348 ELECTRIC RESONANCE OF MOUNTAINS. 



Btrnck against one another on being alternately attracted and repelled Ly elec- 

 tricity ; but it appears to me to proceed unquestionably from a sort of crepitation or 

 crackling of electricity escaping througli the asperities of the stony surface. 



A third observation of the same kind we owe to M. Craveri, who was sur- 

 prised by the same meteor near the summit of Popocatepetl, September 15, 1855, 

 with this difference, that the incident taking place on fields of snow, the noise 

 of the crepitation of the ground was not produced. 



The following are the analogous facts which have come to my knowledge : 



In 1767 H. B. de Saussure visited the top of tlio Brevent in company with 

 Pictet and Jalabert.* The travelers were there directly electrified to such an 

 extent that on stretching out tlieir hands they experienced prickings at the end 

 of the fingers ; the electricity escaped from them with a kind of thrilling sensation. 

 Sparks, it was found, might be drawn from the button of a gold band which 

 surrounded one of their hats, and also from the iron end of a mountain staff. 

 These effects were attributed to a great storm-cloud which occupied the middle 

 region of Mont Blanc, and which gradually extended itself above the Brevent. 

 At a dozen toises below the top of that mountain the electricity was no longer 

 perceived. The storm raged around iMont Blanc, but on the Brevent there fell 

 only a light rain of short duration, and then the disturbance was dissipated. 

 From this recital it is easy to see that the storm did not prevail upon the Brevent 

 at the moment of the observation, since there was no rain falling; but that, at 

 this point, the electricity discharged itself in a continuous current by the summit 

 of the mountain. 



In 1863, M. Spence Watson, visiting, with some guides the Col de la Jung- 

 frau, was overtaken by a hurricane, attended with hail and snow. The staves 

 commenced their peculiar chant ; the expeditionists experienced sensations of 

 heat in different parts of their bodies, t especially the head, and the hair stood 

 erect ; a guide took off his hat, exclaiming that his head was burning ; a veil 

 was kept stiff and straight in the air. Electric currents, at the same time, 

 escaped at the ends of the fingers. Claps of thunder (in the distance, for no 

 lightning was seen) for an instant interrupted the phenomenon. Finally, shocks 

 were felt, and M. Watson had the right arm paralyzed for some minutes. This 

 arm continued for several hours to l)e the seat of acute pains. | During this 

 time the snow fell tvhistUng like hail.^ But what is most remarkable was the 

 emission of a noise by the snow, a crackling similar to that of a brisk shower 

 of hail, evidently the analogue of that which the ground of the Nevado de Toluca 

 emitted in the observation above described. The phenomenon lasted 25 minutes. 

 It had no unpleasant consequence, except a burning in the faces of the travelers 

 as if they had been exposed to the sun on the snow. 



M. Forl)es, while crossing by St. Theodule, heard the chant of the staves, and, 

 in July, 1856, M. Alizier, of Greneva, witnessed the same phenomenon near the 

 summit of the Oldenhorn, when the sky was overcast and a stoma was imminent, 

 which btirst forth an hour afterwards and ivas mingled ivitk hail.\\ We will not 

 speak of the stonn during which Colonel Buchwalder and his aid were struck by 

 lightning on the Sentis. for there the phenomenon was of a difierent order and 

 falls rather within the category of the thunderbolt. 



But the nocturnal illumination of rocks pertains probably to the phenomenon 

 of electric efilux from culminant peaks. M. Fournet cites, on this subject, the 

 striking luminosity of the rocks of the Grands-Mulets (Mont Blanc), observed 

 by M. Black wall, on the night of August 11, 1854, and which was accompanied 



* Voyage dans les Alpcs, touie, ii. 



t Tlii.s sensation of heat seems to me to be of the same kiud with the paiu which I expe- 

 rienced in the back. 



t Alpine Journal, September, 186H. 



^ Probably snow resembling rice, a sleety shower. 



II See the note of M. C. M. Briquet, (Kcho dcs Alpes, 1865, No. 4.) Sur les ph6nomenes 

 ileciritiues qui accompagnent les orascs d dcs grandcs altitudes, where these observations are 

 collected and compared. Geneva, 18(55. 



