— 63 — 



coutiuued slowly, until at cij^'lit o'clock wlieu tlie is- 

 land WLis completely submerged. " 



There being no essential dift'erence between tlie 

 phenomena of volcanic agency on land and in the 

 ocean, we may infer that this conical island was the 

 result of an eruption from one of the vents of a very 

 lengthening tunnel of lava, lying under the bed of the 

 ocean. The How of lava beneath water, though at 

 first sight an unlikely occurrence, has been repeatedly 

 noticed. Although a certain amount of vaporisation 

 takes place at the first contact of the molten matter 

 with the w:ater, a crust rapidly forms round it, which 

 prevents the further contact of Avater with the molten 

 interior of the stream ; the crust formed, having a very 

 low conducting power checks tlie escape of heat. In 

 this way a constantly lengtlieniug tunnel is formed, 

 within which the molten matter pursues its course for 

 very long distances, in some cases the lava streams 

 extend to some hundreds of square miles. A repeti- 

 tion of eruption may be caused in streams of lava by a 

 sudden accession of heat below, wherefore the melted 

 rock then forces out a way for itself which thus gives 

 rise to new vents. Such was evidentl}'" the case in the 

 formation of the Conical Island reported above. In 

 many cases volcanic matter has been observed to be 

 emitted from a number of vents ranged in a straight 

 line accross the country. 



A'Vherefore it is reasonable to ouppose that tlie 

 same phenomena may occur in tlit; seabottom. The 



