Unpublished paper, 'Description of a quadrant for measuring horizontal angles by reflection' by W [William] Barnes Barnes describes the construction of his quadrant used to measure horizontal angles. The quadrant consists of a frame, an arch, a nonius, an index glass, an object glass, and a light vane. Includes a separate page of illustrations. The covering letter for this paper is found at AP/14/1/1. Subject: Scientific Instruments Received by the Royal Society on 7 August 1830. [1830]