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The Cirrus cloud is seen at all seasons of the year, 

 and at all heights of the barometer. It occupies the 

 most elevated regions of the atmosphere, and is sup- 

 posed to be above the limit of perpetual congelation (in 

 our latitude about 6000 feet). It is easily distinguished 

 from all other clouds by its delicate, fibrous, thread-like, 

 curling or feathery texture ; it lies in light patches on 

 the blue sky, sometimes so faintly that the eye can 

 scarcely discern it ; its motion is very slow, and in se- 

 rene weather with a high pressure it will retain its form 

 unaltered for many hours. If the mercury be falling, 

 its changes are rapid ; and on the approach of rain its 

 delicate texture becomes confused, and is ultimately lost 

 in one dusky mass, resembling ground glass. During 

 these changes the Cirrus has been descending; and its 

 peculiar characteristics having disappeared, it assumes 

 a new nomenclature, the Cirro- Stratus. The progress- 

 ive increase of the Cirrus cloud is generally from the 

 west. 



The Cirro- Stratus is likewise in the higher regions of 

 the atmosphere, and is seen at all seasons of the year : 

 it is the immediate precursor of rain or wind and of a 

 falling barometer. Sometimes it spreads itself over the 

 heavens so attenuated, that the sun, though it shines 

 through it, casts its shadows indistinctly; at other 

 times it spreads itself in lurid darkness, threatening 

 storm and tempest, but terminating in rain or wind. 

 If, after a rapid rise in the mercury, this cloud make its 

 appearance in bars, or streaks which seem to converge 

 in the horizon, rain shortly follows. It is in the Cirro- 



