of the United States. 203 



easterly winds should be extremely humid as well as warm ; 

 whilst the normal westerly wind, which has crossed the rocky 

 mountains as well as a wide extent of continent, must be ex- 

 tremely dry as well as cold. Now the warm and moist air 

 being once conveyed to the previously cold and dry localities 

 where the storm appears to originate, the subsequent order 

 and succession of the phenomena are sufficiently intelligible. 

 The fact of which it seems most difficult to render an expla- 

 nation, and to which therefore attention may be profitably 

 directed, is that of the apparent tendency of the south and 

 south-easterly winds to insinuate themselves in the lower 

 stratum of the air, and to prevail over the regular and normal 

 west wind, whenever the latter has moderated after its tem- 

 porary violence. The phenomenon is confined to the lower 

 stratum of the air, as the direction of the upper clouds is pre- 

 served steadily from the west. Mr. Loomis suggests in ex- 

 planation that the momentum which the westerly wind ac- 

 quires at its period of violence causes it to overblow itself, 

 and produces a reaction, each storm having thus, as he con- 

 ceives, a direct tendency to produce its successor. Is it not 

 possible that the elastic force of the vapour rising over the 

 heated surface of the ocean to the south and south-east of the 

 United States, and making its way to the dry interior of the 

 continent, may have a tendency to impede and counteract the 

 current of air proceeding from an opposite direction ? It is not 

 inconsistent with the notion of the independence of air and 

 vapour when at rest, that when in motion either should affect 

 the other. It is I believe a common opinion that air in motion 

 carries vapour with it ; the supposition here made is the 

 counterpart of this. I remember to have heard that at New- 

 foundland, — where the north-west (the prevailing) wind is par- 

 ticularly cold and dry, and where the surface of the sea to the 

 south-east is of unusually high temperature for the latitude, 

 owing to the gulf-stream, the sea fog, as it is called, — fre- 

 quently makes its way from seaward against the wind ; and 

 that the wind then gradually dies away and is succeeded by 

 a gentle breeze from the opposite or sea quarter. 



But whatever may be the fate of conjectures which may be 

 hazarded before the true explanation of the phenomena shall 

 be arrived at and generally accepted, the very clear and lucid 

 manner in which Mr. Loomis has arranged and combined the 

 facts which he has collected together, and the ability and true 

 philosophical spirit in which he has discussed them, call for 

 our grateful acknowledgements, and cannot fail to operate as 

 a stimulus to the co-operators in theUnited States to persevere 

 in their meteorological observations. Mr. Loomis has ex- 



