66 Rainfall, Natural Drainage, 



place in the distribution or quantity of rain in a district ; tliese 

 are only to be determined by comparing long series of obser- 

 vations, and we can only enter upon the discussion of them by 

 accumulating, reducing and comparing all the facts known on 

 the subject. And here lies the difficulty. Records exist, but 

 unfortunately they are by no means of equal value, nor do they 

 always admit of exact comparison. Referring to the best of 

 them, however, let me endeavour to state some of the results as 

 clearly and usefully as may be. 



The existing tabular statements of the amount of rainfall at 

 various stations in our own islands afford abundant matter for 

 consideration. Taking first the averages for ten well-observed 

 years, which more extended observations in a limited number 

 of stations warrant us in regarding as not far from a general 

 average, we shall find that whereas at one place, Bishops- 

 wearmouth in Durham, there fell on an average 16*91 inches 

 per annum during the period from 1st Jan., 1850, to 31 Dec, 

 1859, the average at Seathwaite in Cumberland during the 

 same time was 126'98 inches per annum, or about seven 

 and a half times as much. It is not difficult to explain this 

 difference by reference to the geographical position of the two 

 stations. Seathwaite receives the rain produced by the con- 

 densation of the warm moist winds from the Atlantic as they 

 are driven up the chilled and snow-clad sides of the Cumber- 

 land mountains. Bishops wearmouth, on the other hand, receives 

 the rain chiefly, if not solely, from winds already partially drained 

 by crossing the inountains and moors that lie between it and the 

 Atlantic. These are extreme cases. There are few parts of 

 Northern Europe where the average rainfall is below that of 

 Bishopswearmouth, and few places out of the tropics where it 

 exceeds that of Seathwaite. The results of extremely wet years 

 further heighten the contrast. Thus the average of the three 

 wet years, 1860-1862, at Seathwaite, was 164*94 inches, while at 

 Bishopswearmouth it amounted only to 21*66 inches, and during 

 the year 1862 when there fell 182'58 inches at Seathwaite, there 

 only fell 19*30 inches at Bishopswearmouth. 



There are two other stations, one at Coniston in Lancashire, 

 and the other at Torosay in the isle of Mull, in each of which 

 the rainfall occasionally amounts to 100 inches, but these are 

 all very extreme cases and due to local causes. 



To understand the rainfall of England, it will be convenient 

 to take the mean or average amount for ten years in certain 

 stations in different parts of the country. Thus, excluding the 

 stations at Seathwaite and Coniston as exceptional, we find 

 that the average of six stations situated in Lancashire and the 

 West Riding of Yorkshire, all on the west side of England, 



