Geographical mile longitude at the equator is thus exactly 60 geographical miles. It was closely related to the nautical mile, which was originally determined as 1 minute of arc along a great circle of the Earth, but is nowadays defined as exactly 1852 metres. The US National Institute of Standards and Technology (NIST) notes that: "The international nautical mile of 1 852 meters (6 076.115 49...feet) was adopted effective July 1, 1954, for use in the United States. The value formerly used in the United States was 6 080.20 feet = 1 nautical (geographical or sea) mile." (6080.2 feet is 1853.24496 meters.)
Grain (unit) pre-1527 English weight system known as Tower weights, was a different sort of grain known as the "wheat grain". The Tower wheat grain was defined as exactly of a troy grain. Since the implementation of the international yard and pound agreement of 1 July 1959, the grain or troy grain (symbol: gr) measure has been defined in terms of units of mass in the International System of Units as precisely . is approximately . The unit formerly used by jewellers to measure pearls, diamonds, or other precious stones, called the jeweller's grain or pearl grain, is equal to of a