The sun. [volume] (New York [N.Y.]) 1833-1916, 1915-03-21
the process Is clearly understood by


which they condense to form planets.
IL in fact such condensation takes
place.
Continuing the discussion of tenn
pcratures below tho surface he sets
forth the fact that our knowledge Of
subterranean heat is derived from "A
very few points of deep observation.
that tho deepest of such points is only
one four-thousandth part OF the
earth's radius. Any curve OF temper
atures from the few underground OBJ
servations which we have must We
highly artificial and at most carries
us to no more than rs deg. G. Be
yond this vertical distance toward tho
central mass. higher than this degree
" heat, which Is appreciably below
the boiling point OF water at the SUR
face. any opinions as to temperature,
he remarks, must be purely specu,a-
tive extrapolations on an imaginary
curve. Against this Is to he set the
fact that recent careful determine
lions of lava temperatures in active
volcanoes at the surface where they
have been already cooled by passage
through Cold rocks and are subject at
once to radiation into cooler atmos-
phere have set forth the existence Of
temperatures Of 100 deg. G.. and pos
sibly 1000 deg. &. We note while on
The theme that lie seems not to have
had access to the recent heat deter
limitations conducted by Jaggar and
his party with extreme difficulty In the
fire pit OF kilauea. As a physicist ~
tho Earth hp nnipfc nttf M nrrnr Ia
astronomical theory bearing upon this
matter OF earth temperature. "As to
the opinion commonly held that the
earth was once liquid like the sun, a
nebular hypothesis AS to it's origin
does not necessarily demand Il, and
there Is no evidence upon the surface
Of the earth itself that 1t was ever in
a liquid condition. There are no rocks
exposed which could he considered as
originally solidified portions OF a once
liquid globe. and its spheroidal shape
is consistent with the assumption OF
It's present rigidity."
In these lectures i was not the plan
OF Dr. Tddings to essay the solution OF
volcanic phenomena. for that our
knowledge does not yet suffice. Ills
aim has been TO state the problem
which must be solved, to set forth the
various hypothesis and to examine
their arguments and TO extract the
! insoluhle objections. The great prob
lem is the souiCe Of the molten rock
matter which is discharged through
tho volcanic ducts. the cause Of its
heat exceeding the critical temporal
! turc of rock. In y final summary Ne
presents Il statement which is at least
! indicative Of the line which he expects
future study to follow toward proof -.
the complex and irteracting causes.
Prom Astronomical and g~coioGi-
cal considerations il appears that the
earth is To he thought Of as "A soli0
body having nearly twice the riEidity
of steel: the outer one possibly some
what over thirty miles thick. haVin-
a r.sidity like that If plate glass. The
density of the central portion must hC
considerably greater than that ui the
utter rocky zone. the lithosphcrc, ana
may consist mostly Of iron Will
smaller amuuItS of other constituents
that occur in rocks. In order 10 main
tain the iigid!ty IT the globe II Gems {,
W 70 49, ~ ~ iHEAAlil' 'AAtN't NAA'N 49,
temperature T. not high enough +,
convert the materials into liquids q,
that tho effect Of high temperature |!
offset 10y that of pressure. Hut the %,
iects g moderately high pressure ~
the NiScp~ity of rock substances are
probably much less than tho effect u
high temperatures. So that very hIEi
temperatures seem to hc~ prcc.udedf iron
consideration. 1t Is possible that IN,
balance between the effects ~ temper,
aturc and pressure il such tia ther,
may he a 2pnc beneath the f%rangihl'
portion Of the atmosphere which may
behave toward sudden stresses a,
though Ii We're rig Il, but may az
under prolonged strain like a high,
vlscous liquid. Tbs pseudo-rig.d Zon
: may hc the source of ignruus roCi
magma. which may shift It's position il
consequence of warping Of the ltho
sphere; and when a proper system %
stresses permits may flow hetweer
parting wills and rise into hich"
horizons"
The magnitude e volcanic activit,
j. commonly measured too high b,
reason OF the Introduction Of the hu
man factor. An eruption of Nesuviu
which hur.es rumpci and Herculan
cum, puny works Of man; an outbreal
OF Pclec taking great tol, Of man an.
the things which he has made: tn
crash If l~<rakatau which seems ::
rcnd the earth apart-all these bull
BIG. Yet these are local. The sensi
tive s~eismometer shows for the great
est of them but the faintest trcmo
of h rock crust, nothing at all com
parable to the CULVER which the Who'll
globe u~udcrgoes when faulted roc
surfaces slip by hut Il few milimotar,
as AZ san Francisco. In the opinion Il
pr. lddings volcanic activity has pro
duc"d local notifications If the ter
rain, the great formative movement
which have produced continents an
the deeps Of the sea have been due I
i. tho warping Of the crust in which Law
c~Xtruslon has been a result rathe
than an impulse.
Russia To-day and Tomorrow.
> What is the truth about Russia? |
she to-day strong, united, hopeful fu
tho fufurp or ~ sho tln Same iDer