The usefulness of mathematical learning explained and demonstrated [electronic resource] : Being mathematical lectures read in the publick schools at the University of Cambridge. By Isaac Barrow, D.D. professor of the mathematics, and master of Trinity-College, &c. to which is prefixed, the oratorical preface of our learned author, spoke before the university on his being elected lucasian professor of the mathematics. Translated by the Revd. Mr. John Kirkby, of Egremond in Cumberland.