MONTE, GUIDOBALDO, MARCHESE DEL (b. Pesaro, Italy, 11 January 1545; d. Montebaroccio, 6 January 1607), mechanics, mathematics, astronomy.

[He is known as Guidobaldo del Monte, although his signature reads Guidobaldo dal Monte. The form Guido Ubaldo (from the Latinized version) is often used, Ubaldo being taken incorrectly as the family name.]

Guidobaldo was born into a noble family in the territory of the dukes of Urbino. While at the University of Padua in 1564 he studied mathematics and befriended the poet Torquato Tasso. Later Guidobaldo served in campaigns against the Turks and in 1588 was appointed visitor general of the fortresses and cities of the grand duke of Tuscany. Soon afterward Guidobaldo retired to the family castle of Montebaroccio near Urbino, where he pursued his scientific studies until his death.

Guidobaldo was a prominent figure in the renaissance of the mathematical sciences. At Urbino he was a friend and pupil of Federico Commandino and an intimate of Bernardino Baldi, the mathematical historian. In 1588 Guidobaldo saw Commandino's Latin translation of Pappus through the press at Pesaro. The autograph transcript had initially been sent to the Venetian mathematician Barocius for publication; but Barocius, having refused to edit the work without making extensive changes, sent the manuscript to Guidobaldo, who published the text exactly as he found it. Concerning Pappus, Guidobaldo also corresponded with the Venetian senator Jacomo Contarini, who helped Guidobaldo secure an appointment at Padua for Galileo. Guidobaldo's correspondence with these and other friends is an important source for the history of the mathematics of the period.

Guidobaldo's first book, the Liber mechanicorum (1577), was regarded by contemporaries as the greatest work on statics since the Greeks. It was intended as a return to classical Archimedean models of rigorous mathematical proof and as a rejection of the “barbaric” medieval proofs of Jordanus de Nemore (revived by Tartaglia in his Quesiti of 1546), which mixed dynamic principles with mathematical analysis.

The Liber may be seen as a forceful argument that statics and dynamics are entirely separate sciences; hence no unified science of mechanics is possible. This attitude is evident in Guidobaldo's treatment of equilibrium in the simple machines, which he terms the case where the power sustains the weight. He stresses that a greater power is needed to move the weight than to sustain it and that the power which moves has a greater ratio to the weight moved than