Complex sentence: Aaron Arrowsmith (1750-1823) was an English geographer and member of the Arrowsmith family of geographers, immigrated to London from Winston in Durham when about twenty years of age, and was employed by John Gary, the engraver.
Split into simpler sentences: Aaron Arrowsmith (1750-1823) was an English geographer and member of the Arrowsmith family of geographers. He immigrated to London from Winston, England in Durham, England when about twenty years of age, and was employed by John Gary, the engraver.