Even with a drawing and a description by the inventor of how it works, the earliest accurate “recording rain gauge” looks complex.
Benjamin Bevan, a surveyor from Leighton Buzzard, Bedfordshire, helped to build canals, including the Grand Junction between London and Birmingham.
His gauge began recording on 1 January, 1817. The rain was collected in a cylinder. As it filled up, a float attached to a rod rose and drew a line with a pencil so that both the quantity of the rain and the speed with which it fell could be measured.
Bevan wrote to the Philosophical Magazine: “All the attention requisite is to wind up the timepiece from time to time, take off the sheet of paper from the cylinder and replace it with a fresh sheet marking the time on the paper when it was put on.”
But then he admits he missed 21 days of measuring the rate of rainfall that year by forgetting to wind up the mechanism or when the timepiece was faulty, but he managed eight complete months and to get the total rainfall for the year.
August was by far the wettest month with rain on 21 days totalling 4.35 inches. April was the driest, with only two days of rain and 0.07 of an inch.
His gauge proved popular, and by 1860 there were so many enthusiasts comparing the rainfall in different parts of the country that the British Rainfall Organisation was formed.
Forty years later there were more than 3,000 rainfall stations scattered across the country.
• This article was amended on 18 December 2015. An earlier version said Benjamin Bevan “also invented the slide rule”. Bevan wrote a treatise on the use of the slide rule, published in 1822, and it has been claimed that he designed a particular type of slide rule himself in 1813, but William Oughtred, who lived two centuries earlier, is generally recognised as the inventor of the instrument.
