Venice: Bernardo Giunta & G.B. Ciotti, 1609.
First edition of the main astronomical work by one of the greatest influences on Galileo. “Guidobaldo was Galileo’s patron and friend for twenty years and was possibly the greatest single influence on the mechanics of Galileo.” (P. L. Rose in DSB). In this work, originally composed in the 1580s but published posthumously by his son, Guidobaldo deals with mathematical and observational astronomy and the improvement of astronomical instruments. “Guidobaldo helped to develop a number of mathematical instruments, including the proportional compass, the elliptical compass, and a device for dividing the circle into degrees, minutes, and seconds [described and illustrated in this work].” (DSB). “In general Guidobaldo’s attitude to mathematical instruments paralleled his attitude towards machines. Through these material devices, he felt, abstract mathematical truth could be made completely visible.” (Rose, The Italian Renaissance of Mathematics, p.224).
Guidobaldo del Monte (1545-1607) studied mathematics at Padua and later at Urbino. He became the friend and pupil of Frederico Commandino, whose translation of Pappus he edited and published. His “first book, the ‘Liber mechanicorum’ (1577), was regarded by contemporaries as the greatest work on statics since the Greeks. [And his ‘Perspectivae libri sex’ (1600)] the best Renaissance study of perspective …Guidobaldo was Galileo’s patron and friend for twenty years and was possibly the greatest single influence on the mechanics of Galileo. In addition to giving Galileo advice on statics, Guidobaldo discussed projectile motion with him, and both scientists reportedly conducted experiments together on the trajectories of cannonballs. In Guidobaldo’s notebook (Paris MS 10246), written before 1607, it is asserted that projectiles follow parabolic paths; that this path is similar to the inverted parabola (actually a catenary) which is formed by the slack of a rope held horizontally; and that an inked ball that is rolled sideways over a near perpendicular plane will mark out such a parabola. Remarkably the same two examples are cited by Galileo at the end of the Two New Sciences, although only as postscripts to his main proof—which is based on the law of free fall—of the parabolic trajectory.” (DSB).Ricardi I 180; Houzeau & Lancaster 2912.
Folio (232 x210 mm), ff  128 (numerous mispaginations but fully complete); with large engraved celestial sphere on title and numerous woodcut diagrams in text; slight water stain on outer margin of title and the next 12 leaves; a fine copy in contemporary stiff vellum.