484 Mr. C. Tomlinson on the Weathering of Rocks, 



nous column was seen to descend in the direction of Chate- 

 lard, and it is stated that the electricity could be distinctly 

 heard as it ran from point to point of an iron railing in the 

 cemetery. None of the persons referred to were hurt, they 

 only complained of an unpleasant sensation in the joints as if 

 they had been violently twisted, a sensation which lasted for 

 a few hours. 



A highly electrified condition of the atmosphere may thus 

 produce either the glow- or the brush-discharge. Professor 

 James Forbes, while engaged in his remarkable study of the 

 glaciers of Switzerland, relates that on one occasion near 

 Mont Cervin, the atmosphere being very turbid and the 

 ground covered with half-melted snow, while about 1500 feet 

 below the Col and about 9000 feet above the sea, he noticed 

 a curious sound which seemed to proceed from the alpenstock 

 with which he was walking. He says: — "I asked the guide 

 next me whether he heard it, and what he thought it was. 

 The members of that fraternity are very hard pushed indeed 

 when they have not an answer for any emergency. He 

 therefore replied, with great coolness, that the rustling of the 

 stick no doubt proceeded from a worm eating the wood in the 

 interior ! This answer did not appear to me satisfactory, and 

 I therefore reversed the stick so that the point was now upper- 

 most ; the worm was already at the other end ! I next held 

 my hand above my head, and my fingers yielded a fizzing 

 sound. There could be but one explanation — we were so 

 near a thunder-cloud as to be highly electrified by induction. 

 I soon perceived that all the angular stones were hissing 

 round us like points near a powerful electrical machine. I 

 told my companions of our situation, and begged the guide 

 to lower his umbrella, which he had now resumed and hoisted 

 against the hail-shower, and whose gay brass point was likely 

 to become the paratonnerre of the party. The words were 

 scarcely out of my mouth when a clap of thunder, unaccom- 

 panied by lightning, justified my precaution."* 



In a paper by H. de Saussure f it is remarked that the 

 lighting up of the rocks at night is analogous to the curious 

 fact of electricity moving over the prairies, as observed by 

 M. Quiquerex near Constamon. It may be compared to a 

 kind of lightning-discharge in miniature, resulting from the 

 electrified cloud brushing over the earth and discharging 

 itself by a thousand sparks coursing over the meadows. Saus- 

 sure then gives an account of his own observations during 



* ' Travels through the Alps of Savoy/ &c. 8vo., Edinb. 1843. 

 t Phil. Mag. 4th series, xxxv. p. 128 (1868). 



