426 



F A. Ferret— Yes 



UVIUS. 



showing beautiful erosion effects with arborescent trickle-pat- 

 terns of great delicacy.* 



5. The last eruption left great masses of material in unstable 

 equilibrium around the inside of the crater's edge, and from 

 time to time these were precipitated into the abyss, compress- 

 ing the air by their fall, and were then ejected as immense 

 dust-clouds which so perfectly resembled true explosions that 

 reports of a new eruption were frequently seen in the news- 

 papers. One of these great downfalls occurred while I was 

 visiting the United States, and I took occasion to deny the 



Fig. 10. 



Fig. 10. Vesuvius — Effect of a large internal avalanche. 



report of an eruption and published an explanation of the 

 phenomenon in the New York papers. 



The downfall of these large masses soon raised the floor of 

 the crater to a point some three hundred meters below the rim 

 and subsequent avalanches have formed a series of talus cones 

 around the circumference of this floor which are constantly 

 growing and thus reducing the size of the flat, central area. 



I use the word "avalanche" instead of "dry slip" or "land- 

 slide" as it conveys a more adequate idea of the grandeur of the 

 phenomenon. Slips and slides are continually occurring, but 

 the descent of a true avalanche in the present crater of Yesuvius 



* Compare Jaggar's "Experiments illustrating Erosion and Sedimenta- 

 tion." Bulletin of the Museum of Comparative Zoology at Harvard College, 

 vol. xlix, 285, 1908. 



