Association of American Geologists and Naturalists. 343 
}, en Anaad j + hd ee 
distance passed over being about J . From 
this it would appear that the velocity was about thirty two miles per 
minute. If in like manner the times be compared when the earthquake 
was at Nashville, and again in a mean position between Columbia and 
Charleston, it will be found to have occupied in this part of its rapid 
march, about eleven minutes and eighteen seconds, but the distance 
being three hundred and eighty miles, the velocity indicated was nearly 
thirty three and a half miles per minute. So close an agreement of 
the two sets of results, bespeaks the accuracy of the data upon which 
these computations are based. ye 
_ In support of the above inferences respecting the direction of trans- 
mission of the earthquake, is the observed direction of the oscillating 
motion, which is described as having been at various localities from 
west to east. / pe ‘ 
_ The phenomena of the recent earthquake of Guadaloupe were next 
alluded to, as confirming in a remarkable manner the accuracy of the 
general laws of earthquake motion, deduced from the above described 
earthquake of the United States. — In the West India convulsion, the ve- 
locity of transmission was about twenty seven miles per minute, the 
pulsation being propagated laterally from an immensely elongated axis 
of disturbance, extending in a N. and s. direction, through the Wind- 
ward Islands, to Bermuda on the N., and to the coast of Guiana on the s. 
~ Respecting the origin of the wave-like motion of the ground in earth- 
quakes, some able writers have been disposed to consider it as the re- 
sult of a mere tremulous jar radiated from some deep-seated focus, or 
line of sudden fracture, and reaching the surface at points more and 
more remote from the source of disturbance. All the> circumstantial 
descriptions of the phenomena disclose, however, an essential and char- 
acteristic difference in the two motions, and plainly indicate the wave- 
ike motion to be an actual billowy oscillation of the earth’s crust. 
That the vibratory jar is not the cause, but itself the necessary conse- 
quence of the undulation, is apparent from the following considerations. 
A mere tremulous vibration transmitted along @ given column through 
the earth’s crust, would not sensibly elevate or depress: the surface, 
since the waves of compression and dilatation among the particles of 
the column, would neutralize each other in their effect on the dimen- 
‘sions of the mass. © It is difficult to conceive, moreover, how the broad, 
Bling Sound. But if-it were even practicable to account for the enor- 
mous magnitude of the low, broad waves into which the crust is thrown, 
