This section is from the book "A Text-Book Of Materia Medica, Pharmacology And Therapeutics", by George F. Butler. Also available from Amazon: A text-book of materia medica, pharmacology and therapeutics.
The history of Weights and Measures affords a striking example of the incongruity resulting from the absence of a uniform standard of stable value to science, and must be regarded as the strongest argument in favor of the Metric, or Decimal, System.
An idea of the confusion prevailing under the old methods may be gained from an examination of their comparative units, by which we find that a pint is not a pound, an ounce not equal to a fluid-ounce, a drachm not equivalent to a fluidrachm, and a minim not commensurate with a grain. It was not until 1836 that the Secretary of the U. S. Treasury was directed by Congress to furnish each State in the Union with a complete set of revised standards, including the troypound of 5760 grains, from which the Apothecaries', or Troy, weight is derived, the latter term at present being applied only to the system used in weighing precious metals.
For commercial purposes the following Weights and Measures are employed:
Avoirdupois Weights: the Pound divided into 16 Ounces.
Liquid Measures: the "Wine Measure," of which the U. S. Gallon represents a volume of 231 cubic inches; each cubic inch of water at the maximum density (40 C.) being equivalent to 252.892 grains, the weight of a Gallon being therefore 58,418 grains. The Gallon is divided into 8 Pints (octarius), and the Pint is divided into 16 Fluidounces, each containing 8 Fluidrachms, or 480 Minims, the Fluidrachm containing 60 Minims. The signs used to designate these units are - m, denoting minim or minims; f3, fluidrachm or fluidrachms ; and fluidounce or fluidounces.