188 



at a certain distance from the place of greatest storm the swell 

 will proceed, modified only by the common wind which it 

 will either outrun, or follow, or cross, according to circum- 

 stances, — nothing being more common at sea than to have the 

 wind in one direction and the swell in another. 

 All storms are I strongly suspect that a squall is a storm in miniature, or 

 scendS cur- *^^'^ ^^' ^*°^"^^ ^^^ produced by descending streams from the 

 rents of\yii)d, upper part of the atmosphere, caused, in some instances, by 

 squaiis"^'^^ ^^^^ ^^^^ of great masses of water, and in others by chemical pro- 

 cesses, concerning which we scarcely dare to form a conjecture. 

 Uncommon The white squall, or squall without rain, in the Chinese seas ; 

 s?o" ms. ° Whi'te ^^^ ^JP'^o"' o^ Storm of twelve or eighteen hours, which, in the 

 squall; ty- same regions, comes on suddenly, and blows with extreme vio-. 

 of'st" neV° nar! ^'^"^^' '" succession from almost every point of the compass; 

 row streams of the sudden condensation or production of ignited stones, which 

 ' ^' have so often fallen with great agitation of the atmosphere; 



the limited streams of air which have been known to rush across 

 the face of a country, making a narrow line of devastation ; — • 

 these, and many other facts of whirlwinds, waterspouts, ex- 

 plosive noises, and the like, shew that the air may be put into 

 violent motion by other causes as well as its change of elastici- 

 ty from heat and cold, and the mechanical action of descends 

 ing water. 

 Concluding re- Whatever great and powerful agent may therefore cause tlie 



marks. descending air to throw the sea into a swell, it does not neces- 

 I he swell, i /• n i 



caused by a sarily follov/ that the swell shall exist only in the vicinity of the 



storm, may be blast which occasioned it. The centre of action, if it may bo 



propagated . -^ 



with a greater SO called, may either be stationary, or it may move along with 



mean velocity ^ny determinate degree of velocity. From the nature of th^- 



than the storm . . 



that causes it, Case, its motion wJU be such as to follow or coincide with that 



and ma^f there- ^f j-jj^ s„,gij ^f causes. Whenever a heayv swell arrives upon 

 tore arrive on a . . ■' ' 



poast befoie it, any coast, it will, according to the doctrine here laid down, 



indicate that a storm or long continued squall has existed, and 

 probably continues to exist, towards that point of the compass 

 from which the swell arrives. If its progressive velocity and 

 duration be sufficient, the storm will arrive at the coast subse- 

 quent to the swell, unless its first generation or commencement 

 —orcomc after was near the shore ; but we may suppose, and undoubtedly it 

 SaseT'" *'*^ °^^^'" ^^ happens, that the atmospheric cause of the swell may 

 have ceased long before the swell itself has subsided. 



ir. 



