt. II, Sources), by Dr. Leopold Prowe gives an exhaustive account of all the known details in regard to Copernicus collected from earlier biographers and tested most painstakingly by the documentary evidence Dr. Prowe and his fellow-workers unearthed during a lifetime devoted to this subject. (_Allgemeine Deutsche Biographie._) The manuscript authority Dr. Prowe cites (Prowe: I, 19-27 and footnotes), requires the double p in Copernicus's name, as Copernicus himself invariably used the two p's in the Latinized form _Coppernic_ without the termination _us_, and usually when this termination was added. Also official records and the letters from his friends usually give the double p; though the name is found in many variants--Koppernig, Copperinck, etc. His signatures in his books, his name in the letter he published in 1509, and the Latin form of it used by his friends all bear testimony to his use of the double p. But custom has for so many centuries sanctioned the simpler spelling, that it seems unwise not to conform in this instance to the time-honored usage.] [Footnote 69: Prowe: I, 85.] [Footnote 70: _Ency. Brit._: "Thorn."] [Footnote 71: Prowe: I, 47-53.] [Footnote 72: These facts would seem to justify the Poles today in claiming Copernicus as their fellow-countryman by right of his father's nationality and that of his native city. Dr. Prowe, however, claims him as a "Prussian" both because of his long residence in the Prussian-Polish bishopric of Ermeland, and because of Copernicus's own reference to Prussia as "unser lieber Vaterland." (Prowe: II, 197.)] [Footnote 73: Prowe: I, 73-82.]