CHAPTER II 



METEOROLOGICAL OBSERVATIONS 



The rainfall has been measured at Eotliamsted since Fel)ruary 

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

 (7 feet 3'12 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 l^roadbalk 

 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 tlie ])right 

 sunshine have been made by means of a Campbell-Stokes 

 recorder. 



The average yearly rainfall as measured at Kothamsted 

 during the last fifty-one years, 1853-1903, is 28-Jl inches. 

 This is higher than the average in Hertfordshire (26'33). 



