New-York tribune., 1899-07-30
HOW OLD is THE EARTH !?
KELVIN PUT 1T AT ABOUT TWENTY
MILLION YEARS
HIS ESTIMATE REVIEWED BY A CHICAGO opo1-
oGIsr-rHD QUESTION STILL OPEN.


attained condition of habitability is a question
recently revived by T. c. Chamberlain pro-
fessor Of geology at the University of Chicago
BE discusses the subject In Science" which had
. Few weeks previously republshed ar address
o. Lord Kelvin on the same topic This address
delivered in 1897. does little but reiterate views
EXPRESSED several times between 1862 and 1865
When Lord Kelvin, then Sir William Thorn
SCI. first took UP this problem it was with the
object Of showing the absurdity Of certain other
estimates made by geologists and biologists.
TIE latter believed that from one hundred mill
ION years to three hundred million years must
have passed while the rocks composing the
earth's crust were being deposited and while
the various forms of life imprisoned there as
fossils were being evolved from primitive organ
kms. Sir William Thomson cut down these fig
uies 10 something less than twenty million
years. The basis Of his calculation was the rate
et which q piece Of stone will conduct and
radiate heat.
Assuming that the earth had been condensed
T. m a nebulous mass 10 sphere Of molten
matter and adopting 1000 degrees Fahrenheit
gs the temperature at which this material would
begin TO pass from a fluid to a solid state, he set
out TO ascertain how much time would be re-
quired for the crust Of the earth to cool down to
It's present condition. incidentally he brought
forward one or Two Other arguments Inc Sh'S'
was that even If the earth had been suffl-
ciently solid to sustain life more than twenty
million years ago the sun at that time would
not have afforded enough warmth and light to
make existence possible. But he laid the most
stress on the heat conductivity of rock.
In the latter discussion of the matter he ex-
tends the time trifle. Taking note OF Clarence
X ngs estimates and Of some recent investiga-
tons Of thermal conductivity by Carl Barus'
Lord Kelvin admits the possibility OF lapse OF
ttrty million years since the earth's shell first
t,ean to solidify, although twenty-four million
years suits him rather better than the larger es-
innate.
Professor Chamberlain devotes himself entire
~ to showing that the problem is more difficult
han has been supposed He offers no computa-
i'm Of his own as a substitute for Lord kelvin's
and leaves the main question still open In a
thoroughly courteous manner he affirms that
Two or three Of the Glasgow physicists assump-
tons are far from being established.
Lord Kelvin assumed that the earth was once
e. white hot globe. That is his starting point
Professor Chamberlain declares that this notion
e,.s not rest on any conclusive evidence. 1t rs
based he says. on the internal temperature o.
IN globe and the nebular hypothesis. 1t is sug
e.,,rd however. that the former may be ex-
rla,ned by a theory of meteoric aggregation
ca-o ceologist is careful not TO deny the %: 81
tI-y that there was once molten globe. he
merely insists that 1t has never been demon
gt~ated that one existed. Even Lord Kelvin con-
cedes the probability that the material OF "hch
the earth is composed came from meteortes'
t-- ha assumes that when they fell together
thy developed heat sufficient to melt the hard
e.r stone and metal Professor Chamberlain
thinks that the numerous complexities and r-
rec1llarites in the materials OF which the crust
&c made suggest a slow accretion Of meteorltes
rather than one rapid enough to produce
molten globe
II is conceded by Professor Chamberlain tha'
~. energy Of impact may have been sufficient
IL fuse the meteorites when they came together.
But everything depends on the rate at which
tr-v assembled Heat is a result Of gravitaton
srt Interrupted movement If the meteorites-
L.. 4 stone and metal that were chilled TO the
slraUDgly low temperature Of lntersteIai
sl.e-.did not come together in sufficient mum
ters and with an adequate speed, Of course the
h.at developed would be lower than that needeo
Il produce a white hot or molten mass.
Professor Chamberlains contention is that no
OF. has ever worked out this part OF the prop
lem IN such a way as to show either the rate ol
"a OF the consequent temperature IT. for IN
stance the earth was made up Of material which
vas once arranged in ring Ike that around
ssturn-now known to be composed Of small
Uzrticles Of solid matter-this question would De
entirely legitimate When the ring formation
c,tsed n exist and the component meteortes
came together into a ball, did the thing happen
suddenly or gradually? The train OF comet -
made up Of this kind of matter, and the count
less millions Of meteorites there sho" oisposi.