197 



as altogether conjectural, but probably as remote as the arctic circle, 

 thus extending over 70° of longitude and 40° of latitude. The 

 question whether the remarkable storm which occurred in Europe, 

 about the 25th of December, was a continuation of this storm, is exa- 

 mined, and the author concludes, from a discussion of its peculiarities, 

 that it was not — the progress of the barometric minimum in Europe 

 being from north to south, inclining a little to the west. 



The author next proceeds to generalize the deductions in regard to 

 the circumstances of this storm, and to apply them as tests to the dif- 

 ferent theories of wind, rain, &c. 



He first endeavours to show how far registered observations of the 

 wind may be influenced by localities, and their accuracy affected by the 

 mode of observing, and the transcribing of the registers ; and con- 

 cludes that it is indispensable to regard the average of directions at 

 near stations, and not those at individual ones, and gives some exam- 

 ples of discrepancies at places near each other, in support of this opi- 

 nion. The anomalies presented by the stations in the state of New 

 York are very curious. 



The causes assigned by theory for the production of winds are next 

 enumerated and discussed. Recurring to the observations, the author 

 traces a connexion between the direction of the surface wind on the 

 18th and 19th of December, and a maximum of the barometer exist- 

 ing on a line nearly north and south, moving eastwardly, and pass- 

 ing, on the morning of the 20th of December, nearly through the east- 

 ern extremity of the State of Maine. At this period a minimum of 

 the barometer existed nearly on the line of the river Mississippi, and 

 the winds blew towards this line. This minimum is traced in its 

 motion eastward ; and in connexion with it, the change of wind from 

 the easterly to the westerly quarter. On the afternoon of the 21st, 

 the line of minimum pressure had reached Boston; and on the 22d, 

 the north-westerly wind now prevailed at nearly all the stations. The 

 direction and approximate force of the wind, on the morning of the 

 21st, are represented upon a map of the United States, accompanying 

 the memoir. From an examination of a phenomenon of the wind, 

 Prof. Loomis concludes that the south-easterly current rose, so that 

 the north-westerly wind thus became the lowermost current; and 

 subsequently, from an examination of the phenomenon of the rain, 

 snow, and hail, that the rising current was, in part at least, deflected 

 back upon itself. The immediate cause of the south-easterly wind is 



