METEOROLOGICAL OBSERVATIONS 



The rainfall has been measured at Ilothamsted since February 1853 in 

 a 5-inch funnel g;au<i;e, 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 

 euiploved since January 1881. The ground on which the gauges are 

 situated 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 deptlis — 20, 40, and 60 inches respectively — and inserting perfor- 

 ated 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. More recently a self-recording 

 soil thermometer has been set up. 



The average yearly rainfall as measured at Rothamsted during the 

 sixty years, 1853-1912, is 28*34 inches. 



Rain. 

 Inches. 



Mean 



Temper- 

 ature. 



70° 



60° 



50° 



40° 



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



Fig. 5.— Rainfall : Average of 60 years (1853-1912). 



Sunshine : Average of 20 years (1892, 1893, and 1895-1912). 

 Mean Temperature : Average of 35 years (1878-1912). 



