XIV LINES OF VIBRATION 329 



readiness, according as their direction more or less nearly 

 coincides with the line of the waves. The fissures in the 

 ground generally, though not uniformly, extended in a S.E. 

 and N.W. direction, and therefore corresponded to the lines of 

 undulation or of principal flexure. Bearing in mind all these 

 circumstances, which so clearly point to the S.W. as the chief 

 focus of disturbance, it is a very interesting fact that the island 

 of S. Maria, situated in that quarter, was, during the general 

 uplifting of the land, raised to nearly three times the height of 

 any other part of the coast. 



The different resistance offered by the walls, according to 

 their direction, was well exemplified in the case of the Cathedral. 

 The side which fronted the N.E. presented a grand pile of ruins, 

 in the midst of which door-cases and masses of timber stood up, 

 as if floating in a stream. Some of the angular blocks of brick- 

 work were of great dimensions ; and they were rolled to a 

 distance on the level plaza, like fragments of rock at the base 

 of some high mountain. The side walls (running S.W. and 

 N.E.), though exceedingly fractured, yet remained standing ; 

 but the vast buttresses (at right angles to them, and therefore 

 parallel to the walls that fell) were in many cases cut clean off, 

 as if by a chisel, and hurled to the ground. Some square 

 ornaments on the coping of these same walls were moved by 

 the earthquake into a diagonal position. A similar circum- 

 stance was observed after an earthquake at Valparaiso, Calabria, 

 and other places, including some of the ancient Greek temples.^ 

 This twisting displacement at first appears to indicate a vorti- 

 cose movement beneath each point thus affected ; but this is 

 highly improbable. May it not be caused by a tendency in 

 each stone to arrange itself in some particular position with 

 respect to the lines of vibration, — in a manner somewhat 

 similar to pins on a sheet of paper when shaken ? Generally 

 speaking, arched doorways or windows stood much better than 

 any other part of the buildings. Nevertheless, a poor lame 

 old man, who had been in the habit, during trifling shocks, of 

 crawling to a certain doorway, was this time crushed to pieces. 



I have not attempted to give any detailed description 

 of the appearance of Concepcion, for I feel that it is quite 



■^ M. Arago in Uhistiliit, 1839, p. 337. See also Miers's Chile, vol. i. p. 392 ; 

 also Lyell's Principles of Geology, chap. xv. book ii. 



