Evening star. [volume] (Washington, D.C.) 1854-1972, 1913-06-15
DIVING DEPTHS

X
seem that there is no limit to the depths
to which a diver or a submarine boat might
go Such, however, is not the case. What
prevents diving to great depths is the enor
mousy increasing pressure OF water. No
diver without suit can go over one hundred
and fifty 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
To remedy this the diving suit was in
vented but there is limit also to its depth
At depth of one mile the pressure due to the
water alone is a hundred and sixty-five tons
to the square foot. Even if diving suit
was devised to withstand this enormous
pressure, trouble would be found in getting
pipe line that long and withstanding the
same pressure, that would not break of its
own weight.
In the case of submarine boat t is slight
" 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 a larger engine is pro-
cured, it itself weighs more, larger quarters
are needed for it, etc. So there is we'll de-
fined limit to a 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 comparatively incompressible, a
cubic foot of it 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 slight
" 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. All this because the pressure on
the square foot considered is simply the col
umn of water above it, and this column is in
cubic feet the same number as its depth in
feet for its cross section is one square foot.
SO this multiplied by the weight of a cubic
foot gets the pressure in pounds on square
foot At depth of five miles the number of
feet being twenty-six thousand four hun
dred, we have that number of cubic feet to
multiply by sixty-two and half. The an
swer is one million six hundred and fifty
thousand pounds, or eight hundred and
twenty-five tons to the square foot pressure
| No known hollow vessel can withstand this
WHILE on the subject of increasing water
" pressure number of interesting obser-
| vations can be made in connection with air
compressibility. Air is very compressible,
| the volume decreasing as the pressure in
creases. If a bottle 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 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 by 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 compress
| iblc 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