THEORY CONFIRMED BY PHENOMENA. bo 



hours (from ten to forty) before the beginning of the rain 

 or snow, and does not change till near the end : however, 

 it is believed that the upper clouds, during all this time, 

 continue to come from the south west. 



They certainly do so till they are concealed from view by 

 the lower clouds, which generally form a short time before 

 it begins to rain, and the moment the lower clouds break 

 away a little, near the end of the storm, the upper clouds 

 are seen moving in the same direction. Besides, I have 

 more than once got a peep through the lower clouds, during 

 the progress of a storm, and discovered thick, dense clouds 

 above, coming from the south west. 



I have also seen instances of a strong wind at the surface, 

 directly opposite to the motion of dense clouds above, which 

 were evidently not very high, from their great velocity, and 

 I afterwards learned that at the same moment there was a 

 very great rain about one hundred miles distant, in the di- 

 rection towards which the lower wind was blowing. The 

 extent, however, of these rains, I did not learn. It must 

 depend upon future and more extended observations, to 

 learn whether the outward motion of the air in the upper 

 part of the vortex, extends beyond the boundary to which 

 the inward motion of the air below reaches. 



90. On the ocean, it is known that these storms are at- 

 tended with immense swells, reaching beyond the agitation 

 of the atmosphere. This effect is probably much more de- 

 pendent on the diminished pressure of the atmosphere on 

 the ocean under the vortex, than on its horizontal velocity. 

 For a fall of three inches in the barometer will cause a rise 

 of the water of more than three feet to produce equilibrium, 

 and as the waters would move in all directions towards the 

 point of least pressure, their momentum would cause a rise 

 two or three times this quantity independent of the effect 

 caused by the friction of the air. How far the reciproca- 

 tion of this wave would extend I am not at able to say. I 

 9 



