632 MR MILNE ON A REMARKABLE OSCILLATION OF THE SEA. 



it commenced about 2 P.M., with the wind at east, and in about six hours ended 

 with the wind at west. 



At Newcastle, which was to the eastward of the centre, though not so much 

 as Greenwich, the storm began with the wind at SE. by S., and ended with the 

 wind at NW. by W., in about eighteen hours. 



So, also, at Mackerston, the scud aloft was seen successively to be moving 

 from the SSE., S., SSW., SW., and W. 



These indications are all reconcileable, on the supposition that the gale in 

 question consisted of currents revolving from right to left. 



This inference is confirmed by the direction of the wind at Bristol, which, 

 on the 5th July, is stated to have been from the north. This is easily explained, 

 on the supposition that the centre of the storm pursued a track to the east of 

 Bristol, which, from other circumstances, it is probable was the case. 



c. There are facts of a different description, which lead to the same con- 

 clusion. 



The sudden and prodigious reduction of temperature in those parts traversed 

 by the centre of the storm, shews that, by some means, cold air was drawn down 

 to the surface of the earth ; and in no way would this be so naturally effected as 

 by a whirling storm, producing a rarefaction of the air in its central parts. Hence, 

 in those parts, the quantity and size of the hailstones which fell, and the sudden 

 depression of the barometer (in one place to the extent of a whole inch), during 

 the passage of the storm. 



The condition of the atmosphere in different places immediately before the 

 storm, suggests some interesting considerations, as to the mode in which the elec- 

 trical equilibrium was so violently disturbed. But it would be irrelevant, in this 

 paper, to enter on that path. It may be simply remarked, that in Scotland, 

 for some days before, there had prevailed a cold and parching wind from the NE., 

 whilst, in the south 1 of England, the temperature ranged about 80. When these 

 two aerial currents, so different in all respects, came into contact, a violent dis- 

 turbance was the necessary consequence. In the first place, an eddy or vortex 

 would be formed, which would move to the northward, by the greater force of 

 the SW. wind ; and if this current, as is probable, flowed on the right hand of 

 the other (looking to the Pole), the whirl would be from right to left. Then, the 

 sudden condensation of the warm vapour into rain and hail, would sufficiently 

 explain the various electrical phenomena which accompanied the storm in its pro- 

 gress northward. 



Without dwelling on these topics, I now resume the primary subject of in- 

 quiry, viz., the cause of the oscillation of the sea on the 5th July. This phe- 



1 At Brighton, the 5th July was the warmest day of the summer, the thermometer having stood 

 at 78 in the shade. But at night it sunk down to 



