, 1913-08-09

system is called the "hour meridian system
and is an absolute necessity for the United
States. Tue same system is applied III
Porto Rico, which is a little too far east to
be included in the 18th meridian time and
is therefore placed under the time of the
6Oth meridian. Hence, when we read that
the recent earthquake occurred at Ponce
and San Juan at 5 o'clock it means that 1T
occurred at those places at five o'clock ac-
cording to Goth meridian time. Now the
Danish Islands lie on the 65th meridian
or five degrees to the West, which at four
minutes to the degree gives us twenty MN
utes, hence the earthquake occurred III
Ponce and San Juan at twenty minutes to
five according to St. Thomas time.
AS the shock occurred here in st. Croix and
in 81. Thomas at 4 80 am, the above would
seem to imply that it was moving from east
to west: but tue fact that it afterwards shook
s.. Kits and Point-a-Pitre at a later hour
would seem to show that in reality 1T
was moving i'll the contrary direction,
that is to say past us from ABOUT
west to east. The shock was felt at
ST. Kits Ut 5 o'clock am, local time for that
island, and "a the meridian OF st. Kits
lies about 24 leg. east of that of St. Thorn
as, 5 o'clock local time at ST. Kits be-
comes 45l local time in St. Thomas.
Assuming that the time given for the occur
renee of the earthquake at St. Thomas is
true local time and that the same may be
said for the local time at St. Kits, we tlnd
that the shock passed from Christian
sted to st. Kits, a distance OF about
I2O Eng miles, in 81 minutes, which
would mean that it travelled at the
rate of about 81 miles q minute, or about
500 fit. per second. This result depends on
- a..aa e AZ. lDo,l TINA of ST Thomas
aud ST. kits, failing which the rate calcu-
lated would vary according to the nature and
extent OF the errors in stating the local time.
This uncertainty makes it difficult to find a
theory which would explain the observed
flrts.
The difficulty appears again when we con-
slider the reported time of the shock reach
ing Point Il Pitre, namely 5.5 q. m. AS
the meridian of Point a Pitre lies about 81
degrees East of the meridian of st. Thomas
tie time given for that place converted into
st. Thomas time gives 4.51 a. ID. that is to
say the same as for ST. Kits.
With the shcck travelling east southeast in
that pant of It's extension this would be lmpos-
sib e, so that it would seem either that the
clocks were wrong or that the Point a Pltre
shock depended on a separate movement,
which is hardly likely.
As 1t Is impossible 10 get any lnIormaCloh
on these time questions we have to leave
them. 1t seems to US likely that what hap
pened was about as follows: the central con-
cussion. however caused, winch produced the
tremors, was under the sea to the southeast
Of Porto Rico, whence the waves in the rocks
spread out in all directions. These reached
Ponce, San Juan, st. Thomas, and st. Croix,
which all stand around the supposed centre
in a semicircle towards the North, at approx
imately The same time, after this they con-
tinued to spread, and at about the time stated
above were felt in st. Kits and Guadeloupe,
lying to east southeast OF our island. If this the
DRY is correct the earthquake would continue
to extend itself in other dir ections around rs
but no tidlDgs of this fact have been received,
partly because a good part of the space in
question lies under The sea and partly be-
cause the shock was becoming more feeble
as it proceeded and would therefore escape
notice or be thought too trivial to report.