The variable

A history of raingauging

The first written reference to rainfall measurement was made by Kautilya in India in his book Arthasastra in the fourth century BC (Shamasastry 1915). The next reference comes from the first century AD in The Mishnah, which records 400 years of Jewish cultural and religious activities in Palestine (Danby 1933). But neither the Indian nor Palestinian measurements continued for long. They were just isolated events, doomed to be ignored and discontinued. There were to be no more quantitative hydrological or meteorological measurements for another 1000 years – a period in which scholars believed, or were forced to believe, that one turned to the sacred scriptures for answers to questions such as ‘Where do springs arise from?’. It was from China, around the year 1247, that the next known reference to quantitative rainfall measurement comes, and during the fifteenth century the practice of measuring rainfall was introduced into Korea, probably from China.

The first raingauge to be operated in Europe was made by the Italian Benedetto Castelli in 1639, a Benedictine monk and student of Galileo. Castelli measured rain only once, using a graduated glass cylinder about 12 cm in diameter and 23 cm deep. He does not seem to have considered doing this on a regular basis. In the 1660s Sir Christopher Wren made the first-known British gauge and later designed a second, which was probably the first ever that used a tipping bucket (Grew 1681).