James Gregory, 1638–75, Scottish mathematician. He invented a reflecting telescope (1661), which he described in his Optica promota (1663). In 1668 he became professor of mathematics at the Univ. of St. Andrews and, in 1674, professor of mathematics at the Univ. of Edinburgh. He originated a photometric mode of measuring the distance of stars and wrote Geometriae pars universalis (1668) and Exercitationes geometricae (1668).
"Gregory, James." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. (August 17, 2017). http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/gregory-james
"Gregory, James." The Columbia Encyclopedia, 6th ed.. . Retrieved August 17, 2017 from Encyclopedia.com: http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/gregory-james