be drawn down by the suction of the
foundering ship, but in my opinion no lifeboat which is well manned is
in danger of this whirlpool. Even old sailors, deluded by this
superstition, have rowed away in haste from a sinking ship, when they
might have stood by and saved many lives.

The question is now often being put, whether it will be possible to
raise the vessels that have been sunk during the war. The raising of a
ship depends above all upon whether the depth at which it lies is so
great that it precludes the work of a diver.

I have already stated that the water pressure augments at the rate of
one atmosphere (one kilogram to the square centimeter) to ten meters'
increase of depth. If a diver working at ten meters' depth is under a
pressure of one atmosphere, at fifty meters he will be under the
tremendous pressure of five atmospheres. This is the greatest depth to
which a diver can attain, and if by chance a diver has gone a few
meters beyond fifty meters, no man to my knowledge has attained sixty
meters. The work of divers at a depth of forty or fifty meters is even
then not very effective, as they are unable to perform heavy tasks,
nor can they remain more than half an hour at a time under such a
pressure, and I am speaking now only of experts; therefore only light
and easy work can be performed by most divers at a great depth and the
appliance of ponderous chains for lifting purposes can only be
accomplished under unusually favorable conditions. To raise any ship
at a depth above thirty meters must be considered as a very efficient
job, whereas if this is attempted at a depth below thirty meters it
can be done only by salvage companies where neither unfavorable bottom
obstacles nor currents intervene. A strong current renders a diver's
work impossible, for it carries him off his feet.

On the high seas the currents change with the ebb and flood. At the
precise moment of the turn of the tide the undercurrent is supposed to
be nil, and the diver must take advantage of this moment to perform
his task. Another difficulty arises from the sand being shifted by the
currents, and settling on the prominent parts of a wreck; it often
envelops them to such a degree that the ship becomes so deeply
embedded in the sand that it is no longer salvable.

According to my estimation eighty per cent of our enemy's sunken ships
lie from fifty to a hundred meters below the surface of the sea, so
that all possibility of their bei