“The home team was shorthanded, Dalrymple’s injury of the day before placing him on the disabled list.” Chicago Tribune, May 4, 1881, p5
Previous earliest use (Dickson Baseball Dictionary, 3rd edition, 2009):
1ST USE. 1887. “Jerry Reardon the St. Louis boy who fractured his right leg while running bases here is still on the disabled list” (The Sporting News, June 11; Peter Morris).
