Unpublished paper and letter, 'Boussole angulaire de Leonelli' ['Leonelli's angular compass'] by Z [Zecchini] Leonelli Leonelli describes his invention of an angular compass, designed to aid ship captains in orienting themselves when they are unfamiliar with astronomical operations for determining longitude or when the sky is cloudy and therefore their marine watches are of little use. Includes an illustration of the compass. Followed by a cover letter from Leonelli to Augustus Frederick introducing this paper as well as AP/8/15-17. Subject: Navigation / Geodesy Written by Leonelli in Corfou [Corfu, Ionian Islands, Greece]. AP/8/15-18 were sent to the Royal Society together with the covering letter dated 24th April 1831, addressed to Augustus Frederick, Duke of Sussex, found at AP/8/18/3. 13 August 1831