Complex sentence: He did this after meeting the scientist Joseph Priestley (1733--1804) at his house in Birstall, Yorkshire on May 23,1771, who found out that plants make and absorb gases.
Split into simpler sentences: He did this after meeting the scientist Joseph Priestley (1733--1804) at his house in Birstall, Yorkshire on May 23,1771. Priestley had found out that plants make and absorb gases.