174 cosmos. 



activity of volcanoes. They have lately been called Pla- 

 tonic, in opposition to the true Volcanic earthquakes, which 

 are usually limited to smaller districts. In respect of the 

 more general views of Vulcanicity, this nomenclature is, 

 however, inadmissible. By far the greater part of the earth- 

 quakes upon our planet must be called Plutonic. 



That which is capable of exciting earth-shocks is every 

 where under our feet ; and the consideration that nearly 

 three fourths of the earth's surface are covered by the sea 

 (with the exception of some scattered islands), and without 

 any permanent communication between the interior and the 

 atmosphere, that is to say, without active volcanoes, contra- 

 dicts the erroneous but widely disseminated belief that all 

 earthquakes are to be ascribed to the eruption of some dis- 

 tant volcano. Earthquakes on continents are certainly prop- 

 agated along the sea-bottom from the shores, and give rise to 

 the terrible sea-waves, of which such memorable examples 

 were furnished by the earthquakes of Lisbon, Callao de Lima, 

 and Chili. When, on the contrary, the earthquakes start 

 from the sea-bottom itself, from the realm of Poseidon, the 

 earth-shaker (oeiolxOov, kiv?jocx^<^ v ), and are not accompa- 

 nied by upheaval of islands (as in the ephemeral existence 

 of the island of Sabrina or Julia), an unusual rolling and 

 swelling of the waves may still be observed at points where 

 the navigator would feel no shock. The inhabitants of the 

 desert Peruvian coasts have often called my attention to a 

 phenomenon of this kind. Even in the harbor of Callao, and 

 near the opposite island of San Lorenzo, I have seen wave 

 upon wave suddenly rising up in the course of a few hours 

 to more than 10 or 15 feet, in perfectly still nights, and in 

 this otherwise so thoroughly peaceful part of the South Sea. 

 That such a phenomenon might have been the consequence 

 of a storm which had raged far off upon the open sea, was 

 by no means to be supposed in these latitudes. 



To commence from those commotions which are limited 

 to the smallest space, and evidently owe their origin to the 

 activity of a volcano, I may mention, in the first place, how, 

 when sitting at night in the crater of Vesuvius, at the foot 

 of a small cone of eruption, with my chronometer in my 

 hand (this was after the great earthquake of Naples, on the 

 2Gth of July, 1805, and the eruption of lava which took 

 place seventeen days subsequently), I felt a concussion of the 

 soil of the crater very regularly every 20 or 25 seconds, im- 

 mediately before each eruption of red-hot cinders. The cin- 



