DIGGES (Thomas), only son of Leonard Digges, after a liberal school education, went and studied for some time at Oxford; and by the improvements which he made there, and the instructions of his learned father, became one of the greatest mathematicians of his age. When Queen Elizabeth sent some forces to assist the oppressed inhabitants of the Netherlands, Digges was appointed muster master-general of them; by which he had an opportunity of becoming skilled in the art of
war. Besides revising, correcting, and enlarging some pieces of his father's already mentioned, he wrote and published the following learned works himself: namely, 1. "A sixe scale Mathematica; or, Mathematical Wings or Ladders, 1573," 4to. This book contains several demonstrations for finding the parallaxes of any comet, or other celestial body, with a correction of the errors in the use of the radius astronomicus. 2. "An arithmetical military Treatise, containing so much of Arithmetic as is necessary towards military Discipline, 1579," 4to. 3. "A geometrical Treatise, named Stratioticos, requisite for the perfection of soldiers, 1579," 4to. This was begun by his father, but finished by himself. They were both reprinted together in 1590, with several amendments and additions, under this title, "An arithmetical warlike Treatise, named Stratioticos, compendiously teaching the science of numbers, as well in fractions as integers, and so much of the rules and equations algebraical, and art of numbers coessential, as are requisite for the profession of a souldier. Together with the moderne militaire discipline, offices, laws, and orders in every well-governed campe and armie, inviolably to be observed." At the end of this work there are two pieces; the first intitled, "A brieve and true report of the proceedings of the Earle of Leycester, for the reliefe of the towne of Slace, from his arrival at Vlissing, about the end of June 1587, untill the surrendre thereof 26 Juli next ensuing. Whereby it shall plainlie appear, his Excellencie was not in anie fault for the losse of that towne." The second, "A brieve discourse what orders were best for repulsing of foraine forces, if at any time they should invade us by sea in Kent, or elsewhere." 4. "A perfect description of the celestial orbs, according to the most ancient doctrine of the Pythagoreans, &c." This was placed at the end of his father's "Prognostication everlasting, &c." printed in 1592, 4to. 5. "A humble motive for association to maintain the religion established, 1621," 8vo. To which is added, his "Letter to the same purpose to the Archbishops and Bishops of England." 6. "England's Defence: or, a Treatise concerning Invasion." This is a tract of the same nature with that printed at the end of his Stratioticos, and called, "A brieve Discourse, &c." It was written in 1599, but not published till 1686. 7. "A Letter printed before Dr John Dee's Parallactic Commentationis praeclarique nucleus quidam, 1573," 4to. Besides these and his Nova Corpora, he had by him several mathematical treatises ready for the press; which, by reason of law-suits and other avocations, he was hindered from publishing. He died in 1595, but we know not at what age.