Evening star., 1953-08-17
Bays Have Two Layers,
Flowing Different Ways
Chesapeake Tests Disclose
Some important Facts
By Thomos R. Henry
avs are double-layered.

Bays are double-layered.
OnEhe top, water flows downhill into
the sea. On the bottom it flows down.
hill into the land.
The two flows are almost exactly
equal. except for the fresh water con-
Stantly being brought in by rivers.
This has been demonstrated conclu-
sively for Chesapeake Bay, at the Ches-
apeake Bay Institute of Johns Hopkins
University, near Annapolis. 1t pre-
Sumably Is equally true for all river
fed estuarieS Of the seas. The double
flow is an important factor in biology
and in the worlds food supply. It is
by this reverse flow, for example, that
oysters and crabs continue to exist in
shallow waters.
Bottom Has Far Less Oxygen.
Approximately the bottom half of a
bays waters, according to DR.. Donald
w. Pritchard, director of the Institute,
is considerably saltier than the river
fed top half. It is ocean water which
flows in to replace that carried out to
sea by the pull of the river currents.
The bottom water is slightly heavier
than the top water. It also contains
far less oxygen-a matter of consider.
able concern sometimes.
Movements of bay water become
quite complex when investigated. First
are the diurnal movements of the tides.
They are approximately equal and OPP
posite. 1t is only when they can be
averaged out mathematically that the
true water movements can be deter
mined.
The situation is complicated by the
rotation of the earth. This tends to
throw the water in the upper layer
towards the east bank of the bay, with
the result that the surface of the bot
tom, saltier layer is tilted downwards
towards the east. The greater the tilt,
the less the oxygen. One result of
this is high mortality for the fish and
crabs that normally live in this layer.
They are literally drowned.
The bottom of most of Chesapeake
Bay, Institute tests have shown, is q
place of almost complete darkness.
Ordinarily light penetrates about 600
feet into clear sea water Here, owing
to the turbidity of the water, it is
almost completely absorbed in 40 feet.
Suits for Wear in Heat.
In suits that look like those Of Arctic
explorers. Naval Ordnance Laboratory
workers are spending periods of an
hour working hard in rooms at tenn
perature of 160 degrees Fahrenheit
and with humidity up to 20 per cent.
They are demonstrating that clothing
can keep a man cool as we'll as warm.
On few occasions they have been
able to work with the humidity up to
so per cent.
The hot-room suit is a balloon-like
envelope which is put on over the
workers regular clothing and incloses
everything but his hands and feet. The
theory Is to create layer of constantly
changing cool air around the body in
order to maintain safe temperature by
carrying off body heat. Air is drawn
from the regular building compressed
air supply, at temperature of about
10 degrees. An ordinary hose is run
to the suit from an already existing
air outlet.
When the worker enters the chamber
with the suit on. he Immediately con-
meets the hose to the suits air inlet,
located in the right leg.s This causes
the suit to initiate, surrounding the
worker with barrier of cool air and
allowing him to move about freely.
Lucite Covers Face.
The hot-room suit is q one-piece af-
fair made of very close weave nylon
material. The face part is of curved
lucite and the crown part of the head
covering consists of an open-weave
nylon material that permits a more
rapid outlet for the air. Inside the
head covering is band which fits over
the wearer's head. providing support
for the suit.
For most of the conditions under
which the equipment is supposed to be
used it was not thought necessary to
provide cover for the hands and feet.
The suit ends at the wrists and anklets
where 1t is secured with drawstrings to
maintain the light pressure inside.
The suit was made and materials
selected with the idea that air should
leak out at all points through the cloth
and seams. The open-weave nylon in
the head piece purposely lets the air
leak faster, thus providing more rapid
air change where it is needed for
breathing and evaporating moisture
from the face. Air is fed to the suit
at rate just sufficient to cause the
desired leakage and still keep the suit
inflated.