The Hind's Triple Play

The first unassisted triple play makes for a good story, but an truse question of rules interpretation does not. Jack burdock was batting when he hit a south line drive that would later be called a texas leaguer over the short stop's head. Paul hines, playing shallow center field, made a shoe string catch and ran to third base. By this time jack manning and ezra sutton were both at home. Under the modern rules, this clearly would not be unassisted. But baseball hasn't passed out all knowledge about what happened in 18 78.