fortifications, and, from the school which thus grew up in his capital, there issued a series of military architects whose fame and services extended beyond the Alps. * * * * * The first of these whom we shall mention was FEDERIGO COMANDINO, born at Urbino, in 1509, of a noble family. His grandfather was secretary of Duke Federigo, whose last confidential instructions he received, when death surprised that veteran general in the fens of Ferrara. Baldi has claimed the invention of those bulwarks in fortification called _baluardi_ for his father, Gian Battista,[135] who built the walls at Urbino in the beginning of the sixteenth century. After a liberal education, Federigo passed several years at the court of Clement VII., nominally as a privy chamberlain, but really to amuse with learned disquisitions the Pontiff's leisure hours, on whose death he repaired to Padua, where he devoted ten years to the study of philosophy and medicine. Having graduated, he settled for clinical practice at Ferrara, but seems soon to have abandoned the healing art for mathematical research. He accompanied his sovereign, Guidobaldo II., to the camp at Verona when in the Venetian service, and, having gained his confidence by successfully treating him in a severe illness, he was selected to instruct him in astronomy and cosmography, as well as in military tactics and engineering. Soon, however, resuming his more abstruse studies, under the patronage of Cardinal Ranuccio Farnese, brother of Duchess Vittoria, he was carried by him to Rome, and introduced into the society of Annibale Caro, Fulvio Orsini, Baldassare Turrio, and Cardinal Cervini, the last of whom was cut off too quickly after his election as Marcellus II. to be able to benefit his friends. But for Comandino ambition offered few temptations, and courts had no charm. In studious retirement he devoted to the exact sciences the matured powers of a comprehensive and most retentive mind. He explored all that classical authors were known to have left on these subjects, and rendered again accessible much that lay forgotten among the rubbish of by-gone learning. He translated, and copiously edited, Ptolemy's treatise on the planisphere, which was published at Venice, in 1558, and, four years afterwards, gave to the world a work on the analemma, founded upon the same author's previous and imperfect discoveries. His labours were then transferred to the writings of Archimedes, several of which he printed for the first time, as well as the dissertations of Serenus and Apollonius upon conic sections, all with elaborate commentaries. [Footnote 135: This has also been imputed to Francesco di Giorgio, to Sanmichele, and to Bartolomeo Centogatti of Urbino.]