The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1903-11-15
T~HUNDERLEsS LIGHTNING.
The Distant Storm Theory Does Not
Apply to 1t.
Baltimore American.

Baltimore American.
The so-called "heat-lightning," or sum-
mer lightning" has long been a matter of
controversy. The phenomenon in question
is the appearance of lightning without
thunder on pleasant summer evenings,
which was formerly asserted by almost all
authorities TO be the reflection of lightning
due to some very distant storm, but is now
quite generally regarded as analogous to the
brush or gov discharge of an electrical
machine. The probability seems to be that
these explanations will both hold in diff
ferent cases. Professor Geikie, the noted
geologist, writing to Nature from Murren,
Switzerland, describes an Alpine lightning
display which he thinks shows concIusively
that the distant-storm theory is ~inapplica-
BILE. He says:
Late in the afternoon wisps of white
mist began to gather round the summit of
the Jungfrau, ana streaks of this cloud
took shape in the higher air above the
great mountain ridge that extends from the
Silberhorn to the Braithorn. About s ID. m.
l noticed a faint quivering light overhead,
supplemented by occasional flashes of
greater brilliance and different color. These
manifestations rapidly increased in dis
unctness, and continued to play only along
the opposite mountain ridge, not extending
into the regions beyond, so far as these
could be seen from here, though 1 have since
learned that an independent series of flashes
was seen around the Schilthorn on this side
OF the valley. Not a single peal of thunder
was at any time audible. A long bank of
cloud formed at a higher level than the
submits of the mountain-ridge and at some
distance on the farther side of it, so that
the stars, elsewhere brilliant, were hidden
along the strip of sky above the crest.
As one watched the display, it was easy
to distinguish more definitely the two kinds
of discharge. One of them took the form
OF a family luminous reddish or pink light,
motion in horizontal beams that proceeded
APPARENTLY from left to right, as if their
back of the Jungfrau. These streamers so
closely resembled the aurora borealis that.
mad they appeared alone, one would have
ern lights had not here made an incursion
into more southern ATTITUDES.
The brighter discharges were not only
Tar more brilliant, but much more momen-
tary. They had a pale bluish-white color,
and came and went with the rapidly of ordi-
nary lightning. But they were clearly con-
nected with the mountains, and not reflec-
times they rose on the other side of the
great ridge, allowing its jagged crest to be
seen against the Illuminated surface of the
cloud beyond, but leaving all the precipiceS
and slopes on this side in shade. In other
cases they clearly showed themselves on
this side of the mountains, lighting up
especially the snow basins and glaciers
with the dark crags around them. Nothing
of the nature of forked lightning was OBJ
served among them. In one instance the
flash or horizontal band Of vivid light, a
mile or two in length, seemed to shoot up
ward from the slope at the base of the prec-
ipice Of the Silberhorn. as IL it sprang out
of the ground. having a sharply defined
fore reaching halfway up to the crest.
But the most singular feature of the more
brilliant white discharges was to be seen
when one OF the great couloirs of snow or a
portion Of a glacier remained for a minute
or two continuously luminous with a faint
~bluish-white light. After an interval the
same or another portion. perhaps several
miles distant, would CLEAN out in the same
way. My first impression was that this
radiance could only be a reflection from
some Illuminated part of the cloud. But 1
could not satisfy myself of the existence Of
any continuously bright portions of the
cloud. Moreover, the luminosity of the
snow and ice remained local and sporadic,
as If the beams of a searchlight had been
directed to one special part of the noun
tain declivity, and then after a while to
another. = The whole display afforded
an admirably complete demonstration of the
erroneousnesS of the notion formerly preva-
lent that summer lightning is only the re-
Election of distant ordinary lightning, and
of the truth of the more recent views as to
the nature Of the phenomenon.