the parliamentary visitation of oxford that began in 1647 removed many senior academics from their positions, including (in november 1648) the savilian professors of geometry and astronomy. in 1649 wallis was appointed as savilian professor of geometry. wallis seems to have been chosen largely on political grounds (as perhaps had been his royalist predecessor peter turner, who despite his appointment to two professorships never published any mathematical works); while wallis was perhaps the nation's leading cryptographer and was part of an informal group of scientists that would later become the royal society, he had no particular reputation as a mathematician. nonetheless, wallis' appointment proved richly justified by his subsequent work during the 54 years he served as savilian professor.