After his playing career finished he was attending an
International League game and was asked to officiate this game between Toronto and Hamilton when the assigned umpire fell ill. He umpired with the International League for the and seasons, then began his Major League Baseball career umpiring American Association games in . He began the season in the
Western League, but was back in the majors by August 17, working for the
National League. He also officiated on July 13, 1896, when
Ed Delahanty become only the second player to hit four
home runs in one game. By the end of the season, he began to work the bases almost exclusively instead of calling games from behind the plate. Notably, Emslie and O'Day were the two most experienced umpires in Major League Baseball history at that point, with Emslie having worked nearly 2,500 games and O'Day nearly 1,700. Later, Emslie showed up at a Giants' practice with a rifle, placed a dime on the pitching mound and shot it from behind home plate, sending the coin spinning into the outfield. Reportedly, McGraw never again challenged his eyesight.
Other activities Emslie was also president of the Canadian Grand International Trap Shoot, notably in charge of a large meet in
St. Thomas, Ontario in December 1916. ==Post-career==