Evening star., 1954-01-06
Alaska Observatory
Is Reached by Plone
Is Highest in Hemisphere;
Suns TiduI Pull Explained
By Thomos R. Henry

by IhomoS K. Heny
North Americas highest observatory,
designed primarily for study Of cosmic
rays, now is in operation on the per-
petually ice-covered 14,006-foot summit
Of Alaskas Mount Wrangell.
Observers get to the mountaintop by
airplane-something unique in the his
tory Of mountain climbing.
The daily summer temperature
ranges from to Is Fahrenheit, but the
men 60 about in light summer clothing
because Of the intensity of the sun
shine.
Primary purpose Of this observatory
in the sub-Arctic skies is to study cos
mic radiation. It is not far below the
region where collision Of the primary
cosmic particles, entering the earth's
atmosphere from outer space at ener-
gies Of billions Of volts, collide with
atmospheric particles to create the still
mysterious meSons-parts of the bind
ing energies of atoms which exist as
particles of matter for infiniteSimally
brief periods. These now are one of
the major studies Of interest to physi-
cists. "
Educator Lands on Top.
The Mount Wrangell observatory is a
joint project Of New York University
and the University Of Alaska, estab-
lished with the cooperation of the Of
flee Of Naval Research and the Quar-
termaster'S Office of the Air Force. A
major problem was that of making
airplane landings on q mountaintop.
The possibility of doing this was es-
tablished by DIR. Terris Moore. presi-
dent of the University of Alaska, who
made the first landing after a party
had climbed the mountain on foot. It
has been found that landings can be
made in summer about five days each
week.
There are predominantly solar tides.
The great oceans are divided into
tidal basins in each of which the
tidal movement responds in its own
way to the gravitational pull Of the
moon.
These cause major complications in
tide prediction. according to Rear Ad-
miral Leo Otis Colbert, former chief
of the Coast and Geodetic Survey. in
report issued by the Smithsonian In
stitution.
Predicting tides would be quite
simple, Admiral Colbert says, if the
whole earth had a smooth surface COW
cred by uniform depth of water. Then
the height of the tide anywhere could
be predicted fairly well from the posi-
ton of the moon at any time. A great
deal, however, depends on the contours
of sea bottoms and surrounding lands.
Basins in Atlantic.
For tidal behavior, Admiral Colbert
says, the Atlantic Ocean can be con-
sidered as consisting of two basins.
The larger Of these extends across the
North and South Atlantic with the
eastern coast of North America at one
end and the Antarctic Ocean at the
other. Within this basin the moon
caused oscillation of the water is such
that high tide along the North Ameri-
can coast occurs almost precisely IL
hours after the moon crosses the
meridian Of Greenwich and low tide
comes approximately six hours later
The other, smaller basin is bounded
by the north Brazilian coast and the
North Atlantic shores of Europe. Here
the oscillation due to the moon brings
high water on the coasts of Iceland
and Greenland on one end and the
coast of South America on the other
eight hours after the moons transit
of Greenwich.
The Indian Ocean is divided into
three such tidal basins and the Pacific
into two.
Tides are somewhat complicated
everywhere by the gravitational pull
Of the sun, but in most places this is
very small compared with that of the
moon, owing to the fact that the
magnitude of these pulls varies with
the mass Of each body. but inversely
with the cube Of the distance apart,
or the cube Of 90 million miles to the
sun compared inversely with 250,O00
miles to the moon.
There are few places, however,
where the arrangement of land and
water is such that the predominant
tide-producing force is solar This Is
the case with tides on the shores of
Tahiti. High tide comes each day at
noon and at midnight and low water
at am. and 6 pm, regardless Of
the moons position. The Tahitian
tides are quite small. A much larger
predominantly solar tide recently has
been found, Admiral Colbert says. on
Tuesday Island a small island in the
Torres Strait of the northern coast
of Australia.