Rock Island Argus. (Rock Island, Ill.) 1893-1920, 1913-10-23
WATER PRESSURE
Tremendous Force Exerted at
the Bottom of the Sea.


diving to great depths is the enormous
ly increasing pressure Of water. No
diver without a suit can go over $50 |
feet, because the pressure on the body /
is then about FIVE tons to the square
foot on his body. Eardrums would be |
STAYED in, and other fearful difficulties /
would result.
invented. but there is a limit also to |
Its depth. At depth of one mile the |
pressure due to the water alone is 165 !
tons to the square foot. Even if a div !
ing suit was devised to withstand this |
enormous pressure trouble would be
found in getting pipe line that long
and withstanding the pressure that
would not break of its own weight.
In the case Of a submarine boat it
is slightly different Here only the
strength Of the boat is the necessary
thing. But to be strong the walls have
to be thickened. and this adds to the
weight. consequently adding to the
load to be pulled through the water
and so at last the limit of the engine
propelling the boat is reached If
larger engine is procured it itself
weighs more, larger quarters are need
ed for it. etc. So there is we'll de-
fined limit to marine boats diving.
Let US take the extreme depth of the
sea so far found. that of FIVE miles, and
find the pressure to the square foot on
the bottom. AS water is comparative
~ incompressible. cubic foot of 1t
weighs practically the same on the
surface as at the bottom of the sea-
In the case of fresh water this is sixty
! two and a half pounds. Salt water
weighs slightly more So all one has
| to do to find the pressure due to the
water at any depth is to multiply the
| depth in feet by sixty-two and a half.
| and the answer is apparent at once in
| pounds.
At depth of five miles. the number
| of feet being 26,400 we have that num-
Der of cubic feet TO multiply by sixty
| two and half. The answer is $50
600 pounds. or s25 tons. to the square
foot pressure. No known hollow YES
sci can withstand this
While on the subject of increasing
| water pressure a number of interesting
| observations can be made in connec
ton with air compressibility. Air is
very compressible, the volume decreas-
| ing as the pressure increases. If a bot
tie is tightly corked it will contain air
at ordinary pressure of fifteen pounds
to the square inch. and that is the
pressure it exerts. Then tie a weight
to the bottle and let it down in the sea
by means of string. On bringing it
to the top again it will be found that
the stopper has been forced into the
| bottle lIy the water pressure. If the
| bottle is filled with water and stop
pered and let down no such thing takes
place, showing that water is not COM
pressihle TO any great extent.
If by any means some air could be
placed at the bottom of sea five miles
deep It would not rise to the top, for it
would be denser-that is, would weigh
more to the cubic foot than water
and the water would have to float on
the air; hence no man knows if the
bottom of our seas is wet or not.
There is only one thing that would
prevent the air from becoming this
dense, and that is if it was cold enough
it would liquefy. However. it is al
most impcssible-is. in fact. impossible
for anything at the bottom of the sea
to be colder than 4 degrees c., for if it
got colder the water around it would
become colder and larger and conse-
quentiy lighter and rise, and its place
would be taken by 4 degree water,
which would bring the object to that
temperature. So we have no argument
against the suggestion, for the temper
AZURE at or below which air liQuefies is
between 100 and 200 degrees below
zero G.
Some people seem to think that a
stone thrown into the sea can sink
only to a certain depth and is there
held suspended on account Of the pres
sure of water. A body immersed in
fluid is bnoyed up only by the weight
of the fluid displaced We have found
that water is practically incompress
j ible, so if the stone displaces a cubi.
foot of water that water weighs the
same. or practically so. al the top OF
: at the bottom OF the sea So the stone
would be buoyed up only by that con
3 slant force and would be carried down
= by its weight. Thus the difference in
the forces would be always downward
and the stone would sink to the bot
tom.
: In fact IL the stone is at all com
pressible the tendency is for it to gel
i heavier per unit volume as it goes
down. for we have the same weigh;
; in a smaller space. 1t will be remem
I bered that this is what happens to the
e air if we take 1t In rubber bag under
the surface or the sea. The volume
gets less and less. consequently weigh
ing more and more per unit volume
e and dispIacing less and less water anc
i being buoyed up less and less until al
$ last place is reached where the aiI
d weighs more volume for volume than
does the water and IL will not rise
Lawrence Hodges In Chicago Record
J Herald.