262 RAIN ON THE LINE 



The establishment of these rain gages was no 

 doubt undertaken with reference to the interest 

 of the canal proprietors. However, if they had 

 been influenced solely by a desire to promote 

 the science of Meteorology, they could scarcely 

 have devised places for Rain gages, better 

 adapted to that purpose. 



Four gages are placed within the compass of 

 12 miles distance. They include all the varieties 

 of situation that could be expected or desired 

 in that compass. 



Moss Lock gage has an extensive plane to 

 the west and south of it, from which quarters 

 the rains chiefly proceed. The currents of air 

 come to it steady and unruffled by obstructions. 

 There is no peculiar incentive to rain. Soon 

 after, the currents gradually ascend and get into a 

 colder region ; a portion of vapour is precipitated 

 in rain, and this cause of precipitation continues 

 to act till the air arrives at the summit, when 

 it is a maximum ; but the falls there are not a 

 maximum, because a current of air moving at 

 30 or 40 miles per hour, will not suffer the rain 

 to reach the ground at the same place where it is 

 formed : on the descent of the hill and probably 

 about the foot of it, the heaviest rain will fall. 



