4 J. W. Judd — On Vokanos. 



in dealing with one of the natural sciences ; but when we find that 

 not a few of the data and principles of calculation on which he relies 

 are disputed by authorities of equal eminence with himself in their 

 special departments, geologists may be forgiven for thinking that 

 the tone assumed by him in dealing with this subject was scarcely 

 warranted. Nor is their confidence in the value of his speculations 

 increased, when they find him arriving by means of them at con- 

 clusions totally at variance with the clearest results of geological 

 observation, — such, for example, as that ordinary explosive volcanic 

 eruptions did not take place during the Palaeozoic period ! 



We are far from denying the advantage of inquiries and specula- 

 tions of this character. It cannot but be of interest to the student 

 of Geology, and at the same time calculated to afford him suggestions 

 in the carrying out of his investigations, to see how far the con- 

 clusions at which he has arrived by direct observation can be made 

 to harmonize with the hypotheses based on the latest results of 

 Physical Science. But, as these latter are continually undergoing 

 modification and development from the progress of research, we 

 must ever be on the guard against allowing such theories to have 

 undue weight, or being supposed capable of replacing the methods 

 of geological inquiry, at first so well developed by Hutton, and 

 afterwards so clearly illustrated by the labours of Lyell, Scrope, and 

 Darwin — methods based on the principle that the explanation of the 

 phenomena of the past can only be obtained by a study of the 

 operations which are still going on around us. 



In giving a series of sketches of the structure and phenomena of 

 some of the most interesting volcanic districts in Europe, we shall 

 endeavour, as far as possible, to avoid all subjects of a purely specu- 

 lative character, and it will be our chief aim to direct especial 

 attention to those features which suggest analogies with the volcanic 

 formations of former geological periods, and appear to be calculated 

 to throw light on the nature and succession of those operations by 

 which these latter have been originated. While dwelling, however, 

 upon the more general features of geological structure and igneous 

 action, in our descriptions of the several districts, we shall endea- 

 vour not to lose sight of any of those results of chemical, minera- 

 logical, or microscopical research which appear to throw light upon 

 the subjects of our studies. Our object, in short, will be to confine 

 these studies within what we have indicated as being the most im- 

 portant and legitimate paths of geological inquiry, — namely, the 

 investigation of the structures and operations of extinct and active 

 volcanos, with a view to arriving at the laws which have governed 

 the developments and manifestations of igneous forces, alike in past 

 geological periods and during the existing epoch. 



I. — The Lipaki Islands. 



There is certainly no district in Europe, and perhaps none in the 

 whole world, which affords such beautiful illustrations of the phe- 

 nomena of volcanic action, and at the same time offers such re- 

 markable facilities for their investigation, as the little group of 



