348 GRISCOM ON METEOROLOGICAL OBSERVATIONS. 



and cannot but consider them as adding value to the series of journal- 

 ized events. 



However fleeting and changeable the forms and arrangement of the 

 clouds may appear to an ordinary observer, it is, we know, upon such 

 forms and arrangements that the judgment is most correctly founded, 

 with respect to the probability of an alteration of weather. But the 

 skill of the weather-wise, for want of a more precise, technical language, 

 remains almost altogether empirical. An attempt to remedy this 

 defect, was made some years ago by Luke Howard, by the invention of 

 a nomenclature applicable to the various forms of suspended water; or, 

 in other words, to the modifications of clouds. " By modification is to 

 be understood, simply, the structure or manner of aggregation, not the 

 precise form or magnitude; which, indeed, varies every moment in 

 most clouds. The principal modifications," he observes, " are com- 

 monly as distinguishable from each other as a tree from a hill, or a hill 

 from a lake ; although clouds of the same modification, considered with 

 respect to each other, have often only the common resemblances which 

 exist among trees, hills, or lakes taken generally." 



" There are," he finds, " but three simple and distinct modifications, 

 which he thus names and defines : 



" 1st. Cirrus. A cloud resembling a lock of hair, or a feather. 

 Parallel, flexuous, or diverging fibres, unlimited in the direction of their 

 increase. 



*' 2d. The Cumulus. A cloud which increases from above, in dense, 

 convex, or conical heaps. 



" 3d. The Stratus. An extended, continuous, level sheet of cloud, 

 increasing from beneath. 



" There are two modifications which appear to be of an intermediate 

 Tiature; these are 



