( ^S3 ) 



heen taken tip by them zvhen in a fiuid 

 Jiatc^ iior formed within them at the time 

 of their congelation — Confrmatlon of thefe 

 proofs — 'The Eollan If es placed hi a dlredl 

 line from eafi to ijoefi — A fimllar direction 

 ohfervable In fome ifands and volcanic 

 monntalns in other countries — Not Impro- 

 bable that all the eight Eollan Ifes were 

 formed at the fame tlme^ and perhaps 

 very fiiddenly^ ivlth refped^ at leaf^ to 

 their frf rudiments — -Explanation of the 

 caufe ijuhy ifands and burnwg mountains 

 are fmetlmes produced dlfpofed in a right 

 line — Materials of the Eollan Ifles^for the 

 mof part^ porphyrltlc — Analyfis made by 

 the author^ proving that the red Egyptian 

 porphyries have not for their bafe the pe- 

 troflcXy but rather the hornfone — En- 

 quiry whether the vltrif cations found In 

 fuch prodigious quantities at Vulcano and 

 Llpai'l^ are found in fimllar quantities in 

 any other volcanic countries — Uncertainty 

 of this from the "want of accurate miner a- 

 logical defcrlptlons of the greater part of 

 vokanos — The accounts given of thein 



nfually 



