Among the names distinguished in Urbino for mathematical talent, that of PACIOTTI was conspicuous. Jacopo Paciotti, who held several situations of trust under the two first Dukes of the Rovere dynasty, was father of three sons, all eminent proficients in the exact sciences. Felice was one of those commissioned to rectify the Gregorian Kalendar, and invented an instrument for constructing dial-plates. Orazio became a military engineer, and erected fortresses for the States of the Church, for Savoy, and for Lucca, with such reputation that his services were sought for Poland and for the Emperor Rudolph. But the most remarkable of the family was Francesco,[*138] who, after enjoying a liberal education, and thoroughly grounding himself in architecture under Girolamo Genga, went to Rome, where, in 1550,[*139] he was named engineer-in-chief by Julius III. Next year, he was employed to fortify Ancona against the dreaded descents of the Turk; but, leaving this undertaking to be completed by Fontana, he passed in 1551, to the service of the Farnesi, and thence to that of Emanuel Duke of Savoy, with 60 scudi of monthly pay. He soon afterwards published a plan of Rome; but his attention was chiefly devoted to military architecture, in which his reputation rapidly spread. In 1558, he was employed by Philip II. to survey, and report upon, the principal defences of the Low Countries, for which he was remunerated with 6000 scudi, and a massive gold chain. [Footnote *138: Cf. MADIAI, _Il Giornale di Francesco Paciotti da Urbino_ in _Arch. St. per le Marche e per l'Umbria_, vol. III., p. 48 _et seq._] [Footnote *139: This is the year in which the journal begins. In 1551 he tells us he left the service of the Pope to enter that of the Duke of Parma.]