AUDIFFREDI, GIOVANNI BATTISTA. - Dominican astronomer and bibliographer, b. at Saorgio (Nice) on 2 February 1714, d. at Rome on 4 July 1794. After several years of teaching, in 1759 he was elected prefect of the Biblioteca Casanatense in Rome, a post he held until his death. There, with very scant resources, he founded an astronomical cabinet, observing the transits of Mercury (1753 and 1756) and Venus (1761), studying eclipses and the motions of the moon (1754 and 1755), solar parallax (1765), and the theory of comets (1769).
Outstanding monuments of his activity as a bibliographer are the Catalogus Bibliothecae Casanatenensis, Rome, 1761–88 (up to the entry Leodegarius, 4 folio vols. and one fascicle), compiled according to new criteria that reveal his profound learning; the Catalogus historico-criticus Romanorum editionum saec. XV, Rome, 1783; and the Specimen historico-criticum editionum italicarum saec. XV, Rome, 1794; the latter works being of great value and usefulness.