and especially in Scotland. 305 



precisely similar indications. Reference has already been made 

 to Humboldt*s authority, that his electrometer was strongly 

 affected during the earthquake of Cumana in November 1799. 

 In like manner, during the Pignerol earthquakes, before al- 

 luded to, it is stated that, on the 10th April 1808, during 

 a shock, the electrical apparatus was considerably affected. 

 The following remarks in the same report are especially wor- 

 thy of attention : — " Quand I'intervalle des secousses depas- 

 soit plusieurs heures, I'electricite se truovoit de peu de degr^s, 

 et toujours positive ou vitree. Dans le moment des secousses, 

 elle devenoit forte au point de ne pouvoir plus etre mesuree 

 par les electrometres. Vingt minutes apres une secousse, les 

 bandalettes de mon electrometre, mis en contact de I'appareil 

 electrique permanent que j'ai etabli a la Tour, restoient en- 

 core a 30° de divergence toujours positive." * Signor Gem- 

 malaro relates, that his guide and two travellers on Mount 

 Etna, in June 1814, encountered such a current of electricity, 

 that their hair bristled up from the effect of it, and a loud 

 whistling or humming sound in the air was heard, and which 

 they modulated by motions of their fingers. In extracts from 

 Gemmalaro's Journal^ referred to below, many other electrical 

 phenomena are mentioned, in connection with eruptions of 

 Etna.t Mr Drake, in describing the Cincinnati earthquakes, 

 which commenced in December 1811, says, that, *•' in the win- 

 ter of 1811--1812, many persons observed, or thought they 

 observed, that those substances which are susceptible of electric 

 excitation, gave extraordinary indications of the presence of 

 the electric fluid.^J 



After it has thus been established that electricity, to an 

 unusual extent, is connected with earthquake-shocks, there is 

 naturally a disposition immediately to inquire, whether the 

 one phenomenon is directly or indirectly the cause of the 

 other ? But the inquiry might be extended so as to compre- 

 hend all the other phenomena before related, which appear to 

 be equally connected with the occurrence of shocks. It is bet- 

 ter, therefore, to postpone any attempt to explain these isolated 

 phenomena, important though they be, until the whole subject 



* Journal do Physique, tomo Ixvii. 



t Brande's Journal of Science, vol. xiv. p. 324, and xix. p. 233, 



X Account of Cincinnati, 1B15; p.2 39. 



