Sect VII.] 



EARTHQUAKE PHENOMENA 



«l 



^ 



kr 



I -.. 



. i 



Jr. 



r 



m 



4 {ae 



b 



iV 



^ 



! 



■^ 



ft 



L " 



J 



.^1 



ible. 



^f 



t» _ 



r 



^ 



•^ ^' 



f 



'3. 





«Ui' 



Vfi^ 



ft 



works, to enable them the better to grasp beforehand 

 the subject of earthquakes:- — Lyell's ^Geology/ passim; 



Doiomieu's 'Account of the Great Earthquak 



theoretic views ; Hers 



r^ 



Cit JYi i ■'■a ' O, 



bria/ neg 



his 



j: 



:\rt. 



) 



'Tides' C 

 ' Report on 



Waves. 



dia Metro- 

 Brit. ASBO., 



1844; Mallet's 'Dynamics of Earthquakes/ Trans, Royal 

 Irish Acad,, 1846 ; Hopkins's ' Report,' Trans. Brit, Ass^, 

 1847-48, and the several narratives of earthquakes. 



It sometimes happens that a shock of earthquake is felt 



at sea, at gi'eat distances from land, and over profound 



depths ; a sudden blow is felt, as if the ship had struck 

 a rock. 



The earth- wave emerging from an origin closely beneath, 





is here transferred to the ocean, through which it p 

 upwards as an elastic wave, wdth the same speed as the 

 sound-wave through the sea. When such an event occui's, 

 and circumstances are favourable, we should look out for 

 the passage almost immediately in form of a single, low 

 swell, of the great sea-wave, which may be formed directly 



over the origin, at no very great distance off. A cruise 



about and soundings may be made in search of indications 

 (piunice, &c.) of the ori 

 be indicated by the degree of lateral stroke felt at the 

 moment of the shock and by the direction of the great 



sea 



■ «i 



S' 



- 1 



t 



^ 



k- 



•N 



