CHAPTER II 



METEOROLOGICAL OBSERVATIONS 



THE rainfall has been measured at Eothamsted since February 

 1853 in a 5-inch funnel gauge and in a rectangular gauge 

 (7 feet 312 inches by 6 feet), having an area of one-thousandth 

 acre. 



In addition to these gauges, an 8-inch Board of Trade 

 gauge has been employed since January 1881. 



The ground on which the gauges are situated is 420 feet 

 above the sea-level; it adjoins the Barn Field (continuous 

 root crops), and is at a slightly lower level than the Broadbalk 

 and Hoos fields. 



The amount of water percolating through bare soil has 

 been measured since 1870 by means of three drain-gauges, 

 each having an area of one-thousandth acre. These were 

 constructed by undermining the soil at the desired depths 20, 

 40, and 60 inches respectively and inserting perforated iron 

 plates to support the soil. When this was completed, trenches 

 were cut round the blocks of soil, and these were then 

 isolated by means of brick and cement walls. The external 

 soil was then returned. The percolating water falls on to 

 zinc funnels, from which it passes to the measuring cylinders. 



Barometric and temperature records have been kept since 

 1873, and since July 1891 daily observations of the bright sun- 

 shine have been made by means of a Campbell- Stokes recorder. 



The average yearly rainfall as measured at Rothamsted 

 during the last sixty years, 1853-1912, is 28 '34 inches. 

 This is higher than the average in Hertfordshire (26 '29). 

 As regards years of exceptional rainfall, either low or high, 



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