The Nuttall Encyclopedia
Natural philosopher; invented a 5 ft. reflecting telescope, and a quadrant which bears his name, though the honour of the invention has been assigned to others, Newton included (1682-1744).
Wood, James, ed. Entry for 'Hadley, John'. The Nuttall Encyclopedia. https://www.studylight.org/encyclopedias/eng/nut/h/hadley-john.html. Frederick Warne & Co Ltd. London. 1900.