IMPROVEMENTS IN FLOATING DOCKS
Year: 1857

page_text: LETTERS PATENT to George Josiah Mackelcan, of No. 4, Falcon Street,
Falcon Square, London, Engineer, for the Invention of "IMPROVEMENTS
IN FLOATING DOCKS."
Sealed the 2nd March 1858, and dated the 8th September 1857.
PROVISIONAL SPECIFICATION left by the said George Josiah Mackelcan
at the Office of the Commissioners of Patents, with his Petition, on
the 8th September 1857.
I, GEORGE JOSIAH MACKELCAN, of No. 4, Falcon Street, Falcon Square,
London, Engineer, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN FLOATING DOCKS," to be as follows:-
I so construct a floating dock or ship-lift, that it may be sunk to the
bottom of the water, or to any depth necessary to receive a ship, & may
then be caused to float or rise, until the ship is lifted out of the water.
For this purpose I construct a pontoon or vessel of iron framing, sheeted
over entirely with plate iron, so as to form an air-tight & water-tight
chamber; this chamber is subdivided laterally into compartments or separate
chambers, air & water-tight, or it may consist of separate pontoons, united
together by a common deck or platform, as in the Liverpool landing stages;
these chambers or pontoons, or any of them, being filled or partially filled with
water or air at pleasure, will cause the dock to sink or float, with any required
degree of buoyancy; these chambers or any of them are filled with water by

page_text: suitable valves, & emptied by pumping out the water, or by displacing the
water through the forcible introduction of air. Upon the deck of this vessel
I erect a row of tubes or hollow columns along each side, open to the chambers
beneath, of a greater height than the draught of the ship to be docked, so
that they are never entirely submerged; the upper ends of these tubes or
columns carry a platform or path, along each side of the dock & of its whole
length; these platforms are a guide for getting a ship into position, when the
pontoon is submerged, & also sustain temporary shores, until the deck or
platform on which the ship rests, is above water; through these tubes or
columns the chambers are filled with air & emptied of water. The platforms
or paths above referred to, may be constructed of timber, or may be hollow
chests or cylinders of iron, & made to serve as floats to the dock, or to hold
compressed air, which may be admitted at pleasure through the columns to
the chambers of the pontoon, thus to empty them of water by expulsion; these
stages or paths will also affoard the means of attaching awnings, stretched from
the bulwarks of the ship, to protect the workman from rain & sun in tropical
seas, or where desirable. In a tideway the dock may be grounded, & the
ship placed in position & shored; & when left by the receding tide, the water
may be let out of the chambers by valves or scuttles; the dock will then, on
the return of the tide, float with its burthen.
This dock or lift may be constructed without the upright tubes or floats,
in which case some of the chambers will remain permanently filled with air,
as a counterpoise to the specific gravity of the dock, & the others be emptied
of water, & filled with air by flexible tubes.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed by.
the said George Josiah Mackelcan in the Great Seal Patent Office, on
the 8th March 1858.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
JOSIAH, MACKELCAN, of No. 4, Falcon, Street, Falcon Square, London, Engineer,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent bearing date the Eighth day of September, in the year of our Lord
One thousand eight hundred and fifty-seven, in the twenty-first year of Her
reign, did, for Herself, Her heirs, and successors, give and grant unto me,
the said George Josiah Mackelcan, Her special licence, that I, the said
George Josiah Mackelcan, my executors, administrators, and assigns, or such
.

