## SCHWENTER, Daniel.

# Deliciae Physico Mathematicae. Oder Mathemat und Philosophische Erquickstunden, Darinnen Sechshundert Drey und Sechsig, Schöne, Liebliche und Annehmliche Kunststücklein, Auffgaben und Fragen, auf; der Rechenkunst, Landtmessen, Perspectiv, Naturkündigung und andern Wissenschafften genomen, begriffen seindt, Wiesolche uf der andern seiten dieses blats ordentlich nacheinander verzeichnet worden: Allen Kunstliebenden zu Ehren, Nutz, Ergössung des Gemüths und sonderbahren Wolgefallen am tag gegeben Durch M. Danielem Schwenterum.

Nuremberg: Jeremiae Dumseis, 1636.

First edition of this early collection of mathematical puzzles, games and inventions, several of which are illustrated on the title page in small vignettes. The sixteen sections cover a wide range of subjects, from mathematics to optics and hydraulics. Leibniz read a copy of the book in his student days, his study of its many combinatorial problems leading to his first mathematical publication, the *Ars combinatoria* (1666), which formed the mathematical basis for his proposed ‘calculus of thought’.

As well as numerous problems in ‘recreational’ mathematics, Schwenter’s book describes several significant inventions. Perhaps the most notable of these is a fountain pen, which was made from two quills, one of which served as a reservoir for ink inside the other quill. The ink was sealed inside the quill with cork, and ink was squeezed through a small hole to the writing point. Although Schwenter did not invent the fountain pen, his is the first illustration of a working fountain pen in a printed work.

One original invention of Schwenter described in this book is the ‘scioptric ball’. This is a universal joint that allows a microscope, mounted on the ball, to be swivelled into any position. Its invention was inspired by Schwenter's studies of the human eye. The scioptric ball provided a firm anchor for a microscope or telescope while allowing the telescope to be swivelled in all directions in order to follow the course of an eclipse or for drawing panoramic views. It was in some ways the first wide-angle lens.

Schwenter’s Deliciae is sometimes described as a translation of Van Etten & Leurechon’s Récréations Mathématiques (first published in 1624), but Singmaster has pointed out that this is ‘quite wrong’. Schwenter does indeed consider some of the problems in Leurechon’s book (these are identified as “aus dem Frankosen”), but many of the problems in Deliciae were collected by Schwenter himself. The book proved extremely popular, and was expanded to three volumes by Georg Philip Harsdörffer (1651-53). This was for many years the most comprehensive work on the subject, and was reprinted in 1677 and 1692.

Professor of oriental languages and mathematics at the University of Altdorf, Daniel Schwenter was born at Nuremberg in 1595 and died on 19 January 1636, a few months before the publication of this, his second book. He was also the author of *Geometriae practicae novae*, which appeared in four parts from 1616 to 1627.

David Singmaster, Sources in Recreational Mathematics: An Annotated Bibliography (www.gotham corp.com/sources.htm) contains descriptions of several of the mathematical problems considered by Schwenter.

Small 4to: 189 x 151 mm. Pp. [xii], 574, [2]. Contemporary vellum over boards. Engraved titlepage, numerous illustrations and diagrams in the text. Some browning throughout, in all a very good copy.