The Savannah morning news., 1900-07-07
rpE AGE OF THE EARTH.
,y CHEMISTS GO TO WORK TO
nv COMPUTE II.

ala, that scientists for years have
ICING TO answer. Some have an
IL accordng to their own assump-
.,1 calculations, and their results
.roNn discrepancies ranging from
,.,,s IN tens of thousands of millions
,.., q *. Gilbert of the United States
...,,oieai survey, who discussed the sub
,t. conference of scientists al Co
,., 1-7ivcrsity during the past week,
~ ro, answer the question.
ornat vain expectation may not be
.d % he said. II admit at the outset
-, nave not solved the problem ard
..n submit you no estimate"
u.h., he did do, however. was TO show
.,u scientists arc approaching and must
~ future approach the problem, what
~ the means by which they can nope
W. time 10 answer the question of the
| sge Of The earth'
a., attempting TO measure the age of the
,t scientists make use of either con-
.n,,o,e processes or rythms, just as we
" o,1iiparilv in measuring time
1ta clensydra. a more modern form of
,t.t ia. the hour-glass with sand substi-
WA FOR water, and the taper. which is
NV, GOD in uonastic vigilS in the form
81 Tho Graduated candle, are examples of
| .t.,nnlication of continuous processes to
| .,s.slrine time. The pendulum, on the
| AMOR hand. is an example of the use of
| ',,,bm i'm time measurements.
rhue The motion of the earth IS con-
..nnons as compared with any other ce-
| ,.e.,sl hodv il is rhythmic. Compared
/ u.;,b fxed star, 1t gives us the siderial
d.v with the sun, the solar day, nearly
| sa,r minutes longer. with the moon, tie
/ ,ncar dav. longer still by forty-nne min
/ ,ss The siderial day is reckoned only
/ \, astronomers. The lunar day finds eX-
4 .r,,.i7n in the tides. Besides the day, there
| ~, Two other natural time limits, the
| r,onth or rhythmic period of the moon
rsqsrdel as a luminary, and the year or
| rtythm Of the earths orbit. The genera
,or and the dynasty are two time meas
mrs of waning importance.
I'm computing geologic time. scientists
make use of a variety of continuous proc
esses
First may be mentioned river deposits.
rbroughout the ages the rivers have been
deoositine layers of sediment at their
uonbs In course of time these deposits
have been converted into rock, and in
eliminating the time necessary to produce
The various layers biologists have to take
account of their volume and thickness.
The amount of the deposits equals the
amount of material washed away, and by
calculating the amount of material car
rIed away By rivers in given period Of
tme. biologists can estimate the amount
NJ time represented by the different lay
A1,s.-
hom the accumulat ton of sand in beaches,
ANDREWS estimated the age of Lake Mich
[igan.
Another system of measuring geologic
Mime Is founded on the principle of the
evolution OF life Fossils are the records
In this case. and account is taken of the
amount OF change from one full record to
the next
/ The study of the processes pertaining
| Ia the earth as a planet opens up other
ways Of approaching the problem of geolo-
ec time
4 As the rotation of the earth causes
: the tides" Prof Gilbert says, land as
! the tides expend energy the tides must
pct as brake and check the speed of
Rotation. Therefore the earth has in the
past spun faster than now, and ITS rate
of spinning at any remote point may be
computed Assuming that the whole
globe Is solid and rigid, and that geologic
record could not begin until that condition
had been attained. there could not have
been great checking of rotation since
Fonsolidaton. For If there had been It
roud have resulted in the gathering of
he oceans about the poles, and the barring
the land near the equator, condi-
On very different from what actually OBJ
aims This line of reasoning yields an
OBSCURE outer limit to the age of the
tarth
On the assumption that the globe lacks
omelhing of perfect rightly, G. II. Oar
Nin has traced hack the history of the
tafth and the moon to an epoch when
ne two bodies were united, their separa
Ion having been followed by the gradual
nargement of the moons orbit and the
gradual retardation of the earth's rota-
on and this line of inquiry has also
eded an obscure outer limit to the an
quiy Of the earth as a habitable globe.
Vhe OF the most ella borate of all COM
uauons starts with the assumption that
he initial epoch, when the outer part
me earth was consolidated from
qua condition, the whole body of the
lahet had approximately the same tenn
"dfl cooled by outward radiation. there
vas now of heat to the surface by con-
ucuon from below. The rate of this flow
as diminished from that epoch to the
present time according to q definite law
lu the present rate, being known by OBJ
'duoh, affords a measure of the age
'ne crust The strength of this compu-
Von lies In its deflniteness and simplic-
us weakness in the fact that il pos
'aeS knowledge of certain properties
LUX when subjected TO temperatures
seator than have ever been investi-
a~l eXperimentally.
Gunner calculation is based on the as
upuoh that loss of heat from the sun
10'ompanied with loss of volume The
49, vi ms basis. is shrinking at a def
iale A computation based on this
mas told how many years ago the
uIaneter was equal to the present
sue'ef Of the earth's orbit. This sets
'oI init to the extent of geologic
,a .IIAIhg to rhythms as a means of COM
lug geologic time. we find that the
ma mas snow many traces of them.
."e udal rhythm may be appealed to
al explanation of certain features of
s'"entalion. The thin layers found in
s "e Iocks may have been flmy deposits
ny the tides on the other hand,
mar layers may indicate the term of
49, They may have been deposited by
Ns Which had, like the Nile. but one
sTTeoe food each year.
4e number of rythms IN the solar uni
is very large. but only two besides
TWO mentioned have been able TO write
s. .lse'Ves IN a lesible way la geologic
These are the rhythms of preces-
W. ahu eccentricity. Since the sun is
~ the center of the earth's orbit, that
the northern and southern hem
e"''es do not receive heat in the same
~ The prr 1, fg