Baseball books (non-fiction) from around 100 years ago, available as free eBooks (collected for my nephew): 

Reminiscenses and Historical Commentary

• Pitching in a Pinch; or, Baseball from the Inside (1912) by Christy Mathewson.  The New York Giants pitcher’s book full of behind-the-scenes stories about players and managers in the Big Leagues.  Includes stories about Ty Cobb and other greats of the time.  (Mathewson also authored a series of boy’s fiction books, such as Won in the Ninth and Pitcher Pollock.)

• A Ball Player’s Career (1900) by Adrian Constantine Anson – The manager and captain of the Chicago Baseball Club reminisces about growing up in Marshalltown, Iowa in the 1850’s and 1860’s and his baseball experiences in the latter half of the 1800’s.
• America’s National Game:  Historic Facts Concerning the Beginning, Evolution, Development, and Popularity of Base Ball, with Personal Reminiscences of its Vicissitudes, its Victories and its Votaries (1911) by A. G. Spaulding – Comprehensive history from the development of the game, pre-Civil War ball clubs, through to 1911, filled with historical photos and sketches.
• Sights around the World with the Base Ball Boys (1892) by Harry Clay Palmer – This book provides more detail of the 1889 round-the-world tour discussed by Adrian Anson, A. G. Spaulding, and Christy Mathews in the above accounts. It discusses “the most interesting sketches of the famous sites of the world as they were seen. . . ,” historic world geography through the eyes of 1880’s baseball.

Historical Statistics, Facts

• Spalding’s Official Baseball Guide – 1913 by John B. Foster – A magazine with a collection of articles on the state of baseball that year and commentary on the National League, the American League, and the 1912 World Series.  There are also earlier issues from 1889 and 1895.
• Baseball Guide and Record Book 1945 – Detailed statistics from the year, including photos, ballfield dimensions, etc.
• Baseball Cyclopedia: A Compact but Comprehensive Review of the History of the Naitonal Game (1922) by Ernest J. Lanigan – Sections on early baseball history; pennant winners; cities of the leading circuits; title holders, famous games, players, and feats; world series facts and figures; minor leagues; records of major league players
• Base Ball and Base Ball Players: A History of the National Game of America and Important Events Connected Therewith from its Origin down to the Present Time  (1912) by Elwood Andrew Roff

Fiction and Americana

• Casey at the Bat (1912)