J814 ©tt A METEOROLOGICAL HOMENCLATURE. 



notessenth! to be will there find the natural history detached from this so 



the natural , , . . ... 



history. much combated hypothesis, and resting solely on its proper 



basis, that of long continued and attentive observation of 

 the phenomena, I undertook to describe and classify. 

 Dr^BosuJck*' In oh .i ec1 ™&» aa * PWI next be obliged to do, to the whole 

 only objection- method of Dr. Bostock in forming his terms, I would not 

 ab * e * be understood to detract from the value of his original ob- 



servations. A continuation of them in more clear and defi- 

 nite phraseology cannot fail to prove useful to the science. 

 To use new terms is in etfect to propose them ior use, or to 

 introduce a new nomenclature. Those of Dr. Bostocl; 

 are liable to objections more apparent than that of being 

 *' uncouth ;" they are inaccurate and imperfect. To make 

 this appear we must examine them singly, which will also 

 give opportunity for the discussion of several facts, to which 

 they relate: and first, the arc, past, present, and future, 

 fbearc. This particular formation of the clouds must have at- 



tracted the notice of most observers of the sky. The struc- 

 ture is not very clear from the Doctor's account. He says, 

 the lines converge to a point in the horizon, and such is cer- 

 tainly tie appearance 10 the eye. In the article Cloud be- 

 fore mentioned, the reader will find it thus noticed : " It 

 fHVfc cirrus) is sometimes spread horizontally through a vast 

 extent of atmosphere; the whole breadth of the sky being 

 insufficient to show where it terminates. In this case, its 

 parallel bars appear, by an optical deception, to converge 

 in opposite points of the horizon." These parallel bars are 

 the linear arc of Dr. B. W hen the cirrus is compound, we 

 have h\* feathered u.c ; and in varieties of the cirrocumulus, 

 the mottled and wreathed arc. Now, although each of these 

 linear clouds may, in some sense, be an arc, as following 

 the curve of the Earth's surface, yet it is not this curve which 

 the eye perceives, but a system of converging lines. The 

 term arc therefore, applied to such a system, seemed so un> 

 philosophical, that 1 could not imagine whence it came; t\\\ 

 I remembered that the name of Noah's ark is given, ia po-r 

 pular language, to an assemblage of clouds, the nature of 

 ' which is not very obvious from the name. Recollecting 

 this I was led to suppose, that Dr. B. had borrowed the 

 gpuud, though not the sense* .of this popular allusion to the 



orderly 



