an adaptation to the accumulating observational evidence in favor of Johannes Kepler's elliptical celestial mechanics: it incorporated elliptical orbits into the geo-heliocentric Tychonic theory. Riccioli accepted Kepler's ideas, but remained opposed to the heliocentric theory. Indeed, following the dispute with Angeli, Riccioli's attitude toward heliocentrism hardened. Other work Between 1644 and 1656, Riccioli was occupied by topographical measurements, working with Grimaldi, determining values for the circumference of Earth and the ratio of water to land. Defects of method, however, gave a less accurate value for degrees of arc of the meridian than Snellius had achieved a few years earlier. Snellius had been mistaken by approximately 4,000 meters; but Riccioli was more than 10,000 meters in error. Riccioli had come up with 373,000 pedes despite the fact that references to a Roman degree in antiquity had always been 75 milliaria or 375,000 pedes. He is often credited with being one of the first to telescopically observe the star Mizar and note that it was a double star; however, Castelli and Galileo observed it much earlier. In the words of Alfredo Dinis, Riccioli enjoyed great prestige and great opposition, both in Italy and abroad, not only as a man of encyclopedic knowledge but also as someone who could understand and discuss all the relevant issues in cosmology, observational astronomy, and geography of the time. Selected works Riccioli's works are in Latin. Astronomy Geographicae crucis fabrica et usus ad repraesentandam ... omnem dierum noctiumque ortuum solis et occasum (Ferroni: 1643) (Map of the world from Gallica) Almagestum novum astronomiam veterem novamque complectens observationibus aliorum et propriis novisque theorematibus, problematibus ac tabulis promotam (Vol. I–III, 1651) (Or: Volume 1 : ; ) , Bologna, 1661 . 2nd ed., Venice, 1672. Astronomia reformata (Vol. I–II, 1665) : Observations, hypotheses and explanations : Directions for use, and the 102 tables Vindiciae calendarii Gregoriani adversus Franciscum Leveram (1666) Apologia R.P. Io. Bapt. Riccioli Societatis Iesu pro argumento physicomathematico contra systema Copernicanum (1669) Chronologiae reformatae et ad certas conclusiones redactae ... (Vol. I–IV, 1669) , , & tomus quartus Tabula latitudinum et longitudinum (1689) Theology . Bologna, 1667, Immunitas ab errore tam speculativo quam practico definitionum s. Sedis apostolicae in canonizatione sanctorum, in festorum ecclesiasticorum institutione et in decisione dogmatum, quae in verbo Dei scripto, traditove implicite tantum continentur, aut ex alterutro sufficienter deducuntur, Bologna, 1668 (Listed in the Index Librorum Prohibitorum in 1669) De distinctionibus entium in