470 



Bain/all in England. 



[Oct., 



It may be convenient here to recapitulate in a tabular form tbe 

 principal facts just established in connection with the three pluvial 

 elements of England and Wales, and which show that the rainfall 

 of a district depends on the wet-day rate of rain rather than on the 

 number of wet days. 









Max. 



Min. 



Mean. 



Average annual relative rainfall 



195 

 122 

 164 



63 



81 

 68 



100 



Average annual relative number of wet days 

 Average relative wet-day rate of rain 



100 

 100 







On taking the " wet" and " dry" counties as two distinct wholes, 

 their pluvial elements stand as below : — 





Actual. 



Relative. 





Wet. 



Dry. 



Wet. 



Dry. 



Annual average rainfall 



Annual average number of wet days . . 

 Annual average wet- day rate of rain . . 



49-14 in. 



185 days 



•27 in. 



28-68 in. 



160 days 



•18 in. 



171 

 116 

 150 



100 

 100 

 100 



The Influence of Height above the Ground on the Rainfall. — 

 It has long been known that at the same station a gauge on or near 

 the ground receives more rain than one higher above it. Dr. Dalton 

 stated, in 1802, that the ratio of the quantity of rain collected on 

 the top of St. John's steeple, Manchester, to that collected on the 

 ground in the vicinity, about 50 yards below, was in summer as 2 : 3 

 nearly, and in winter as 1 : 2 nearly.* 



Mr. Symons's 'British Kainfah" extends over the ten years be- 

 ginning with 1860 ; and at several of the stations whence he receives 

 returns there are two or more gauges at different heights above the 

 ground. Omitting all whose vertical distances are less than 10 feet, 

 and taking the highest and lowest only at the same station, there 

 were in Great Britain and Ireland 226 cases spread over the ten 

 years which are available for the discussion of the question imme- 

 diately under notice. 



The " vertical gauge-distances" varied from 10 feet to 99 '5 feet, 

 and averaged 40 * 5 feet. The total amount of rain received by all 

 the lower gauges was 6812*02 inches, and by the upper ones 

 5707 • 98 inches ; showing an actual defect of 1104 • 04 inches, or a 

 relative defect of 16 • 3 per cent. This, divided equally between the 

 226 cases, gives a total deficit of 4 ■ 885 inches each per year. Di- 

 viding, again, by the average gauge-distance, or difference of height 



* • Monthly Magazine,' vol. xiv., p. 5. 1802. 



