Ancient peoples standardized hundreds of different weights and measures to meet the needs of their civilizations.
The grain of wheat taken from the middle of the ear was probably the first standard weight element. Of the adopted systems, one of them spread throughout Europe and today is still used by the English-speaking countries, after minor modifications: it is the trading system called "AV", French word meaning "heavy goods". Its units are:
- grain (gr)
- drachma (dr)
- ounce (oz)
- pound (lb)
- yard (cwt)
- ton (t)
Regarding time, although he could not hold or store it, man could measure it by recording the repetitions of periodic phenomena. Any family event served to mark the time: the period between sunrise, the succession of the full moons, or the spring. You should know that, like the ancients, Indians counted the years by winters or summers, the months by moons and the days by suns. Such calculations were not very accurate. Bright hours between sunrise and sunset vary greatly during the year. The period from one full moon to another remained constant. Men soon realized this fact and concluded that the most accurate way of measuring time was based on the periodicity of events in celestial bodies.
Our year is the period of time when the earth makes its translational motion around the sun. It is sometimes called the astronomical, equinoctial, natural or solar year. Scientists usually call it a tropic year and have 365 days, 5 hours, 48 minutes, 45 seconds and 7 tenths. As in the calendar we consider only 365 days, every four years, the hours and minutes left are gathered, forming one more day, which appears in the leap year.
The month was the first accurate measure of time. It was calculated from one full moon to another and was exactly 29 and a half days old. However, dividing the year into lunar months yielded 12 months and a surplus of 11 days. There was no exact relationship between the year calculated by the earth's translation around the sun and the lunar month. This caused confusion when starting a new month. Other attempts at divisions regarding natural phenomena were refuted for the same reason. Julius Caesar, in 46 BC, abolished the lunar year and adopted the 365-day solar year, one day more every four years. The months were roughly based on lunar months, but of different duration. Roman emperors used to subtract days from a few months to add them to others, their favorites. The 7-day week has no exact relationship to the celestial bodies and their movements, although the division of the month into four weeks originates in the divisions representing the four phases of the moon.
The day is established by the period of rotation of the earth around its axis. The hour is the twenty-fourth part of the day, but there is no relationship between natural phenomena and one-hour repetitions: the division was done arbitrarily and for convenience. The sundial, which consisted of a stick sticking out of the ground in the center of a circle, was the first instrument for measuring the time interval. One hour has 60 minutes and this one 60 seconds. This division was made by the ancient Babylonians (circa 2000 BC), who adopted a sexagesimal base system, as they had already divided the circle into base 60, a criterion that we have upheld to this day.