48 On the prevailing Storms of the Atlantic Coast. 
last and most dreaded portion of the receding storm.* A spirited 
and graphic description of this remarkable and well known crisis of | 
a hurricane, constitutes a leading feature in almost every well wrought 
description of a marine tempest. ; 
We have assumed that the leading storms of the northern and 
western Atlantic, and the American coast, originate in detached and 
gyrating portions of the northern margin of the trade winds, occa- 
sioned by the oblique obstruction, which is opposed by the islands to — 
the direct progress of this part of the trades, or to the falling in of the 
northerly and eddy wind from the American coast upon the trades, — 
or to these causes combined. Were it not for the fear of ranging — 
beyond the limits of established data, we might follow out this part — 
of the subject so far as to enquire after the probable influences which 
indicate or govern the succession of periods in which these aerial 
masses thus fall into a state of gyration, and the probable effect of 
this gyration upon each successive portion of the trade wind which _ 
may follow in the same course. If we venture on this ground, we 
would say that the most probable indication of the separations which _ 
we suppose to occur from this parallel of the trade, would be found _ 
in the diurnal influences to which they are exposed, these being — 
among the most powerful causes which mark the production of me- 
teorological phenomena, or, in other words, that such a portion of 
the passing atmosphere would be likely to become detached in one — 
body, as should arrive at, or pass a given meridian of the obstruction, © 
in the course of an entire day. The extent of this influence on 
atmosphere, if subject to a progressive rate of sixteen miles an hour, 
which is near the average advance of the storms in that region, — 
would be something short of four hundred miles from east to west, 
* To the southward of Newfoundland, shifts of wind are very common, and it fre- 
quently happens that, after blowing a gale upon one point of the compass, the wind 
suddenl “s shifts to the opposite point and blows eas strong. It has been knowD, — 
lon. 48° 55’, on or near the Banks, together with a whole fleet of West Indiamen, 
except five or six, they were all lying-to, with a hurricane from east south-east; 
wind shifted, without any warning, to north north-west and blew equally heavy, | 
and every ship lying-to under a square course foundered.—Purdy’s Memon r, 6th 
edition, pen ng 1829, corrected from Medical Repository. 
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