NONIUS, PETER, in Spanish Nunez, a learned Portuguese, and one of the most able mathematicians of the sixteenth century, was born at Alcazar. He was preceptor to Don Henry, son of Emmanuel, and taught mathematics in the university of Coimbra. He published the following works, by which he gained great reputation, viz. 1. De Arte Navigandi; 2. Annotationes in Theoria Planetarum Purbachii, which are greatly esteemed; 3. A treatise De Crepusculis; 4. A treatise on Algebra. It is observed in Furetierre'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 eighty.