Evening star., 1927-05-22


$4,000, ,ooo. 900, 900, 100000 tons.
These staggering figures are
Il announced-with the sun.
moon and stars included for
full measure. The ponderous task of,
figuratively, putting this planet into
tho balances has just been completed
by DR.. Paul r. Heyl of the Bureau OF
Standards, ending three years of in
termittent effort in a cave below the
surface of the ground.
This rechecking of the weight Of the
weight of the earth has served to in.
dicate that it's mass is less than has
been commonly supposed by approXi.
mate1y 1 part in 1900. Persons flip
PANTY inclined will contend. in the
light of this new scientific fact. that
Mother Earth Is a vegetarian and has
been on a reducing diet. Meat eaters,
somewhat alarmed, will insist on more
pork and beef on the menu. lest this
planet suffer a subtraction from its
gigantic proportions.
tt /. spectacular undertaking OF
weighing the earth. which was previ-
ously attempted 80 years ago, In.
volved the use of equipment more APP
r aling to the popular imagination
than the mere figures indicating the
gravitational constant. Thirty-five
feet underground in the sub.basement
of the Electrical Building Of the Bu-
reau of Standards, during internlit-
tent periods of the last three years,
DR.. Heyl could be found.
He Is not recluse--far from it. His
occasiL al retreats to the depths oil
this cave were in pursuance OF tests
in rechecking the weight of the earth.
Here. where the frost of Winter and
the heat Of Summer did not penetrate,
were installed sensitive instruments.
II want to find out how much heav.
ier the earth Is than that cylinder.
DIR. Hey! would suggest to visitors, in
reducing this gigantic undertaking to
simple terms. The apparatus was not
formidable In appearance-in fact, II
was simple and even insignificant look
ir~ compared to the immensely of the
project. There were two gold balls.
whose weights were accurate to one
part In 100000. suspended from the
end of an aluminium bar. The latter.
In turn, was hung by means of light
wire. This permitted the apparatus TO
near these gold balls and their attrac.
ton for moving bodies was measured
by the amount the gold balls deviated
from the true course OF their SWING.
The entire mechanism was operated IN
a vacuum, and the observer measured
it's behavior at a distance through
series of mirrors. The weight Of the
operator. as we'll as his body warmth,
woulr have affected the true operation
of the apparatus, had it not been re.
motely controlled.
The gold balls OF this earth'weigh'
| ing apparatus were started swinging
by holding a bottle of mercury near
them. These balls, contrary to BE-
| lief having currency I'm some quarters.
| did not swing in an orbit. They
swung back and forth as II torsion
| pendulum, the period Of the swing
| being about 80 minutes The require
ments for building this apparatus
| were so exacting that the mechanics
! consumed IL months in constructing
it. Thus approximately four years
| were required to complete the task OF
| weighing the earth.
'Of what value is it to the man or
| the street to know precisely the
/ weight of the earth?" this writer in
| quired of DR.. Heyl, who has found the
constant Of gravitation to be 0.0000000.
| 664. compared with the previously ac-
; cepted value of 0.0000000666.
| For practical purposes" he re.
| piled. lit means closer knowledge OF
sravitation. 1t is function Of the
| Bureau Of Standards to determine the
constants with the greatest possible
degree Of accuracy. incidentally,
these results should give US an indica-
| ton Of the earth's density. Although
no one may ever get down to the GEN.
ter OF the earth and dig out the iron