METEOROLOGICAL OBSERVATIONS 



The rainfall has been measured at Rothamsted since February 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 situ- 

 ated is 420 feet above sea-level. 



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 sunshine have been made 

 by means of a Campbell-Stokes recorder. 



The average yearly rainfall as measured at Rothamsted during the fifty- 

 one years, 1853-1903, is 28*21 inches. 



Jan. Feb. Mar. April May June July Aug. Sept. Oct. Nov. Dec. 



Fig. 5.— Rainfall : Average of 51 years (1853-1903). 



Sunshine : Average of 11 years (1892, 1893, and 1895-1903). 

 Mean Temperature : Average of 26 years (1878-1903). 



