The current tanks are about four years old and are made of modern plastics following on from glass, iron and steel ones previously used. The funnel was completely restored in 1992 to its original hardwood and lead construction. At various times other smaller raingauges were used, both 5 and 8 inch funnel diameter. In 1948, the present 5 inch diameter gauge was installed which is now the Meteorological Office standard. At Rothamsted we have had a recording raingauge since 1921 which has always been of the natural syphon type.
Rain is collected in a float chamber and recorded on a daily chart on the clock drum.
This has the capability to record 10mm of rain before syphoning begins and the recording will then restart at the bottom of the chart. From this we can derive both rate and time of rainfall. The gauges were constructed by digging round and under the block of soil, placing perforated steel plates underneath at the required depth and bricking up the sides. The soil inside the gauges remained undisturbed throughout the construction process. He now had the ability to not only measure the rainfall, but also to find out how much of the rain was draining through the soil and, by analysis, how much nutrient was being lost.