October 7, 1897] 



NA TURE 



545 



When the outbreaks do occur they are usually very 

 severe, and streams of lava pour down the sides of the 

 mountain, devastating forests, vineyards and fields. 

 Huge boulders, sometimes a cubic yard in volume, are 

 also thrown up. 



Winter 

 Spring 

 Summer 

 Autumn 

 The year 



Fig I.— The Etna Observatory. 



The position of the observatory is as follows : 



Altitude 2942 metres. 



Latitude 37° 44'"3 



Longitude (East) 2° 33'-8 (Rome 



j The temperature at the summit ought to be 2'-2 lower 



I than that at the observatory, but observations have 



! shown that it is o'"6 greater, owing doulnless to the heal 



: of the crater. 



Fig. 2.— Showing the front of the Observatory near the summit of the mountain. 



It IS situated one kilometre from the central crater, and 

 on the southern side (Figs, i and 2). Meteorological ob- 

 servations made since 1892 have given the following mean 

 results : — 



NO. 1458, VOL. 56] 



Thunderstorms on Mount Etna are not common, and 

 occur chiefly in the autumn. There is no lightning con- 

 ductor fixed on the observatory, and up to the present 

 time the latter has never been struck, although the large 



