640 Researches on the Gale and Hurricane QAugust, 



5th ditto, „ .. 87* .»• Blowing heavy from the East, showers, noon 



blowing very fresh and weather wild looking. 



6th ditto, ,, . . 80* . . A regular gale from the East with drizzling 



rain, noon gale increasing and more rain, 

 evening stormy and wet. 



7th ditto, ,, . . 80* . . Severe squalls through the night from the 



East with heavy and incessant rain, noon 

 blowing heavier, rained more Northerly, 

 evening raining very hard. 



8th ditto, ,, . . 80- . . Very wet morning, cleared up about nine. 



9th ditto, ,, . . 80- . . Gloomy morning with distant thunder. 



10th ditto, ,, .. 80' .. Heavy Squalls through the night, torrents of 



rain, cleared up at 8 a. m. noon close, calm 

 and sultry. 



My attention was drawn to this theory while endeavouring to trace 

 some barometric curve, and some relation between it and the magnetic 

 equator,* and withal some law which might theoretically account for 

 the paraboloidal course of the West Indian and American hurricanes, 

 as shown by Mr. Redfield and Col. Reid ; and the singular difference 

 shown by the track of our Hurricane led me to suppose that it might 

 perhaps move in the axis of the parabola ? Mr. Ravenshaw's letter 

 shortly afterwards gave much credit to these views, and subsequent 

 facts serve to justify our asserting that for this time at least it has 

 done so. 



If we describe, as I have done on the Map No. II, a great parabola, 

 one branch of which stretches towards Ceylon, and the other up to the 

 valley of the Ganges towards Agra, the vortex being towards Arracan, 

 and the axis in the line of the supposed track of the Hurricane; it will 

 be found that the focus of such a parabola falls in about lat. 19° 36' N. 

 long. 88° 10' E. which was about the centre of the Hurricane on 

 the 4th. These sort of lines are of course arbitrary, but still the coin- 

 cidence is novel and curious ; whether we look upon the whirls of the 

 Hurricane to have been produced by the mere dynamic action of the 

 streams of air, like the eddies within the bends of a river flowing 

 through a curved channel, or suppose that these vortices are Thermo- 

 electric Phenomena, produced by the sudden transfer of great volumes of 

 the caloric and moisture of the stream of air from the warm equatorial 

 regions to the colder ones toward and beyond the tropics. The re- 

 marks on the warmth of the weather in the logs, and the thermometrical 



* It may be worth remarking that while this hurricane seems to have travelled from 

 East to West or nearly parallel to the direction of the Magnetic Equator as laid down 

 by Biot, those of the West Indies seem for the most part to come from the South East- 

 ward, which is also there the direction of the plane of the Magnetic Equator. The 

 " Raleigh's" Hurricane in the China Seas seems too to have travelled in this 

 direction. 





