376 WASHINGTON AND DAY VOLCANOES OF SOUTHERN ITALY 



the general chemical characters of the igneous magmas,^ it is of some 

 petrological, and possibly of vulcanological, interest to ascertain whether 

 the lava gases show analogous correlations with the composition of the 

 magma in which they are found. 



We visited the volcanoes of Vesuvius, Etna, and the ^^olian Islands in 

 the summer of 1014. The general results of our observations and studies 

 of the material collected, including gases, salts, and rocks, will be pub- 

 lished later. The object of the present paper is only to \m\ on record the 

 state of activity and other conditions obtaining at the several volcanops 

 during June, >Tuly, and August. 11)14. Although the volcanoes were quiet 

 during the summer, the record may be of some value, as it is coming to 

 be generally recognized that study of the repose periods of volcanoes is or 

 may be of great importance in the interpretation of their phenomena 

 during activity, as well as useful in the prediction of eruptive periods. 



We take this opportunity to express our great appreciation of the 

 valuable assistance and many courtesies rendered us by all the Italian 

 officials and scientists with whom we came in contact, among whom may 

 be specially mentioned : His Excellency the Minister of Public Instruc- 

 tion ; Professor A. Malladra, Director of the Vesuvius Observatory ; Pro- 

 fessor A. Ricco, Director of the Observatory at Catania : Professors L, 

 Bucca, Gaetano Platania, and G. Ponte, of Catania, and Professor J, 

 Friedlander, of Naples, 



Vesuvius 



Since the eruption of 1906 there has been a continuous condition of 

 "repose," the features of which have been described by several geologists.^ 

 This period of repose has been the longest recorded since the beginning 

 of the eighteenth century. According to Mercalli's'^ data, the average 

 duration of the eleven well-marked repose periods which have followed 

 the more prominent eruptive climaxes since 1712 has been about 3.3 

 3^ears, while after the great eruption of 1906 some seven years elapsed 

 before the volcano gave any decided evidence of entering on a new period 

 of activity. 



s H. S. Washington : Trans. Am. Inst. Min. Eng., 1908, p. 735. 

 * F. A. Ferret : Am. .Tour. Sci., vol. xxvili, 1909, p. 41."^. 

 G. MercaUi : Rend. Ac. Sci. Nap., vol. xix, 1913, pp. 134. 137. 

 A. Malladra : Rend. Ac. Sci. Nap., vol. xviii, 1912, p. 224. 



A. Malladra : Rend. Ac. Sci. Nap., vol. xix, 1013. p. 153 : Boll. R. Soc. Cieog.. 1914. 

 p. 753 ; Rend. Ac. Sci. Nap., vol. xx, 1914 ; Boll. R. Soc. Geog. Ital., 1914, p. 1237, with 

 map of crater ; Zeits. Vulk., vol. i, 1914, p. 104. 



I. Friedlander : Natiirw. Wochens., vol. x, 1911, p. 454. 



I. Friedlander : Naturw. Wochens., vol. xii, 1913, p. 389 ; Peterm. Mitth., 1912 ; maps 

 of the cone and crater of Vesuvius, Naples, 1913. 



O. de Flore : Atti. Ac. Sci. Nap., vol. xv, 1913 (contains bibliography) ; Rend Ac. Sci. 

 Nap., vol. xix. 1913, p. 106. 



6G. Mercalli : Vulcani Attivi, Milauo, 1907, p. 207. 



