Complex sentence: Stephen Vanderburgh Harkness (November 18,1818--March 6,1888) was an American businessman from Cleveland, Ohio, who invested as a silent partner with oil titan John D. Rockefeller, Sr. in the founding of Standard Oil.
Split into simpler sentences: Stephen Vanderburgh Harkness (November 18,1818--March 6,1888) was an American businessman based in Cleveland, Ohio. He invested as a silent partner with John D. Rockefeller, Sr. in the founding of Standard Oil.