Earthquakes and Volcanoes 



effected in the character of a volcano by succes- 

 sive eruptions, new cones being thrown up at 

 one time, and old ones obliterated at another. 

 Fig 54, shows the summit of Vesuvius as it ap- 

 peared in 1756, when there were no fewer than 

 three separate cones, one within another, en- 

 circling as many craters. But about ten years 

 afterwards the summit presented the form 



FIG. 54. Summit of Vesuvius in 1756 



shown in Fig. 55, where a single cone rises from 

 the floor of the great crater. The curious stages 

 through which a volcano may pass are well illus- 

 trated by the story of Vesuvius. 



Rather less than two thousand years ago, that 

 mountain was as peaceful as Primrose Hill is at 

 the present day. It seems from all accounts 

 to have had a very regular conical shape, with a 

 crater about a mile and a half broad. Yet its 

 shape led hardly any one to suspect that the 

 mountain was a slumbering volcano. Wild 

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