Lorenzo, an Italian mathematician, was born at Bergamo in 1750. Intended for the church, he devoted his attention to the classical languages, and studied so successfully, that at the age of eighteen he was appointed professor of humanity in the university of his native city. From this situation he was promoted to the chair of Greek at Pavia. Chancing, however, in his twenty-seventh year, to take up a book on mathematics, he conceived so intense an enthusiasm for that science, that he forthwith renounced all other studies for its sake. His former success attended him in this new pursuit, and he was soon appointed professor of geometry in the college of Mariano at Bergamo. In 1796 he published at Milan his Geometry of the Compass, a work which secured for him the patronage of Bonaparte. Mascheroni, priest though he was, became a zealous promoter of the revolution that attended the invasion of Italy by the French. Accordingly he was elected a member of the legislative body of the Cisalpine Republic. In 1798 he was sent to Paris to study the French system of weights and measures, and to apply it to Italy. His zeal, however, in discharging this duty, was the cause of an illness which closed his career in July. 1800. Mascheroni's chief work, *The Geometry of the Compass*, was translated into French by M. Carette, Svo, Paris, 1798. (See Fifth Dissertation, § I.)