Mathematician, born in Ayrshire; abandoned his intention of entering the Church and devoted himself to the congenial study of mathematics, of which he became professor in the old university at Glasgow (1711), a position he held for 50 years; was the author of the well-known "Elements of Euclid," but is most celebrated as the first restorer of Euclid's lost treatise on "Porisms" (1687-1768).