IMPROVEMENTS IN RAISING SUNKEN SHIPS AND OTHER SUBMERGED BODIES OR STRUCTURES, AND IN THE MEANS EMPLOYED THEREFOR'
Year: 1880

page_text: PROVISIONAL SPECIFICATION left by Alexander Davidson at the Office of
the Commissioners of Patents on the 14th February 1880.
ALEXANDER DAVIDSON, of Glasgow, in the County of Lanark, North Britain.
"IMPROVEMENTS IN RAISING SUNKEN SHIPS AND OTHER SUBMERGED BODIES OR
STRUCTURES, AND IN THE MEANS EMPLOYED THEREFOR'
The said Invention relates to improvements in raising sunken ships and other
submerged bodies or structures, and in the means employed therefor, and consists as
follows:-
Inside tanks or pontoons of any size and shape, and sufficient strength, enough
water is allowed to flow to enable the tanks or pontoons to be easily sunk to the
ship or other body to be raised. Before these tanks or pontoons are sunk, air is
compressed into the unfilled space in each by a cock situated in its upper part, to a
sufficient extent to fill the tank or pontoon with air at the depth at which it is
intended to operate. A cock is situated at the lowest part of each tank or pontoon,
which when opened, after it is fixed to the ship or other body intended to be raised
(care being taken to fix it so that the cock shall always remain the lowest point, or
on a level with the lowest point), allows all the water to be forced out by the
compressed air, and each tank or pontoon to exert its lifting power. If it be
desirable to use the tanks or pontoons of large sizes, they may be divided into
compartments having free communications between the compartments at top and
bottom of each bulkhead.
When it would be advisable to use instead of tanks or pontoons, or along with
them, air bags or flexible pontoons, this may be accomplished by having hollow
spheres or cylinders of great strength filled with compressed air, and suspended
under suitable air-bags, which would have a large opening to admit of the air from
each sphere or cylinder rising up into each air-bag when released, and which would
also allow the escape of all superfluous air as the pressure diminished, on the bags
rising from a depth to the surface. Each sphere or cylinder will be suspended in
such manner under each air-bag to be filled as will enable a cock fixed on its
upper part, having a short pipe leading up to a short distance above the level of the
lowest extremity of the air-bag, to deliver its contents into the air-bag. The lowest
extremity of the air-bag should be a sufficiently strong ring of metal, to which a
network of rope over the air-bag should also be attached, having continuations for
attachment to the vessel or body to be lifted. If it be not convenient to take down

page_text: in one hollow sphere or cylinder enough air to fill an air bag, the sphere or cylinder
could be brought to the surface, refilled, sunk, and placed in position under the air-
bag by a diver.
The air-bags are of very thin and flexible texture, thoroughly air and water
proof, having each two or more flexible tubes of suitable length of the same material,
or it may be of a heavier and stronger material than the air-bags attached to and
opening into them, the other extremity of the tube terminating in a metal coupling
having a screw or other arrangement for attaching it to a corresponding coupling.
The coupling at the end of each tube will require to be of such weight as to keep
the tube when fully inflated with air in the water, with the coupling at its lowest
extremity. Hollow spheres or cylinders of sufficient strength and of such weight
that they will sink in water, and having couplings to enable them to be attached
to the tubes of the air-bags will be filled with compressed air sufficient to fill cach
air-bag at the depth at which it is intended to operate. Should it be inconvenient
to take down in one cylinder or sphere sufficient air to fill an air-bag, several spheres
or cylinders could be used, care being taken to leave one or more tubes open to
allow the superabundant air to escape as the pressure is reduced, on the bag rising
from a depth to the surface. The air-bags would be taken down to the ship by
divers, and passed through any suitable openings in the ship, such as cabin windows
and port-holes, the divers taking care to pass the bag through the opening into the
ship first, and the magazine of compressed air last, and just as he passed it from his
hand would liberate the air by turning a cock or touching a suitable spring.
Where it is not convenient to take down in one sphere or cylinder sufficient air to
fill an air-bag, another arrangement would be to have several spheres or cylinders
coupled on to each other with couplings similar to those joining the tubes of the
air-bags and the first sphere or cylinder. They could be coupled before leaving the
surface, or might be let down or taken down singly to the divers, who could couple
them, turn cocks, and connect them all, and last of all turn the cock or touch the
spring that would liberate all the air into the air-bag.
The pontoons could either be charged with air by a flexible tube from a receiver
or magizine on board a vessel, alongside of which they would float, or cylinders
could be charged from the magazine, and the pontoons charged from the cylinders
through suitable couplings.