The Rain Gauge
The rain gauge is probably the oldest meteorological instrument.
The first measurements of rainfall amount were made in the orient, where reference was made in rainfall readings in a work called The Science of Politics by Chanakya, a minister of Chandragupta, who ruled India from 321 to 296 BC’
Rainfall measurements were also made in and around Palestine nearly 2000 years ago.
The son of King Sejong the Great, who reigned the Choson Dynasty from 1418 to 1445, is credited with inventing the first rain gauge. King Sejong sought ways to improve agricultural technology to provide his subjects with adequate food and clothing.
In improving agricultural technology, Sejong contributed to the sciences of astronomy and meteorology. He invented a calendar for the Korean people and ordered the development of accurate clocks. Droughts plagued the kingdom and King Sejong directed every village to measure the amount of rainfall.
His son, the crown prince, later called King Munjong, invented a rain gauge while measuring rainfall at the palace. Munjong decided that instead of digging into the earth to check rain levels, it would be better to use a standardized container. King Sejong sent a rain gauge to every village, and they were used as an official tool to measure the farmer’s potential harvest. Sejong also used these measurements to determine what the farmer’s land taxes should be.
Benedetto Custelli (1577 – 1643), a student of Galilio, is credited with originating the modern rain gauge in about 1639.
Robert Hooke, who discovered the law of elasticity and designed several meteorological instruments, made a rain gauge he called an ombrometer, derived from the Greek word ‘ombros’ and from which we get the word for an umbrella.
The basic design of the rain gauge has been the same for the past 350 years, but some have had square rather than round funnels and the sizes have varied.