BULLIALDUS (the latinized form of BOULLIAU, or BOULLAUD), ISMAEL, an eminent astronomer, was born at Loudun in France in 1605. He travelled in his youth for the sake of improvement; and afterwards published several works, among which are the following, viz. 1, De Natura Lucis, 1638, 8vo; 2, Philolaus, 1639, 4to; 3, Astronomia Philolaica, opus novum, in quo motus planetarum per novam et veram hypothesis demonstrantur, Loudun, 1645, folio; 4, Astronomiae Philolaicae Fundamenta clarius explicata et asserta adversus Zethi Wardi impugnationem, 1657, 4to; 5, De Lineis Spiralibus Demonstrationes, 1657, 4to; 6, Ad Astronomos Moneta duo, 1667; 7, Ptolemæi Tractatus de Judicandi Facultate, 1667, 4to; 8, Opus Novum ad Arithmetice Infinitorum, 1682, folio; and other works. He also wrote a piece or two upon geometry and arithmetic. In 1661 he paid Hevelius a visit at
Dantzic, for the sake of seeing his optical and astronomical apparatus. Afterwards he became a presbyter at Paris, and died there in 1694.