(Peter), in Spanish Nunez, a learned Portuguese, and one of the ablest mathematicians of the 16th century, was born at Alcacer. 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 theorias planetarum Purbachii; which are greatly esteemed. 3. A treatise De Crepusculis. 4. A treatise on algebra. It is observed in Furetiere'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.

name which was not many years ago given to the common device for subdividing the arcs of quadrants and other astronomical instruments, from the persuasion that it was invented by Nonius or Nunez, of whom some account has been given in the preceding article. The generality of astronomers of the present age, transferring the honour of the invention from Nunez to Peter Vernier, a native of Franche Comte, have called this method of division by his name. (See Vernier.) Mr Adams, however, in his Geometrical and Geographical Essays, has lately shown that Clevius the Jesuit may dilute the invention with them both. The truth seems to be, that Nunez started the idea, Clevius improved it, and Vernier carried it to its present state of perfection. The method of Nunez, described in his treatise De Crepusculis, printed at Lisbon 1542, consists in describing within the same quadrant 45 concentric circles, dividing the outermost into 90 equal parts, the next within into 89, the next into 88, &c. till the innermost was divided into 46 only. On a quadrant thus divided the plumb line or index must cross one or other of the circles very near a point of division; whence, by computation, the degrees and minutes of the arch might be easily ascertained. This method is also described by Nunez in his treatise *De arte aquae ratione navigandi*, where he would fain persuade himself, that it was not unknown to Ptolemy. But as the degrees are thus divided very unequally, and as it is very difficult to attain exactness in the division, especially when the numbers into which the arches are to be divided are incommensurate (of which there are no less than nine), the method of diagonals, first published by Thomas Digges Esq; in a treatise entitled *Ala seu scula mathematica*, printed at London in 1573, and said to be invented by one Richard Chenefer, was substituted in its room. Nonius's method was, however, improved at different times and by different persons; and it must be acknowledged, that if Vernier saw either the original or any of the improvements (and there can be little doubt of his having seen them all), his merit is only that of having applied to an useful practical purpose the speculative invention of another person.

(Marcellus), a grammarian and peripatetic philosopher, born at Tivoli, wrote a treatise, intitled *De proprietate verborum*. This author is only valuable for his giving fragments of ancient authors that are nowhere else to be found. The above treatise was printed at Paris in 1614, with notes.