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. 1 
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 
1 M. Arago in LTnstitut , 1839, p. 337. See also Miers’s Chile , vol. i. p. 392 ; 
also Lyell’s Principles of Geology , chap. xv. book ii. 
