[ 97 ] 



XVIII. On the Modifications of Clouds, and on the Prin^ 

 ciples of their Production, Suspension, and Destruction ; 

 being the Substance of an Essay read before the Askesian 

 Society in the Session 1^02-3. By Luke Howard, 



Esq.* 



OINCE the increased attention which has been given to 

 meteorology, the study of the various appearances of water 

 Suspended in the atmosphere is become an interesting and 

 even necessary branch of that pursuit. 



If clouds were the mere result of the condensation of va- 

 pour in the masses of atmosphere which they occupy, if 

 their variations were produced by the movements of the at- 

 mosphere alone, then indeed might the study of them be 

 deemed an useless pursuit of shadows, an attempt to de- 

 scribe forms which, being the sport of winds, must be ever 

 varying, and therefore not to be defined. 



But however the erroneous admission of this opinion may 

 have operated to prevent attention to them, the case is not 

 so with clouds. They are subject to certain distinct modifi- 

 cations, produced by the general causes which eftc-ct all the 

 variations of the atmosphere : they are commonly as good 

 visible indications of the operation of these causes as is the 

 countenance of the state of a person's mind or body. 



It is the frequent observation of the countenance of the 

 eky, and of its connection with the present and ensuing phe- 

 nomena, that constitutes the antient and popular meteoro'* 

 logy. The want of this branch of knowletlge renders the 

 predictions of the philosopher (who in attending only to 

 his instruments may be said only to examine the pulse of 

 the atmosphere) less generally successful than those of the 

 weather-wise mariner or liusbandnian. 



With the latter, the dependence of their labours on the 

 state of the atmosphere, and the direction of its currents, 

 creates a necessity of frequent observation, which in its turn 

 produces experience. 



But as this experience is usually consigned only to the 

 memory of the possessor, in a confused mass of simple apho- 

 risms, the skill resulting from it is in a manner incommu- 

 nicable ; for, however valuable these links when in connec- 

 tion with the rest of the chain, they often serve, when taken 

 eingly, only to mislead j and the power of eonuecting them, 



* Communicated by the Author. 



Vol. XVI. No. 62. G \a 



July 1803. 



