534 G. Poulett Scrope — The Mechanism of Stromboli. 



panied with steam, which pierced these clouds at each outburst. 

 But other observers, especially Spallanzani in 1788, Hoffmann in 

 1831, and myself in 1819, were more fortunate, and saw at the 

 bottom of the crater nothing in any respects resembling a geyser, 

 but an orifice some seven or eight yards wide, full to the brim of 

 seething white-hot lava, which swelled up from time to time in a 

 dome-like form, and then fell again by some few feet below the 

 mouth of the orifice, after giving issue to a burst of vapour mingled 

 with scoriaa. That in its normal condition the throat of the volcano 

 is so filled with fluid lava almost to the brim, is conclusively proved 

 by the strong light reflected from the vapour-cloud above at every 

 outburst of the red-hot scorise, which is seen nightly in the offing, 

 and renders Stromboli a valuable lighthouse to mariners. This is, in 

 fact, the ordinary condition of every volcano when in eruption. Such, 

 for example, were the phenomena presented by the crater of Vesuvius 

 on several occasions, as described by Deville, Eoth, Abich, and other 

 trustworthy observers. 



The utter improbability of a geyser occupying the axial chimney 

 of a volcano in more or less active igneous eruption, never seems to 

 have occurred to Mr. Mallet's mind. Is it then a geyser that from 

 the beginning has thrown up the volcanic agglomerates and lavas 

 of which the island is wholly composed ? Was it the geyser that 

 blew away one large segment of the mountain, and formed the 

 great breached crater ? Or does the existence of the geyser only date 

 from that paroxysmal eruption, when the present phase of moderate 

 or sluggish enaptive activity probably began ? Geysers occur in 

 considerable numbers in Iceland, New Zealand, and other volcanic 

 districts. But who ever saw one in the crater of a volcano, or 

 throwing up red-hot lava ? The geysers of Iceland are found in 

 numbers close together upon a slightly raised platform in a valley 

 — evidently the surface of a deep bed of lava which has flowed from 

 Hecla, or some neighbouring volcano — the internal heat of which lava 

 is still sufficient to produce the phenomena. The Great Geyser is 

 about 70 feet deep. But if we correct Mr. Mallet's measurements of 

 heights to make them agree with the truth, we shall find the depth 

 of his imagined geyser tube from its mouth at the bottom of the 

 crater to the sea, to be not 300 feet, as he represents it, but near 

 2,000. And this prodigious tube we are called on to believe is filled 

 with hot water, and emptied again to the bottom at every explosion 

 (p. 511). But, again, what is to prevent the heavy liquid lava, 

 together with the fragmentary matter that falls or rolls to the bottom 

 of the crater after each outburst, from entering the oj)en mouth 

 of the water-tube the moment it has been emptied of everything 

 but air or vapour at the atmospheric pressure (which is Mr. Mallet's 

 assertion), and filling it up so as to put an end to his geyser ? Mr. 

 Mallet tries to meet this obvious objection, by suggesting a jam of 

 the coarser fragments cemented by lava and acting as a stopper. But 

 is it conceivable that such an accidental jam should have occurred 

 not once or twice only, but about ten times in every hour for the last 

 2,000 years or so ? It is scarcely worth while, after these conclusive 



