THE FORCING POWER OF RAIN. 22<g 



that the area of Great Britain and Ireland is about 

 120,000 square miles, and that the annual rainfall 

 averages about 25 inches, we see that the force-equi- 

 valent of the rainfall is enormous. All the coal 

 which could be raised from our English coal-mines in 

 thousands of years would not give out heat enough 

 to produce England's rain-supply for a single year. 

 When to this consideration we add the circumstance 

 that the force of rain produces bad as well as good 

 effects the former when the rain falls at undue 

 seasons or in an irregular manner, the latter only 

 when the rainfall is distributed in the usual manner 

 among the seasons we see that an important loss 

 accrues to a country in such exceptional years as the 

 present. 



There are few subjects more interesting than those 

 depending on the correlation of physical forces ; and 

 we may add that there are few the study of which 

 bears more largely on questions of agricultural and 

 commercial economy. It is only of late years that the 

 silent forces of nature forces continually in action, 

 but which are too apt to pass unnoticed and unrecog- 

 nised have taken their due place in scientific inquiry. 

 Strangely enough, the subject has been found to have 

 at once a most practical bearing on business relations, 

 and an aspect more strikingly poetical than any other 

 subject, perhaps, which men of science have ever taken 

 in hand to investigate. We see the ordinary processes 

 of nature, as they are termed, taking their place in 

 the workshop of modern wealth, and at the same time 



