Richard Wright

He was in the voyage of the right honourable the earle of Cumberland in the yeare 1589. He 'devised the seaman's rings for the present finding out both of the variation of the needle and time of the day at one instant without any farther trouble of using any other instrument, and hath farther shewed how by the sun's point of the compasse (or magnetical azimuth) and altitude given by observation the variation may be found either mechanically with ruler and compasse or mathematically by the doctrine of triangles and arithmeticall calculation.'