San Marcos free press. [volume] (San Marcos, Tex.) 1877-1892, 1883-05-31
The Provision OF Thunder s,o,,...

| uor storms,
Considering the immense destn,,
iveness OF thunder storms at this ~
son, a recent communication % v.
tire by Mr.. Ley, Of London, on va va
subject Of "sheet lightning" is nr %e
teal and timely. The p6enomss,na"S.''
of "sheet lightning" has been IoUti
discussed by scientists, but its na,n1ss
has only within few years been ~
termined, and q too popular imnr NC
sion exists that it is a harmless erS;'
bition of electrical force in the clonds
1t is probably owing to this miscon'
ception that so many lives are lost Nv
lightning stroke, people generally No,
taking the noiseless electrical dispIsv
as the forewarning of a thupSs,
storm. Mr.. Ley very properly rejects
the notion that sheet lightning i
merely "a distinct form Of ightpina
unaccompanied by sound" and shows
that, on the contrary, as a rule, il il
"the illumination produced by a dis.
tant thunder Storm" 1T is certain"
he says, "that the Examinations Of an
ordinary thunder storm at midnight,
when there is no moonlight, have an
average radius of more than fortv
miles"
This is a moderate estimate, as
other experienced observers give much
greater distances at which Lightning
ia visible. Mr.. Symons states his be.
lief that it is sometimes visible "as
far as one hundred and fifty miles,"
which may possibly be the case in the
tropics, where electrical storms in
which the lightning flashes extend
over several miles, are formed at
great attitudes. The distance at
which thunder is audible, however,
does not often reach fifteen miles,
though an extreme case has been re.
liably reported in which over two
minutes elapsed between the flash
and the thunder, indicating that the
former took place about twenty-five
miles from the observer. 1t is obvious
that during the raging of an electrical
storm, it's vivid flashes, especially at
night, in the absence of moonlight,
may be seen at many points where
the thunder is inaudible, and also at
many points over which the storm it.
self will not sweep. But to all
places lying in the storms path and
at which the silent lightning isvisible
the flashes will serve as warning sig
mails of the tempest's approach.
With a little reflection, when such
signals are displayed to an observer,
it is easy to foresee whether the dis
tant storm will pass dangerously near
him. While our summer thunder
storms may not be translated from
point to point in the same way reg
l1lar cyclone is, they progress so
slowly that there is usually time
enough between their frstseen flashes
and their near approach to discover
their line of advance and to guard
against the danger. Of course, this
interval is greater if the storm comes
up at night, when its lightning can be
seen at greater distances, probably in in
,,oct ooCoc o,,o or two hnurs before 1t
arrives. AS all great thunder storms
occur only where sudden and sharp
alterations of temperature are I'M
pending, and the daily weather reports
show generally over what sections
such thermal chang will take place,
every man may be weather prophet
enough to put the above principles to
good use in protecting his family ano
his property against the disastrous
effects of these storms.