Dove on the Law of Storms. 337 



it must flow southward in some other quarter, and according to 

 the rotation of the whirlwind, this might be expected to be in 

 America. In effect, the thermometer at Salem in Massachusetts, 

 in the latitude of Rome, stood — 10°.2 R. on the 24th of Decem- 

 ber, and a few days later at — 14°.2 R., and all accounts from 

 America speak of an unusual degree of cold. 



But these phenomena are not peculiar to the winter months. 

 The storm which ravaged St. Thomas and Porto Rico on the 2nd 

 of August, was followed in the middle and on the 2 1st of the same 

 month by two very violent storms, which are described in detail 

 in Col. Reid's work ; at the same time unusual heat, accompani- 

 ed by most violent storms of wind and heavy rain, prevailed in 

 Europe. From the 10th to the 20th of August, the thermome- 

 ter stood at 4-30° R. in Messina, and between +28° and +30° 

 at Naples; on the 12th it stood at +30° at Rome, whilst at 

 Rothen and in the Emmethal the torrents, swollen by the violent 

 rains, swept along rocks of 60 cwt. In Silesia the heat was op- 

 pressive. In Gallicia and Prussia this unusual heat was followed 

 near the end of the month by a remarkable cold. This had pre- 

 vailed in America during the great heats in Europe, for at Roches- 

 ter, in the state of New York, on the 4th of August, the extraor- 

 dinary phenomenon of a night frost had been witnessed. 



If in these meteorological phenomena of the temperate zone 

 we recognize the manifest influence of the quickly succeeding 

 disturbances of the atmosphere within the tropics, we shall at 

 once see the reason why deviations from the order of change in 

 the direction of the wind, which results from the law of rotation, 

 namely, S. W. N. E., are a sure sign of very unsettled weather ; a 

 remark which has been made by almost all observers who have 

 carefully examined the connexion of the direction of the wind 

 with the accompanying phenomena of the weather. On the 

 northwestern side of a rotatory storm the wind vane turns N. W., 

 W., S. W. ; the usual order, according to the law of rotation, be- 

 ing exactly opposite, i. e. S. W., W., N. W. 



We thus see that the rotation of the earth on its axis causes 

 three different phenomena: — 1. The constant direction of the 

 trade winds, and the regular alternation of the monsoons. 2. The 

 regular order in the change of direction of the wind, which in 

 both hemispheres is with the sun. 3. The rotatory movement 

 of storms in a determinate order. 



Vol. xliv, No. 2.— Jan.-March, 1343. 43 



