FACTS I.V METEOROI.OGT. 31 



gathering with portentous blackness and armed with the fiery artillery of 

 heaven they come as the van guards of the approaching storm. Soon 

 these are succeeded by the great moving mass of cloud, of which they 

 were the precursors, which noiselessly and gently sheds down upon the 

 earth the choicest blessings of the skies. At other times after the rain 

 has, for some time, silently descended and refreshed the thirsty soil, as 

 if gathering up all their strength for one great effort, at once, amidst light- 

 nings, and thunders, and tempest, the clouds pour down upon the earth 

 their treasured waters, and then move off, leaving a clear and brilliant sky. 

 The thunder shower of summer belongs therefore to the regular system 

 of rains. If on the proper day the extended rain do not occur, there is 

 a strong probability that there will be thunder showers, which may be 

 regarded as the great rain in detached portions. But if that day pass 

 without either, then three or four days, or about seven days will pass 

 before the next showers may be expected to fall. These statements will 

 be confirmed by a reference to any correct register of the w^eather dur- 

 ing the summer. 



The circumstance that the thunder-cloud is generally found to move 

 eastward from some point near the west, whilst in the extended rain that 

 portion of the cloud which is in view moves either from the north east, 

 or some point near to it, or in the reverse direction, presents no difficulty 

 in classifying both under the same general head. The thunder-cloud 

 moves in a more elevated stratum of air than the lower portions of the 

 regular storm-cloud ; and that stratum is always moving from some west- 

 erly point of the horizon. Hence the upper portions of the extended 

 cloud, which extend up into this stratum, are also found to be moving in 

 the same direction. Whilst therefore the great mass of cloud is swept 

 in a vast curve from the West Indies over us towards the north east, the 

 upper portions are continually blown off towards the east, thus extend- 

 ing the storm on its eastern border. 



3. Another fact worthy of attention is, that in general, no particular 

 kind of weather, such as extreme heat or cold, storm or calm, can con- 

 tinue longer than ahout hco days. The change usually occurs on the third 

 day. Thus in winter when the weather is very stormy and cold, we may 

 look for a cessation of the storm, and a mitigation of the cold after the 

 lapse of forty-eight hours. Or in summer, when the heat is excessive, 

 the third day brings refreshing breezes, or cooling showers. In autumn, 

 or winter, or spring, a calm and cloudless daj- is usually followed in 

 twenty-four or thirty-six hours by rain or snow. 



Thus, then, amidst the greatest apparent irregularity and lawlessness, 

 we find that there is a beautiful regularity of succession in the phenomena 



