The Hawaiian gazette. [volume] (Honolulu [Oahu, Hawaii]) 1865-1918, 1884-09-10

IS TeDehbeu. All Tue uOlSleSb explosions
which l have heard on Hawaii have been
undoubtedly produced by compressed and
heated air.
With regard to the statement so often
made respecting steam escaping from Ha-
waiian molten lavas, have a letter by me
from the late Mr.. Coan, of Hilo-whO per
haps saw more running lava in his lifetime
than any other man ever did-in answer
to my inquiries ON the subject, in which
he states his belief that steam is never seen
coming from Hawaiian lavas except when
they clearly come in contact with water,
and then the steam comes from the water,
not from the lava. From the or1fices of
eruption, he says he has often seen steam.
and then he observes: I'VE may be sure
that fire and water are in contact below
The late Mr.. Poulet Scrope, in his work on
volcanoes, made serious mistake in quot
ing Mr. Coan in aid of the mixed steam
and lava hypothesis, in which he makes
him say, that from the surface of the lara
current of the eruption of 1852, the steam
rose in Aeecy wreaths towards heaven"
Mr.. Coan was only describing the rise of
great volumes of steam from the pools of
water as the lava poured into them in its
almost daily near Hilo in 1881.
Professor Dana refers to the hanging
cloud constantly seen over Kilauea, as
proof that steam escapes in large quaint
ties from the Kilauea lavas, and that this
cloud often .condenses and falls in rain.
Much steam from percolating water no
doubt arises from assures all about Kilauea
and when it rains hard, from all the hot
places, and from the surface of the lakes,
and it usually blows away very quickly
But l attribute the hanging cloud to diff
ferent cause simply to that of all hanging
clouds-the heated column of air over HI
lauea absorbs and retains an excess of
moisture in an invisible state, it rises by
its less specific gravity into cooler stra-
tum and there condenses. The hanging
clouds on the windward side of all our
mountains are merely another phase of the
same principle. l have two oil paintings
executed by Mr.. Furneaux, of a remark
able cloud which hung for long time over
that part of the 1881 flow, to the eastward
of Hilo where the lava had got damned
up at the edge of the woods aud remained
for long time as large half-tholten lake
This cloud not only dropped rain, but one
IL
ceeding from it, and when the lower end
of it touched the hot lava it was sent his
sing of again in steam. Now Iwould APP
peal to any observer of the lava flow of
1SSO-1SS1 they were numerous
whether in this situation and away from
any cracks, assures, or orifces of eruption,
there was any such amount of steam pro-
eeediRg from the Ldra, or from any orifccs in
that neighborhood, as could have pro
duced that constant hanging cloud, highly
charged with vapor. A rising column
however, of moist Hilo atmosphere heated
over the molten lake and therefore contin-
ually rising into cooler stratum must pro
duce hanging cloud, by the condensa-
ton of the excess of moisture held by the
heated air. 1t may well have produced
water-spouts, for such cloud would soon
become super saturated and tend to fall in
vortex ring. This cloud was no doubt
assisted, blackened and intensified by the
smoke and vapors from the burning woods
around the edges of the constantly ad-
yancing lava lake.
For my part L closely watched the lava
flow of 1859, and walked upon the "a
bank as the molten river ran down
the center, saw it afterwards fall into
the sea at the coast l have watched
the layas in the lakes of Kilauea. in
the fountain of 1873 in the summit era
ter, and in the flow of 1881 near Hilo, and
l have never been able to detect steam
coming from, The laed, although l have
looked for it. Steam from the ocean and
from the pools of water that the lava ran
into, from the oritices of eruption, from
cracks and assures in the neighborhood
of the hot rocks near Kilauea and else
where, from the trees and the Jungle from
which the lava was evaporating the juices,
from the rain that has poured on to it,
have seen in abundance, but coming from
the lava itself | have never happened to
detect it. Perhaps others have been more
fortunate. Why is it necessary, however,
to imagine the cells in our lavas to be the
result of steam, when air gives such a sim
pie account of them?
But there is still another phase in the
behavior of our lavas, for which steam is
constantly brought forward as the origin,
and Capt. Dutton seems inclined to follow
the usual Interpretation mean the hol-
times cover, in close succession, hundreds,
perhaps thousands of acres of ground.
He observes:
THE numberless mounds or bosses of
pdhoehoe were all formed in detail in the
manner already described, by repeated
outshoots of streamlets from beneath the
hardened crust behind. As these belches
of lava cool they exclude the occluded
steam, and the mass swells up by the
formation of myriads of vescicles, and
often by the formation of great hollow
blisters underneath"
Having watched the formation of these
mounds of pdhoeEoe in 1859 and in 1881, it
did not appear to me that steam was con
cerned in the process. They seemed to
be a simple hydrostatic effect in liquid
of which the crust cools rapidly. A Wis
cous liquid usually tends to flow, if some
what slowly released, in fattened spher-
oidal masses, as porridge does, or on a
smaller scale like quicksilver The rapid
cooling and stiffening of the crust, fixes,
as it were, these fattened spheroidal
masses, and the molten lava flowing from
the "a bank, or from somewhat higher
level behind, and protected by the crust
from radiation, pours into the rounded
mass under a small head of pressure, and
swells it out while the crust is somewhat
plastic. But now two things occur, the
crust gets sitter and the head of liquid
inside gets higher A break has to occur
somewhere under the head of liquid pres
sure. This naturally happens at the low
est side, the molten lava belches out again
and forms another mound alongside but
little lower down the slope And so the
process goes on. The molten lava often
runs all out of the mound, leaving the
hardened hollow dome, just as it runs out
of the arched stream, leaving the crust
with a tunnel underneath. Sometimes
the contraction of the cool crust of the
domes, causes the center piece of the top
to crack in a rudely pentagonal or hexag-
onal shape and to fall in, but sometimes
it remains entire. In my view, if there
were no water, steam, air or elastic gases
in the planet, these domes would form
essentially as they appear, while the Ha.
waiian eruptions and fountains of lava
might continue to spout as they do to-day.
The whole seem to be simple hydrostatic
effects, the result of liquids endeavoring
to find the level due to their density.
There is this peculiarly about these Ii
guilds, however, namely, that the slightest
cooling makes them first viscid, then sol
id, so that they do not always respond as
freely to changes of level as ordinary Ii
guilds do, especially in narrow and crooked
passages, or when exposed to radiation.
From this cause, also. they exhibit the