VOLCANOES. 



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crater, after the lava ceases to flow, and sometimes at noon day in- 

 volve the surrounding country in total darkness. Towards the con- 

 clusion, the colour of the volcanic sand changes to white : it consists 

 of pumice in a finely comminuted state. During an eruption of 

 ^tna, a space of one hundred and fifty miles in circuit was covered 

 with a stratum of volcanic sand or ashes twelve feet thick. When 

 the lava flows freely, the earthquakes and explosions become less vio- 

 lent ; which proves that they were occasioned by the confinement 

 of the erupted matter, both gaseous and solid. The smoke and va- 

 pour of volcanoes are highly electrical. 



The quantity of lava thrown out during a single eruption of a vol- 

 cano, seems almost incredible to those who have not observed volca- 

 nic countries. Kircher, in his Mundus Subierraneus, lib. vi. cap. 

 8., published in 1660, says, that the ejections of Mount jEtna would 

 if collected, form a mass twenty times as large as the mountain it- 

 self; and a few years afterwards, viz. in 1669, the same mountain 

 covered with a fresh current of lava eighty four square miles; and 

 again in 1775, according to Dolomieu, the same volcano poured out 

 another stream of lava, twelve miles in length, one mile and a half in 

 breadth, and two hundred feet in height. Hence it is evident that 

 the seat of the fire is not in the mountain itself, but deep in the earth : 

 the volcano is not the furnace, but the chimney ; and it will be necessa- 

 ry to bear this in mind, if we would form an adequate idea, of the exten- 

 sive effects of volcanic action. Seneca appears to have formed a dis- 

 tinct notion of the seat of volcanic fire, when he remarks, that the vol- 

 cano does not supply the fire, it only affords it a passage " in ipso 

 monte non alimentum hahet sed viam.^^ The largest known current of 

 modern lava was formed by a volcano in Iceland in 1783 ; it is sixty 

 miles in length, and twelve broad, equalling in extent any continuous 

 rock formation in England. The most extraordinary volcanic erup- 

 tion recorded in history for the extent of its effects, took place in 

 Sumbawa, one of the Molucca Islands, in April, 1815. It is des- 

 cribed in the history of Java, by Lieutenant Governor Raffles. 



" This eruption extended perceptible evidences of its existence 

 over the whole of the Molucca Islands, over Java, a considerable 

 portion of Celebes, Sumatra, and Borneo, to a circumference of a 

 thousand statute miles from its centre, by tremulous motions and the 

 report of explosions ; while within the range of its more immediate 

 activity, embracing a space of three hundred miles around, it produ- 

 ced the most astonishing effects, and excited the most alarming ap- 

 prehensions. In Java, at the distance of three hundred miles, it 

 seemed to be awfully present. The sky was overcast at noon day 

 with clouds of ashes ; the sun was enveloped in an atmosphere, 

 whose ' palpable' density he was unable to penetrate ; showers of 

 ashes covered the houses, the streets and the fields, to the depth of 

 several inches ; and amid this darkness, explosions were heard at 

 intervals, like the report of artillery or the noise of distant thunder. 



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