J. W. Judd — On Volcanos. 211 



to S.E., through the Sciarra del Fuoco, the summit of the moun- 

 tain, and the Punta dell' Omo. This section is based on the large 

 map constructed by the Italian Instituto Topografico Militare, and on 

 the splendid Chart of the Lipari Islands issued by the French 

 Government, from the surveys made by MM. Darondeau, Gaussin, 

 Boutroux, Manen, Larousse, and Vidalin in 1857 and 1858. In all 

 its main details, too, the accuracy of this section is confirmed by 

 the English and Neapolitan Admiralty Charts, and by the observa- 

 tions of Abich, Hoffmann, and other geologists. 



Both of the official documents referred to give the height of the 

 mountain as over 3000 feet. The elevation of the ridge overlooking 

 the crater, which Mr. Mallet states as only 1200 feet, has been 

 shown by repeated measurements, which I can myself confirm, as 

 being only about 600 below the summit,, or at least 2400 feet, 

 that is, twice the amount given by Mr. Mallet ! 



The outer lip of the crater (or, in other words, the top of the 

 inclined plane of the Sciarra del Fuoco) and the bottom of the crater 

 are points quite inaccessible to the observer ; but there nevertheless 

 exist means of estimating their true elevation above the sea-level. 

 Abich, who under-estimated the height of the summit of the moun- 

 tain by about 200 feet, on the supposition that the inclination of the 

 Sciarra was only 30°, fixed this point at 1645 feet above the sea- 

 level. Mr. Mallet measured the slope of the Sciarra with the clino- 

 meter as from 34° to 36° with the horizontal, and I am convinced 

 from my own observations that 35° is about a fair average. The 

 exact position of the crater and its relation to the other parts of the 

 island being given in the map of the Italian Government, we are 

 thereby able to fix the elevation of this point as a little over 2200 

 feet. Mr. Mallet states it to be only 600 feet ! Calculating from the 

 positions of the several points as given on the map, this would make 

 the slope of the Sciarra only 11°, which is not only quite at variance 

 with Mr. Mallet's own measurements, but would be at once rejected 

 by every one who had seen either the island itself or any drawing of 

 it. With respect to the elevation of the bottom of the crater, which 

 is probably liable to constant variation within small limits, I am in 

 the same predicament as Mr. Mallet, having never succeeded in 

 getting a sight of the crater-floor, owing to the clouds of vapour pro- 

 ceeding from the fumaroles. Several accurate observers who have 

 seen it, however, declare it to be situated only a short distance below 

 the outer lip. The estimate of at least 2000 feet, which most 

 authors have given for the elevation of the bottom of the crater of 

 Stromboli, we must, therefore, regard as certainly below the truth, 

 while Mr. Mallet's statement that it "cannot be more than 300, 

 or at most 400 feet, above the level of the sea," is altogether 

 erroneous. 



Lastly, Mr. Mallet's assertion that the Admiralty Chart indicates 

 " that for some miles in the offing here the Mediterranean does not 

 exceed 100 fathoms in depth," is to me simply inexplicable — since the 

 English, French and Neapolitan Admiralty Charts all give numerous 

 soundings of more than twice that amount, within a mile of the 



