Evening star., 1935-03-07

Most Of mans standards Of measure
ment-temperature. time. length,
height. latitude and all the rest-are
based on fundamental "fictions."
The scientist may measure some
physical reaction in terms Of thou
sandths of seconds or millionths OF
millimeters-but the seconds and mil
limeters themselves are essentially in
ventions of the human mind.
Such is the conclusion of DR.. L. B
Tuckerman of the United States Bu-
reau Of Standards. who himself has
conducted some of the most precise
measurements ever made. Thus. he
points out, the measurement of time
is in terms of mean solar seconds,
based upon the period of the earth's
rotation on its axis. Yet astronomers
compute that this rotation is subject
to irregular variations so that 1t
sometimes is as much as 80 seconds
ahead or 20 seconds behind schedule.
Eventually the solar second may be
abandoned in favor Of "coSmical
second" which will take all these var
iations into account. But still, says
DR.. Tuckerman, it will be q fiction
Even more Of a fiction is that of de-
grees Of temperature on any scale and
even more obvious Is the fiction OF
degrees Of latitude and longitude upon
which maps are based.
1t has been found that the astro-
nomical latitude of a given point on
the earth's surface varies, partly reg
ularly and party irregularly, with
time. Efforts to solve this puzzle,
DR.. Tuckerman explained, led to the
assumption that the axis of the
earth was wobbling. That is, the
North Pole. which is one of the refer
ence points in latitude determina-
tions, would not stay fixed. Hence
latitude lines, as determined by refer
ence to the stars, shift. So it has
been necessary to adopt a fictitious
north pole in an assumed position,
instead of the actual position of the
top of the world at any given time.
This fictitious north pole IS its mean
position between the years 1900 and
1907. The necessity of this fiction,
he pointed out is shown by some
recent check-ups of two stations,
about % miles apart, on Kauai, one
of the Hawaiian Islands. The rela-
tive position of these stations was
determined both by astronomical OBJ
servations and by triangulation. They
should have checked exactly. AS a
matter of fact, there was difference
of about mile and a quarter. But
when the check-up Is made with the
latitude and longitude based on the
fictional pole the difference becomes
very small.
Another striking instance is the
boundary between the United States
and Canada. Back In 1918 1t was
fixed, between the Lake of the Woods
in Minnesota and the Rock Noun
tains, as the 49th parallel of latitude.
It afterward was extended to the
Pacific.
ITO the treaty makers who so de-
fined this boundary" says DR.. Tucker
man, 'this probably seemed very
definite. However, in memorandum
prepared in 1901 we read that 1t Is
possible that no point of the line thus
traced as the astronomic parallel may
lie on the particular parallel sought,
and it was not until 1925 that
geodeSists of the International Bound
ary Commission were satisfied that
the 49th parallel of latitude was ade-
quately hemmed in by geodetic and
legal fictions.
I'VE all know what the 49th par
allel of north latitude should look
like-a smooth, gently curving line
just 20 degrees north Of the Equator.
such . line can be only . schoolboy's
dream q Q geodesigt's dctioa. At ons