NONIUS, PETER, in Spanish Nunex, a learned Portuguese, and one of the ablest mathematicians of the 16th century, was born at Alcaçer. He was preceptor to Don Henry, King Emmanuel's son, and taught the mathematics in the university of Coimbra. He published the following works, by which he gained great reputation: 1. De arte Navigandi. 2. Annotationes in theoriarum planetarum Purbachii; which are greatly esteemed. 3. A treatise De Crepusculis. 4. A treatise on Algebra. It is observed in Pireiere's dictionary, that Peter Nonius, in 1530, first invented the angles of 45 degrees made in every meridian, and that he called them rhumbs in his language, and calculated them by spherical triangles. Nonius died in 1577, aged 80.