Its implicit value in the US system was originally one eighth of the Winchester bushel, which was a cylindrical measure of 18.5 inches (470 mm) in diameter and 8 inches (203 mm) in depth, which made the dry gallon an irrational number in cubic inches whose value to seven significant digits was 268.8025 cubic inches (4.404884 litres), or exact 9.252 × π cubic inches. Since the bushel was later defined to be exactly 2150.42 cubic inches, this figure became the exact value for the dry gallon (268.8025 cubic inches gives exactly 4.40488377086 L).[citation needed]