Missionary, mathematician, and astronomer, born at Milan in 1583; died at Rome, 24 May, 1632. His family was one of good standing in Milan. He became a member of the Society of Jesus, 16 September, 1601; in 1616 he was sent from Macao with Father Marquez, S.J., as one of the first missionaries to Cochin-China. Here he stayed until 1622, being known under the name of Bruno. After his return he taught mathematics at Coimbra; in 1632 he entered the Cistercian Order, taking the name of Father Onofrio, and died the same year. His most important work "Relatione della nuova missione delli P.P. della Compagnia di Gesù al Regno della Cocincina" appeared at Rome in 1631 and was translated into French (Rennes, 1631), Dutch (Louvain, 1632), Latin and German Vienna, 1633), and English (London, 1633). It was also inserted in Churchill's "Collection of Voyages" (1704), II, 737-838, and in and Sprengel and Forster's "Neue Beitrage zur Volkerund Länderkunde" Leipzig, 1793), II, 27-110. The work was considered one of the best sources of information concerning Cochin-China on account of its excellent description of the physical, political, and ecclesiastical conditions of the country. The observations of Borrus on the magnetic variation of the compass appear to be of more importance, but unfortunately they have not yet been published. According to Kireher he drew up the first chart for the Atlantic and Indian Oceans showing the spots where the magnetic needle makes the same angles with themeridian; in this he is to be regarded as the forerunner of Halley. Borrus gives the explanation to the chart in a manuscript that belongs to theRoyal Academy at Lisbon. In another manuscript, now at Evora, "Tratada da arte de navegar pelo Cristovao Bruno", which bears on the same subject, he makes excellent suggestions, according to Allatius, as to a new method for determining the longitude at sea and also concerning improvements in sea-charts. Father Le Jeunehomme undertook a translation of the treatise into Latin. Philip of Spain, desiring to understand the nautical studies and inventions of Borrus, once summoned the latter from Coimbra to Madrid. Besides what has been already mentioned Borrus wrote, "Doctrina de Tribus Coelis, Aereo, Sydereo et Empeireo" (Lisbon, s. d.), which Pietro de Vale translated into Persian (Maius, Scriptor. vet, nova collect., IV, n. ix), and also some accounts of his travels for the Propaganda.

Allatius, Apes Urbanae (Rome, 1633), 66; Kircher, Magnes sive de arte magneticâ (Rome, 1641), 502; De Visch, Bibliotheteca scriptorum Sacr. Ord. Cisterciensis (Cologne, 1656) 71; Argelati, Biblioth. Scriptor. Mediolanesium (Milan, 1745), I, ii, 238; d'Avezac, Apercus historiques sur la boussole in Bullet. de la Soc. de Géogr. (Paris, 1860), XIX, 358; Carayon, Docum. inédits (Poitteirs, 1864), IV, 39; Von Humboltd, Kosmos (Stuttgart, 1869), IV, 171; Peschel-Ruge, Geschite der Erdkunde (2d ed., Munich, 1877) 726; Amat di S. Flillippo, Biographia dei viaggiatori italiani (2d ed., Rome, 1882), 375-377; Corvo, Roteiro de Lisbona a Goa por D. Joao de Castro (Lisbon, 1882), 393 sqq.; Backer-Sommervogel, Bibl. de la c. de J. (1890), I, 1821-22; VII, 1878; Hellmann, ed., Neudrucke ron Schriften und Kartenuber Meteorologie und Erdmagnetismus (Berlin, 1895), No. IV, 18.

Otto Hartig