172 COSMOS 



mathematically investigated. Attempts have been made to 

 reduce to a rectilineal* 17 standard the apparently circling 

 (rotatory) shocks of which the obelisks before the monastery 

 of San Bruno, in the small town of Stephano del Bosco 

 (Calabria, 1783), furnished such a well-known example. Air, 

 water, and earth-waves follow the same laws which are re- 

 cognized by the theory of motion, at all events in space ; but 

 the earth-waves are accompanied, in their destructive action, 

 by phenomena which remain more obscure in their nature 

 and belong to the class of physical processes, As such we have 

 to mention, discharges of elastic vapours, and of gases; 

 or, as in the small, moving Moya-cones of Pelileo, grit-like 

 mixtures of pyroxene crystals, carbon, and infusorial animal- 

 cules with silicious shields. These wandering cones have 

 overthrown a great number of Indian huts. 18 



In the general Delineation of Nature many facts are 

 narrated concerning the great catastrophe of Riobamba (4th 

 of February, 1797), which were collected on the spot from 

 the lips of the survivors, with the most earnest endeavours 

 after historic truth. Some of them are analogous to the 

 occurrences in the great earthquake of Calabria in the year 

 1783 ; others are new, and especially characterized l>y the 

 mine-like manifestation of force from below upwards. The 

 earthquake itself was neither accompanied nor announced by 

 any subterranean noise. A prodigious explosion, still indi- 

 cated by the simple name of el gran ruido, was not per- 

 ceived until 18 or 20 minutes afterwards, and only under 

 the two cities of Quito and Ibarra, far removed from Ta- 

 cunga, Hambato, and the principal scene of the destruc- 

 tion. There is no other event in the troubled destinies 

 of the human race, by which in a few minutes, and in 

 sparingly peopled mountain lands, so many thousands at 

 once may be overtaken by death, as by the production 

 and passage of a few earth-waves, accompanied by pheno- 

 mena of cleavage ! 



17 Mallet on vorticose shocks and cases of twisting, in Brit. Assoc. 

 Report, 1850, pp. 33 and 49, and in thf Admiralty Manual, 1849, p. 213 

 (see Cosmos, voL i, p. 199, Bonn's edition). 



18 The Moya-cones were seen by Boussingault nineteen years after I 

 saw them. " Muddy eruptions, consequences of the earthquake, like 

 the eruptions of the Moya of P^lileo, which have buried entire villages** 

 (Ann. de Chim. et de Phys. t. lyiii, p. 81). 



