[ 485 ] 



2do. The dirc£lion of the wind feems merely a contingent 

 circumftance, yet as this phoenomenon, or at leaft its caufe, ori- 

 ginated in the fouthern part of Europe, it poflibly has been ex- 

 tended northwards by a fouthern wind. 



3^. While the impetus of the eruption of this air lafted, it 

 may well be fuppofed to reach the greateft heights like the ftill 

 denfer fmoke of volcanos ; but, as it confifted chiefly of heavy 

 inflammable air, it may be inferred that it gradually defcended and 

 its heterogeneous contents became vifible every where nearly at the 

 fame time, but its height for a long time fecured it from the 

 winds that prevail in the lower ftrata of the atmofphere ; but 

 when it had defcended forae way thefe winds and rain gradu- 

 ally difperfed and waflied it away. 



4®. The atmofphere, thus loaded with metallic and other par- 

 ticles thrown into it far beyond the limits fuited to their fpeci- 

 fic gravity, muft have its weight increafed, and hence the extraor- 

 dinary heights of mercury in barometers. While diff'ufed over 

 vaft fpaccs, the additional weight accruing to the atmofphere from 

 thefe particles may have been infenfible or not eafily diftinguiflied, 

 but became evident when they had fomewhat defcended and were 

 concentrated, and hence the varying accounts we have had of 

 the manner in which barometers were affeded during the mift ; 



Vol. VIII. 3 P neither 



