Rule 1.05

Rule 1.05

Home base shall be marked by a five-sided slab of whitened rubber. It shall be a 17-inch square with two of the corners removed so that one edge is 17 inches long, two adjacent sides are 8½ inches and the remaining two sides are 12 inches and set at an angle to make a point. It shall be set in the ground with the point at the intersection of the lines extending from home base to first base and to third base; with the 17-inch edge facing the pitcher’s plate, and the two 12-inch edges coinciding with the first and third base lines. The top edges of home base shall be beveled and the base shall be fixed in the ground level with the ground surface. (See drawing D in Diagram 2.)


DISCUSSION
The terms "home base" and "home plate" are used interchangeably within the rulebook. In the early days of the game, both the batters plate and pitcher's plate were "marked by a flat circular iron plate, painted or enameled white." Only later did they obtain their angular shapes, but the term "plate" survives in the rulebook and in common baseball vernacular.

The rule book is a little ambiguous whether the beveled part of home base is actually part of home base. The beveled area is part of the ubiquitous black border that surrounds home base. However, the rule book is clear that the front edge of home base is 17" wide, and that will not include the black beveled edge upon measurement. Since the base is recessed into the ground, the black beveled edging should be (mostly) covered by dirt.

A dispute over whether the black beveled edging around home plate is part of the plate erupted when Lou Brock attempted to score during the 1968 World Series. Brock was called out by Umpire Doug Harvey when Harvey ruled Brock did not touch the plate. Brock contended that he touched the black edging and should be called safe.

Here is a news story about the controversy:
http://news.google.com/newspapers?nid=799&dat=19690425&id=6kIvAAAAIBAJ&sjid=H0gDAAAAIBAJ&pg=7080,1454662