s of the earth's interior.

"The earth," he said, "is in a condition of unstable equilibrium so
far as its insides are concerned. The outer crust is solid, but after
you get down sixty or seventy miles the rocks are nearly in a fluid
condition owing to great pressure upon them. They flow to adjust
themselves to changed conditions, but as the crust cools it condenses,
hardens, and cracks, and occasionally the tremendous energy inside is
manifested on the surface.

"When the semi-fluid rocks in the interior change their position there
is a readjustment of the surface like the breaking up of ice in a
river, and the grinding causes the earthquake shocks which are
familiar in various parts of the world. The earthquake at San
Francisco was probably local, although the center of the disturbance
may have been thousands of miles away from that city."

Prof. Willis L. Moore, the chief of the weather bureau, in talking of
the records of the earthquake in his department, said:

"We have a perfect record of this earthquake, although we are
thousands of miles away from the actual tremor itself. There were
premonitory tremblings, which began at 8:19 and continued until 8:23
or thereabout. Then there was severe shock which threw the pen off the
cylinder.

"According to our observations here there was a to and fro motion of
the earth in the vicinity of Washington amounting to about four-tenths
of an inch at the time of its greatest oscillation. These movements
kept up in a constantly decreasing ratio until nearly half an hour
after noon.

"San Francisco may have been a long way away from the real earthquake
and merely have been within the radius of severe action so as to
produce disastrous results. It is quite likely, in fact, that the
greatest disturbance may have taken place beneath the bed of the
Pacific Ocean.

"If it resulted in an oscillation of the earth of only a few inches
there would be no likelihood of a great tidal wave. If, however, there
was produced a radical depression in the bed of the ocean, the sinking
of an island, or some other extraordinary disturbance, a tidal wave
along the Pacific Coast would almost certainly be one of the events of
this great disaster.

"There are apparently three distinct weak spots in the United States,
which are peculiarly subject to earthquake shocks, and we are likely
sooner or later to hear from all of them in connection with the shock
at San Francisco. There is one weak area a