Specification : The Self Recording Rain gauge (SRRG) consists of a rain water collector and a rainfall recording mechanism mounted on a base. The rainfall measuring unit consists of a float chamber containing light metal float and a siphen chamber. The chart is wound on rotating drum driven by mechanical clock which rotates 1 revolution in 25 hours. The float rises as per the rainfall & so the recording pen also rises plotting a line of on the chart. When the siphen chamber is filled completely, the water in it drains out completely called "Siphoning". When siphoning occurs, the pen fixed on the float rod falls to the zero mark on the chart and the gauge is ready to record rainfall again for 10 mm or 25 mm rainfall.