eston, on the Atlantic seaboard of Carolina.[7] At 9.51
a.m. of this day, the inhabitants engaged in their ordinary occupations
were startled by the sound of a distant roar, which speedily deepened in
volume so as to resemble the noise of cannon rattling along the road,
"spreading into an awful noise, that seemed to pervade at once the
troubled earth below and the still air above." At the same time the
floors began to heave underfoot, the walls visibly swayed to and fro,
and the crash of falling masonry was heard on all sides, while
universal terror took possession of the populace, who rushed into the
streets, the black portion of the community being the most demonstrative
of their terror. Such was the commencement of the earthquake, by which
nearly all the houses of Charleston were damaged or destroyed, many of
the public buildings seriously injured or partially demolished. The
effects were felt all over the States as far as the great lakes of
Canada and the borders of the Rocky Mountains. Two epicentral _foci_
appear to have been established; one lying about 15 miles to the N.W. of
Charleston, called the _Woodstock focus_; the other about 14 miles due
west of Charleston, called the _Rantowles focus_; around each of these
_foci_ the isoseismic curves concentrated,[8] but in the map (Fig. 37)
are combined into the area of one curve. The position of these _foci_
clearly shows that the origin of the Charleston earthquake was not
submarine, though occurring within a short distance of the Atlantic
border; the curves of equal intensity (isoseismals) are drawn all over
the area influenced by the shock.

As a general result of these detailed observations, Captain Dutton
states that there is a remarkable coincidence in the phenomena with
those indicated by the theory of wave-motion as the proper one for an
elastic, nearly homogeneous, solid medium, composed of such materials as
we know to constitute the rocks of the outer portions of the earth; but
on the other hand he states that nothing has been disclosed which seems
to bring us any nearer to the precise nature of the forces which
generated the disturbance.[9]

[1] The views of Mr. R. Mallet, briefly stated, are somewhat as
follows:--Owing to the secular cooling of the earth, and the consequent
lateral crushing of the surface, this crushing from time to time
overcomes the resistance; in which case shocks are experienced along the
lines of fracture and faulting by which the c