28 A COMPARISON BETWEEN THE CLIMATES OP 



Sometimes when the weather is very foggy in the morning, the 

 hygrometer exposed to it will not be dewed or moistened until the 

 temperature of the dark bulb be reduced two, three, or four degrees. 

 When this occurs, the fog is usually succeeded by a clear and fine 

 day. 



The following Table of the wind is arranged in accordance with 

 the remarks made in the second volume of The Analyst, p. 221 ; 

 and it appears that those to the south of the east and west points of 

 the compass, in comparison with those to the north of these points, 

 were, in the former year, as 15 to 10 at Malvern, and in the latter 

 as 18 to 10 ; and they bore very nearly the same relation to each 

 other in London — the numbers being, for the first year, 15 and a 

 fraction to 10, in the last 19 to 10. 



TABLE IV Of the Wind at Malvern and London for the Seasons of 



1834-5 and 1835-6. 



Two or more different currents of wind may be frequently de- 

 tected by observing the clouds. Sometimes the higher ones may 

 be seen nearly stationary, the lower moving rapidly, either at vari- 

 ous angles to the slow-moving higher ones, or now and then in an 

 opposite direction. The primary indication of a change in the 

 direction of the wind may be detected sometimes by noticing the 

 appearance of clouds, even before they are influenced in their move- 

 ments by the aerial current. They display a great variety of circu- 

 lar segments or curls, in a plane apparently parallel to the horizon 

 i — the convex face of the curl when below the zenith being turned 

 downwards towards the horizon, whereas the convex arch of the 

 cumulus is turned upward towards the zenith. The appearance 

 here spoken of may be difficult to describe, but it is very character- 

 istic. The convexity of the curl is generally in the direction of the 

 approaching current. 



When the air is calm, evaporation is proportionate to the inter- 

 val between the dew point and the temperature of the air ; it is ac- 



