Atmospherical Phenomena. ^QS 



Influence of the Direction of the Wind on the Barometer. — 

 The connection of the pressure of the air with the tempera- 

 ture is proved by few facts in so remarkable a manner, as by 

 the influence exercised on the barometer by the direction of the 

 wind, a fact which has been more particularly placed in a clear 

 light by L. Von Buch. If we observe the barometer at a place 

 for some length of time, and ascertain its height during each 

 separate wind, we find that it is lowest during south-west winds ; 

 that as we proceed farther from this point, through the west or 

 east points of the compass, it gradually rises ; and that during 

 north-east winds it stands, on an average, several lines higher 

 than during south-west. This contrast of south-west and north- 

 east winds is pretty general throughout the whole of Europe, 

 while on the east coast of North America the extremes lie more 

 in the NW. and SE. The cause of this fact is extremely sim- 

 ple, for since SW. and NE. are the points from which the 

 warmest and coldest winds blow, the barometer gives only the 

 difference of temperature of the two winds. 



Dove has added a fact to this investigation, which stands in 

 intimate connection with his view regarding the shifting of the 

 wind, and enables us to understand more ^easily the irregular 

 changes of the weather which are therewith combined. If 

 we observe the barometer frequently in the morning and 

 evening, and take the wind which blows between these periods 

 at about noon ; and if now we apply to each wind a morning 

 and evening observation separately, we find that the barometer 

 during SW. and NE. winds alters but little in the course of 

 the day, whereas during a west wind it rises, and during an 

 east sinks. Dove has proved this by observations continued 

 for many years in Paris. Tables of observations on the pres- 

 sure of the air made almost hourly at Halle, between B'^a.m. 

 and 10 P.M., for a period of three years, confirm the view in a 

 remarkable manner. As the barometer has almost the same 

 mean elevation at 10 a.m. and 10 p.m., it may be sufficient to 

 indicate the changes in the intermediate period, in which I 

 shall mark the rise of the barometer by +, and the sinking 

 by — . In this manner we find 



VOL. XXVI. NO. LII.— APttlL 1839. S 



