164 EARTHQUAKES. 



In none of the cases here quoted was any disturbance 

 of the water observed. 



The great earthquake of Lisbon was felt by vessels on 

 the Atlantic, fifty miles away from shore. 



On February 10, 1716, the vessels in the harbour of New 

 Pisco were so violently shaken that both ropes and masts 

 were broken, and yet no motion in the water was observed. 

 Some have described these shocks like those which would 

 be produced by the sudden dropping of large masses of 

 ballast in the hold of the vessel. Other cases are known 

 where rigging was damaged, and even cannon have been 

 jerked up and down from the decks on which they rested. 



Cause of vibratory blows. — From the rattling sound 

 which has accompanied some of these submarine shocks, 

 many of which, it may be remarked, have never been re- 

 corded as earthquakes upon neighbouring shores, it does 

 not seem improbable that they may have been the result 

 of the sudden condensation of volumes of steam produced 

 by submarine volcanic eruptions. 



As confirmatory of this supposition we have the fact, 

 that many of the marine disturbances which might be 

 called ' sea-quakes,' have been observed in places which 

 are close to, or in the line of, volcanic vents. Thus, M. 

 Daussy, who has paid special attention to this subject, bas 

 collected evidence to show that a large number of shocks 

 have been felt by vessels in that portion of the Atlantic 

 between Cape Palamas, on the west coast of Africa, and 

 Cape St. Koque, on the east coast of South America.^ 



Some of the vessels only felt shocks and tremblings, 

 but others saw smoke, and some even collected floating 

 ashes. In considering the submarine shocks of this par- 



' M. Dauspj, * Sur I'existence probable d'un volcan sousmarin situ6 

 ar environ 0° 20' de lat. S., et 22° 0' de long, ouest,' Comjptes RenduSf 

 vol. vi. p. 512. 



