On the Courses of Hurricanes. 205 



lence will pertain to only one of the phases which the storm 

 presents, in its regular course over such locahty. This may usu- 

 ally be accounted for, by the interposition of land within the 

 course of the immediate circuit which the wind is found to pur- 

 sue') and this result is perhaps most obviously exhibited in the 

 South Atlantic or in the Southern Ocean, near the Cape of Good 

 Hope, where the barometric column, not unfrequently, subsides 

 and commences rising, before the full violence of the gale takes 

 effect. The baromet-er, however, appears always to indicate the 

 true extent and path of these whirlwind storms ; and I have 

 found no good grounds to infer, that a hurricane contracts in the 

 width of its path, while sweeping upon the surface of an open sea. 



7. Another source of apparent irregularity in the changes of 

 wind in these storms, arises from the interposition of one storm 

 upon the path of another, in their passage through the temperate 

 latitudes. Col. Reid has shown something like this in the hurri- 

 cane which overtook the Castries, August 24th, 1837, which was 

 evidently impinging upon the path of the great hurricane which 

 had previously swept along the American coast. That of the 

 Castries appears to have pursued a course similar to the hurricane 

 of October 1st, 1830, as delineated on my first pubhshed chart; 

 thus advancing, by a shorter course, into the path of the larger 

 hurricane, and probably with a greater progressive velocity. Col. 

 Reid justly urges the influence of these causes in producing the 

 irregular winds of the higher latitudes. Of the influence of such 

 interposition in apparently arresting or modifymg the regular de- 

 velopment of a storm while in progress, I have for many years 

 been convinced ; but it is due to Mr. Espy, of Philadelphia, to 

 mention, that, so far as I know, he was the first to publish the 

 suggestion.* 



In tracing out the path of hurricanes, we justly discard all 

 theory ; and as the information obtained of their course and ex- 

 tent is necessarily limited, and is acquired at different and uncer- 

 tain periods, our delineations are, therefore, necessarily subject to 

 minor errors and to subsequent corrections. Such corrections, I 

 have ever found to be in favor of the uniform rotation and reg- 

 ular course of progression, which have formerly been described. 

 It is probable, therefore, that the narrowed track, and somewhat 



* Journal of the Franklin Institute, Vol. xvni, October, 1836, p. 239. 



