Complex sentence: He was a member of the National Academy of Sciences, National Academy of Engineering, American Philosophical Society and several other professional societies and advisory boards and served as President (1993) and Chairman of the Board (1994) of the New York Academy of Sciences.
Split into simpler sentences: He was a member of the National Academy of Sciences, National Academy of Engineering, American Philosophical Society and several other professional societies and advisory boards. Harris served as president (1993) and chairman of the Board (1994) of the New York Academy of Sciences.