Camp was central to several more significant rule changes that came to define American football. In 1881, the field was reduced in size to its modern dimensions of 120 by 53 yards (109.7 by 48.8 meters). Several times in 1883, Camp tinkered with the scoring rules, finally arriving at four points for a touchdown, two points for kicks after touchdowns, two points for safeties, and five for field goals. Camp's innovations in the area of point scoring influenced rugby union's move to point scoring in 1890. In 1887, game time was set at two halves of 45 minutes each. Also in 1887, two paid officials—a referee and an umpire—were mandated for each game. A year later, the rules were changed to allow tackling below the waist, and in 1889, the officials were given whistles and stopwatches.