PEECOLATIOIf, AND ETAPORAXION". 09 



more will be drawn up to form cloud?. And perhaps the varying 

 Yt'looity of the wind will cause a still greater difference in the 

 amount of evaporation, and consequently in that of percolation. 

 But, one year with another, these causes of varying evaporation 

 will tend to equalize themselves, and variations in rainfall only 

 need be considered here. 



During the twelve calendar years 1880 to 1891 there has once 

 been, in 24 hours, a fall of rain exceeding 4 inches (17th July, 

 1890, at Moor Park, Rickmansworth, 4'19ins.); there has once 

 been a fall of from 3 J- to 4 inches (12th July, 1889, at High 

 Pown, Hitchin, 3*76 ins., and at Welwyn Rectory, and Fanhams 

 Hall, Ware, 3-50 ins.); there has twice been a fall of from 3 to 

 Sh inches (26th June, 1888, at Rothamsted, 3-24 ins., and 12th 

 July, 1889, at five stations in the county) ; there has twice been 

 a fall of from 2| to 3 inches (12th July, 1889, at seven stations, 

 and 17th July, 1890, at four) ; falls of from 2 to 2^ inches have 

 been recorded on eight occasions, at three stations each on the 

 average; falls of from li to 2 inches have been recorded on 

 twenty-five occasions (that is, about twice a year) at from three 

 to four stations each on the average ; and falls of from 1 inch to 1 g- 

 have been recorded on seventy-eight occasions (that is, from six 

 to seven times a year) at from four to five stations each on the 

 average. Falls of at least an inch were general over the county on 

 five occasions during the last twelve years, viz. : on 17th December, 

 1881; 10th September, 1885; 12th July, 1889; 17th July, 1890; 

 and 20th August, 1891. On two of these occasions, r2th July, 

 1889, and 17th July, 1890, the general fall in the county was at 

 least 2 inches. 



During the half-century ending 31st March, 1892, the greatest 

 fall of rain in the county in any month was 8*41 ins. at Tring 

 Yicarage in October, 1891, and the least was no rain at six stations 

 (out of thirty-six) in February, 1891. At the ten stations for 

 which rainfall tables are here given, the greatest fall in any 

 summer was 25-75 ins. at Rothamsted in 1879, and the least 

 was 6-05 at Hitchin in 1870; the greatest fall in any winter was 

 23-69 ins. at Gorhambury in 1882-83, and the least was 5-12 ins. 

 at Royston in 1879-80 ; the greatest fall in any year was 41*34 ins. 

 at Goi-hambury in 1882-83, and the least was 16-60 ins. at Royston 

 in 1870-71. Except in the yearly fall, the date of the extreme 

 anywhere has coincided with the date of the extreme in the county, 

 that is to say, the wettest and the driest summer, winter, and 

 month throughout the county have been the same as the wettest 

 and the driest summer, winter, and month at any one station. 

 But the year with the gi'eatest mean rainfall in the county was 

 1852-53, with 36*89 inches, and the year with the least mean 

 rainfall was 1854-55, with 19-33 inches. In the calendar years, 

 and including stations not represented in our ten rainfall tables, 

 the greatest fall of rain in any one year was 42*56 ins. at Moor 

 Park, Rickmansworth, in 1879, and the least was 15*79 ins. at 

 Barley, near Royston, in 1884. 



