The Keystone Cops were a regular feature in Mack Sennett's silent Keystone comedies. Their heyday was between 1912 and 1917. The ensemble that played the comical police force changed from film to film. (Many were per diem actors who remain unknown to this day.) Ford Sterling usually played the police chief. In this still photo silent screen buffs will recognize Roscoe Arbuckle and Edgar Kennedy.