THE COASTS OP SICILY. 109 



appeared at that fatal epoch. We had also traversed 

 the cheire, which had advanced into the sea beyond 

 the harbour in the form of a promontory, whose 

 surface resembles that of a river on which the ice is 

 breaking up, and whose immoveable and dark blocks 

 frequently present surfaces of several hundred square 

 feet, and are from fifteen to twenty feet in thick- 

 ness. In visiting spots like these, the very aspect 



saw the stones rebound, and occasionally break in pieces on the 

 surface of this apparently liquid stream. These facts, however, are 

 well known to all those who have been eye witnesses of these 

 terrible phenomena. 



This special characteristic of the lava explains to us how several 

 venturesome travellers, and amongst others, Hamilton and the 

 Marquis Galliani, were able to cross moving lava beds, without 

 experiencing any inconvenience beyond the sensation of intense 

 heat in the feet and legs. It ought further to be observed that 

 stony substances are bad conductors of heat, which will explain on 

 the one hand how it is that the lava proceeds with so much slowness ; 

 and on the other, why it requires so long a time before it becomes 

 completely solidified and cooled. We have already shown that the 

 burning stream which issued from the Monti Rossi continued its 

 progress for forty-six days before it reached the borders of the sea, 

 at a distance of about twelve miles, and nevertheless in this case the 

 enormous mass of igneous matters that was constantly being ejected 

 from the volcano accelerated its course. In the eruption which 

 continued for ten years, viz. from 1614 to 1624, the current of lava 

 although it was constantly augmented, traversed only a distance of 

 ten miles. On the other hand, the lava of 1819 advanced at the 

 rate of a yard a day nine months after the eruption had ceased. 

 Spallanzani in 1787 saw a walking-stick smoke and catch fire a few 

 minutes after it had been introduced into a fissure, which was still 

 glowing from the presence of a stream of lava, that had been 

 solidified eleven months before. The cheire of the eruption which 

 we have described, continued to smoke, and to give off a very 

 sensible amount of heat eight years after the lava had issued from 

 the Monti Rossi. 



