NUNEZ, or NONIUS, PEDRO, an eminent Portuguese mathematician, was born at Alcacér do Sal in 1492. His attainments raised him to a high rank both as a teacher and as a writer in his own peculiar science. He became preceptor to Don Henry, son of King Emmanuel, and was installed in the mathematical chair at Coimbra. He also continued to publish, till his death in 1577, the following treatises:—De Arte Navigandi; Annotationes in Theorias Planetarum Purbachii; and De Crepusculis. It was in this last work that his device for subdividing the arcs of quadrants and other astronomical instruments was first promulgated. It consisted in describing within the same quadrant 45 concentric circles, and then dividing the outermost of these into 90 equal parts, the next into 89, the next into 88, and so on till the innermost, which is divided into 46. The nonius, as the instrument was called, was afterwards improved by others, until, in the hands of Pierre Vernier, it reached its present perfection, and received the
name of the vernier. A collection of the works of Nuñez was published at Basle in 1592.