Evening star., 1925-03-14
BACKGROUND OF EVENTS
BY PAUL Y. COLLINS.

The earth is exactly 7.926.S78 miles
in diameter at the Equator and
7.S99.694 miles through the North and
South Poles The measure, as an
nounced by DR.. John F. Hayford, late
head of the College Of Engineering,
Northwestern University, Chicago, is
so exact that the fraction, carried
out to 67S-thousandths of a mile,
shows that the last feet is precisely
calculated, for thousandth of a mile
is SIS feet. Every schoolboy knows
that the earth is fattened at the
poles. Now we know that it is ex-
actly 26sS4 miles less in diameter
through the poles than through the
Equator.
OF what practical value is the ex-
actness of the measure of the diam
eter of the earth? All science is even
tually of practical value, however alb
struse it may seem upon discovery.
x x * <
The United States Coast and Geo
detic Survey has made exact surveys
along both the Atlantic and Pacific
coasts, along the Rocky and Alle-
Eheny ranges and through the Middle
West; also three transcontinental
lines of latitude. Along all these
basic structural lines official, num-
bered bronze bench marks are plant
ed. and at the headquarters in Wash
ington a record is kept of the exact
geodetic location of these marks, so
that engineers may tie up their local
surveys to known points.
Local surveys ignore the earth's
curvature, because the distances are
too short for the arc to be calculated,
but transcontinental lines for rail-
ways or State boundaries must cal
culate the arc of the rotundity of the
earth and to do so 1t is necessary to
know the exact size of the mundane
ball-the "spheroid."
The most precise measurement Of
the earth is that made by the late
DR.. Hayford He had taken years in
making and correcting astronomical
observations and making computa-
tions by triangulation, beginning
some 90 years ago when he was
connected with the United States
Coast and Geodetic Survey. Last
week his. measures received the ep-
proval Of the International Geodetic
and Physical Union. Hereafter the
Hayford measures will be the basis
of all engineering and surveying
standard for fixing international
boundaries and bounding real estate.
Heretofore, each country has had
it's own basic point and its own
spheroid by which it made its sur
yeys. and there was serious over
Tapping of international boundaries.
Nations have gone to war over such
boundary disputes. Men have squan-
dered millions in law suits over
faulty surveys, due to variations in
basic points. In New York City,
where land is counted by the half
inch, there are half dozen old basic
bench marks" making great con-
fusion in surveying. When settlers
rushed out into the untracked West
and took up homesteads, the surveys
were based upon astronomical obser-
vations and often overlapped; liti-
CATION, to this day, is the result.
X 4 X X
A survey may be based upon as
Economical observation or upon
triangulation, the latter starting
from fixed landmark But the
two methods do not always agree In
results. though both are made with
the utmost exactness.
According to the expert geodocist
of the United States Coast and Geo
detic Survey, DIR. Bowie, it was a
great puzzle to scientists to harmon
lie the discrepancies of astronomical
observations with triangulation sur
veys until the science of isostasy ex-
planned the complications Of the