THE COASTS OF SICILY. 121 



from the cone and distribute over this nearly hori- 

 zontal surface. Here a curious comparison presents 

 itself to our notice. The mud of the Nile every year 

 raises the soil which it fertilises about one- twentieth 

 of an inch ; and thus, as M. de Beaumont remarks, 

 the monuments of Thebes and of Memphis are being 

 more rapidly buried under the alluvial deposits of 

 this river, than the Torre del Filosopho is being en- 

 tombed by the ashes of Etna. 



Nevertheless, there is a fact which at first sight 

 appears to be opposed to the preceding views. The 

 terminal cone of Etna is formed with tolerable rapi- 

 dity, for from time to time, as we have already seen, 

 it sinks into the abysses of the volcano, and a few 

 eruptions suffice to restore it to nearly its former di- 

 mensions. In 1702, the Piano del Lago presented 

 the appearance of a plateau, in the centre of which 

 there opened a gigantic funnel. This was the crater, 

 which had been greatly enlarged, and whose orifice 

 opened on a level with the ground, like that of a 

 well which is unprotected by any parapet. The 

 present cone is not more than a century old, yet in 

 1834 it was ]394 feet in height, while its circum- 

 ference at the base measured 16,410 feet. Have 

 the matters which have been ejected from the vol- 

 cano been the only agents which have contributed to 

 its elevation ? If such were the case, it would be 

 extremely difficult to explain why the Piano del 

 Lago has not been completely overwhelmed by the 

 cone during the course of nearly twenty centuries ; 

 and it would be more especially difficult to under- 

 stand why such abundance of ejected matters should 



