The Metric System of Weights and Measures, destined to supplant all others, originated with Prince de Talleyrand, bishop of Autun, in 1790. Its almost universal adoption by civilized nations, its legality, though not compulsion, in England and the United States, and its adoption by the U. S. Pharmacopoeia of 1890, require that it should be understood alike by the physician and the druggist. Save in the English-speaking world it is the only system used for governmental, statistical, and scientific purposes, and in the arts and manufactures its value has long since been recognized. Its extreme simplicity, its uniformity, and its facility of computation render it far superior to any other system of Weights and Measures, and it is highly probable that in the near future it will prevail in the transactions of every-day life, as it has already acquired international importance, and is in fact referred to as the International System.

The starting-point is the unit of length, the meter (metre), which is the 1/4000000 part of the earth's circumference around the poles. From this apparently irrelevant measure of length the unit of capacity, or volume, the liter, was established, it being the cube of 1/10 of a meter. With equal simplicity and clearness, from the meter was derived the unit of weight, the gramme, which is the weight of that quantity of pure water at the maximum density, 40 C. (39.2 F.), which will fill the cube of 1/100 part of a meter (cubic centimeter).

The Metric is also known as the Decimal System, because its multiples and subdivisions are obtained by ten (Lat. decern). The prefixes denoting multiplication are of Greek derivation, and are usually spelled with a capital letter: Deka 10, Hecto 100, Kilo 1000, Myria 10,000. Division of the units is indicated by Latin prefixes, not capitalized: deci 1/10, centi 1/100, milli 1/1000 To distinguish readily one process from the other the word GILD has been aptly suggested as a mnemonic: