This is an original George Grantham Bain glass plate negative of Home Run Baker at the Polo Grounds in New York during the 1911 World Series.

We know it is the World Series as the dugout background matches known images of the Polo Grounds which was built in 1911. Baker’s A’s played the New York Giants there during the 1911 World Series. Baker is wearing an upturned collar and the A’s switched to collarless jerseys in 1913 when the A’s played there again. Also we know it is 1911 based on a known photo of Baker in March 1912 during Spring Training; note the cap match down to the distinctive indention at the upper left of the cap and the wavy curve of the bill.