EXAMINATION OF REID'S STORMS. 217 



sinking of the barometer under the cloud ; for the expansion 

 of the air under the cloud may be so great that the cold pro- 

 duced by that expansion may cause condensation of the 

 vapor in the air below the cloud down to the very ground. 

 I might go on to mention every phenomena connected with 

 storms, and show that they are all explained by the evolu- 

 tion of caloric in condensation of vapor ; but this is not my 

 present object. 



157. After making one or two other remarks, I shall pro- 

 ceed to give the particulars from which all these generaliza- 

 tions have been deduced. Mr. Redfield says, Dr. Mitchell 

 has recorded, as the result of the observation of laboring 

 people in New York, that when a haze or cirrus, which, 

 appearing at sunset, indicates the approach of a storrn, is 

 seen over Staten Island at S. W., or more southerly, the 

 storm of the succeeding day will blow from the north east ; 

 but if it appears over the Jersey shore of the Hudson, from 

 W. S. W. to N. W., then the storm is expected to blow from 

 the S. E. From this it would appear that the wind blows 

 towards the cloud of an approaching storm. 



What is the shape of storms generally ? or do they greatly 

 differ in shape ? 



Dr. Thomas, of Richmond, N. C., told me that he has 

 frequently seen storms of great length from N. E. to S. W., 

 and very narrow from S. E. to N. W., make their appearance 

 to the N. W. of where he lived, and approach him, coming 

 up, side foremost, against a S. E. wind, pass over in half an 

 hour, with the wind suddenly changing round to N. W. If 

 this should be found to be the shape of those storms at sea, 

 which Mr. Redfield says so often set in from S. E. and 

 change round to N. W., it would be in harmony with the 

 centripetal theory. But I forbear to hypothesise the day 

 is not far distant when the public will see the importance of 

 having facts on this subject ascertained by a system of wide 

 spread simultaneous observations. 



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