INTERNATIONAL SYSTEM OF UNITS OVERVIEW

摘要

There are almost 200 countries, but only three — the U.S., Myanmar and Liberia — have not adopted the International System of Units, the official metric system of weights and measures. Ancient Babylonian and Egyptian records, as well as the Bible, indicate that length first was measured with the forearm, hand or finger. Time was measured by the periods of the sun, moon and other heavenly bodies. Volume was measured with stones and seeds, which served as standards, and "carat" still is used as a unit of weight for diamonds and other gems.