326 Dove on the Law of Storms. 



of the temperate zones, when their course becomes deflected into 

 one almost at right angles to the former. Thus the storms of 

 the northern hemisphere move from S. E. to N. W., until they 

 have past to the north of the tropic of Cancer, when their course 

 becomes from S. W. to N. E. ; and, on the other hand, the 

 storms of the southern hemisphere, whose progress within the 

 tropics is from N. E. to S. W., take a new direction on entering 

 the southern temperate zone, and then move from N. W. to S. E. 



2. The breadth of the whirlwind, which increases very grad- 

 ually within the tropics, becomes suddenly greatly augmented at 

 the time when the path undergoes the above described flexure on 

 passing those limits. The chart of the West India hurricane of 

 the middle of August, 1837, in Colonel Reid's work, and that of 

 the Mauritius storm of March, 1809, in Berghau's atlas, are ex- 

 amples of these phenomena in either hemisphere. The course 

 of storms is further illustrated by a chart of Redfield's, in which 

 the tracts of ten are laid down. The paths of two of these 

 storms, which did not extend beyond the tropics, are rectilinear; 

 that of the 23rd of June, 1831, passes from Trinidad by Tobago 

 and Granada, through the middle of Yucatan to the neighbor- 

 hood of Vera Cruz ; that of the 12th of August, 1835, passing 

 from Antigua by Nevis, St. Thomas, St. Croix, Porto Rico, Hay- 

 ti, Matanzas, and Cuba, and thence to Texas. 



The courses of the eight storms which passed the boundaries 

 of the tropics were as follows : — 



The storm which ravaged Barbadoes on the night of the 10th 

 of August, 1831, reached Porto Rico on the 12th, the Keys, St. 

 Jago de Cuba on the 13th, Matanzas on the 14th, the Tortugas 

 on the 15th, the Gulf of Mexico on the 16th, and finally, Mobile, 

 Pensacola and New Orleans on the 17th, so that it had passed 

 over a space of 2,000 nautical miles in about 150 hours, or at the 

 rate of 13^ miles in one hour. Its direction before reaching the 

 tropic was N. 64° W. . 



The storm which began on the 17th of August, 1827, in the 

 neighborhood of Martinique, reached St. Martin and St. Thomas 

 on the 18th, passed to the northeast of Hayti on the 19th, reach- 

 ed Turks Island on the 20th, the Bahamas on the 2 1st and 22nd, 

 the coast of Florida and South Carolina on the 23rd and 24th, 

 Cape Hatteras on the 25th, Delaware on the 26th, Nantucket on 

 the 27th, Sable Island and Porpoise Bank on the 28th, having 



