High Quality Content by WIKIPEDIA articles! The Joseph Priestley House was the American home of 18th-century British theologian, Dissenting clergyman, natural philosopher (and discoverer of oxygen), educator, and political theorist Joseph Priestley (1733–1804) from 1798 until his death. Located in Northumberland, Pennsylvania, the house, which was designed by Priestley`s wife Mary, is Georgian with Federalist accents. The Pennsylvania Historical and Museum Commission (PHMC) operated it as a museum dedicated to Joseph Priestley from 1970 to August 2009, when it closed due to low visitation and budget cuts. The house reopened in October 2009, still owned by the PHMC but operated by the Friends of Joseph Priestley House (FJPH).