l 
200 Jounston-Lavis—The Eruption of Vesuvius in April, 1906. 
Vesuvius has every reason to maintain its reputation as the most interesting 
type-voleano of the world, which title I have on several occasions ventured to 
claim for it. In this study I have endeavoured to limit myself to purely 
vulcanological issues, and to study only those phenomena that would help us to 
elucidate the highly complex problems of volcanic action. Minor details of 
petrography and mineralogy have been purposely eliminated to make the main 
physical and chemical aspects of the question stand out more clearly. 
I take this opportunity of returning thanks to Mr. F. A. Perret for permission to 
reproduce his photograph of the slip on the Vesuvian cone; to Professor Semmola 
for the meteorological data; to Professor V. Sabatini for the use of the transfer 
for the map of the lava streams ; to the Director of the Istituto Geografico Militare 
for permission to use, and for the reproduction of, the map of the crater. I wish 
to express my thanks to my old friends Signor L. Jacono, of Torre Annunziata, 
and Mr. H. Elliott, of Naples and Milan, for much information and help. My 
obligations are also due to Profs. Bassani and Loczy, and to Messrs. Galdieri, 
Matteucci, Mercalli, Guppy, and Ferber, for their kind assistance. My gratitude 
is more especially due to Prof. Grenville Cole for help in many ways, as well as 
for several valuable criticisms and suggestions. 
