Calendar Guldin, Paul Refutatio Elenchi Calendarii Gregoriana Setho Calvisio Conscripti, et Opera ... Libris Quatuor Calendarium Gregorianum ... de ratione Calendarii Ecclesiatici Christianorum, & Computi Hebraeorum. Mainz, Joannis Albin, 1616. 8 vols. 584 p. 8 vols. Gr.-8°. Pt. d. With Spanish edges and blind embossed fillets. Hs. R-title, full binding and three-page colour binding. (Clasps missing, with soiling and stains). Provenance: Ex Libris M. Hermanni Finsterling. Label of the Abbey Library of St. Gall. - Rare work on the reform of the Gregorian calendar by the Swiss mathematician and astronomer Paul Guldin (1577-1643). The work is a defence of the book "Elenchus Calendarii Gregoriani" by Seth Calvisius (1566-1615), who was also Guldin's teacher. - Guldin first learnt the craft of goldsmithing. In 1609, Guldin was sent to Rome to study mathematics under Clavius. He later became a professor of mathematics in Vienna. Guldin also had connections with the German astronomer Johannes Kelper. - Handwritten notes on the inside of the cover, as well as one page heavily browned with a few stains. Text still legible, otherwise in good condition. Contemp. vellum with Spanish edges and blind embossed fillets. handwritten spine title, full binding and three-sided colour binding. (Closing bands missing. With soiling and stains.) - Rare work on the reform of the Gregorian calendar by the Swiss mathematician and astronomer Paul Guldin (1577-1643). The work is a defence of the book "Elenchus Calendarii Gregoriani" by Seth Calvisius (1566-1615), who was also Guldin's teacher. - Guldin first learnt the craft of goldsmithing. In 1609, Guldin was sent to Rome to study mathematics under Clavius. He later became a professor of mathematics in Vienna. Guldin also had connections to the German astronomer Johannes Kelper. - Pages heavily browned with a few stains. Text still legible, otherwise in good condition.