[2][a] Born in Port Hope, Ontario, he is credited with employing the first slide in an organized baseball game, while playing for the 1866 Rockford Forest Citys of the National Association of Base Ball Players.

[3] He was still playing for the Forrest Citys in 1869,[4] and was with them two years later when Rockford joined the first all-professional league, the National Association of Professional Base Ball Players.

[5] Rockford lasted just the one season in the Association, and Addy did not rejoin the league until 1873 when he joined the Philadelphia White Stockings.

[1] On January 20, 1874, the National Association's Judiciary Committee met to discuss, among other things, charges that Addy had joined the Boston Red Stockings before 60 days had elapsed since leaving the Philadelphia club.

At season's end, the Association folded and was replaced by National League, and Addy joined the Chicago White Stockings.