page_text: others as I, the said George Josiah Mackelcan, my executors, administrators,
and assigns should at any time agree with, and no others, from time to time,
and at all times thereafter during the term therein expressed, should and
lawfully might make, use, exercise and vend, within the United Kingdom
of Great Britain and Ireland, the Channel Islands and Isle of Man, an
Invention for "IMPROVEMENTS IN FLOATING DOCKS," upon the condition (amongst
others) that I, the said George Josiah Mackelcan, my executors, or adminis-
trators, by an instrument in writing, under my or their, or one of their
hands and seals, should particularly describe and ascertain the nature of
the said Invention, and in what manner the same was to be performed, and
cause the same to be filed in the Great Seal Patent Office, within six calendar
months next, and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said George Josiah Mackelcan, do hereby
declare the nature of my said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement, that is to say :-
Having in á Provisional Specification described the nature of my Invention,
I will now proceed "particularly" to describe the same, referring for that
purpose to the accompanying Diagrams.
The principle embodied in my Invention, is that of buoyancy, not the buoy-
ancy of a basin or open vessel, which exists only so long as it remains partially
above water, and arises under such circumstances, from its capacity being
greater than its displacement; but that of an air-tight and water-tight chamber,
which may be entirely submerged by pressure, and yet perfectly retain its
buoyancy; or may be caused to sink. by being filled, when on being again
emptied, it will recover its normal condition, as stated in my Provisional
Specification, "being filled or partially filled with water or air at pleasure, will
sink or float with any required degree of buoyancy," the power of flotation
being wholly dependent upon the substitution of air for water within it;
as, for instance, if a given quantity of water be removed from a submerged
chamber or pontoon, it will lift and sustain an equivalent superincumbent
weight; therefore, many chambers or pontoons arranged together as in my
Invention, will exert a power of lift, in proportion to their aggregate
capacity. I thus remove the ship from the water by buoyancy, and -not
the water from the ship as usual in graving docks. The following descrip-
tion will refer to my dock so arranged, that it can readily be put together or
taken to pieces while afloat for repairs or otherwise. Each pontoon can be
detached from its columns and the uniting girders and removed, and again
secured in its proper position at pleasure; in like manner, all its parts can be

page_text: separated and subdivided, to fit them for exportation, and may be reunited, to
constitute the dock or lift in any port or harbour where required.
Plate 1. All the Diagrams on this plate, refer to the dock or lift, as
adapted for use in an open sea, harbour, or river, in which the common atmo-
spheric, or any other pump is used, for the purpose of discharging the water.
I will now refer to the various parts, as lettered for that purpose. a, pontoons ;
b, hollow columns; c, abutments to the columns; d, steps for shoring against,
as they and the ship rise simultaneously out of the water ;. e, girders, which
stretch from end to end of the dock, and unite the pontoons; f, blocks on
which the keel of the ship rests; g, planking; h, partitions across each pon-
toon; i, shores; j, upright feed pipes, one of which descends through each of the
columns, to near the bottom of the pontoons, and are united to the main con-
ducting pipe, which passes over the columns, and supplies the pumps k; Figs.
2 and 4, main conductors; l, m, engine and pumps; h, paths or gangways
along each side of the dock o; Figs. 2 and 4, light caissons, air and water-
tight, which I sometimes use between the columns, as floats or air-vessels ;
when thrown open, as in Fig. 4, there is access to the ship between the
columus; p, valves to admit water to the pontoons, when the dock is to be
more or less submerged, which are under the control of the workmen upon
the gangways.
Fig. 1, Plate 2, represents the dock with the pontoons sufficiently submerged
to receive a ship over them in a tideless sea; a syphon in this case may be
employed, to empty the pontoons as shewn, with the same arrangements of
upright feeders and horizontal conductor to the main descending outlet, com-
municating with a subterranean receptacle, from which the water may be
pumped out at pleasure, by a fixed steam-engine or other suitable power; Fig.
2, Plate 2, represents the lift, in an ordinary enclosed basin, in a tidal sea or
river, in which a syphon may also be used as shown, and the water discharged
by a drain into the tideway at low water, or as the tide recedes. By the use
of a syphon, as described in the last case, there is a great economy both of
time and labour, for when once the syphon is exhausted of air, it may remain
full of water, and an enormous atmospheric pressure is always available, and
may be brought into action at pleasure, to expel the water from the chambers.
By this arrangement ships may be raised in succession for years, without any
appreciable expence in labour.
When many ships are to be brought under repair at the same time, a
cradle on wheels or rollers may be sunk on the lift, and when raised to the
level of a prepared slip or wharf, each ship may be rolled off the lift on to the
slip or wharf.

page_text: When this lift is used to raise sunken ships, it may be constructed as in the
last clause of my Provisional Specification, viz.: "this dock or lift may be
constructed without the upright tubes or floats, in which case, some of the
chambers will remain permanently filled with air, as a counterpoise to the
specific gravity of the dock, and the others be emptied of water, and filled with
air by flexible tubes.
Having now set forth the nature of my Invention, and in what manner the
same is to be performed, I wish it to be distinctly understood, that I do not
confine myself to the precise forms and arrangements of the parts shown and
described, as the same may be varied without departing from the essential
principle embodied in my Invention as above described, and I do not claim the
pontoons or cellular vessels separately; but what I do claim is, the arrange-
ment and combination of all the parts of my floating dock or buoyant ship-
lift, as represented and described, to constitute the same.
In witness whereof, I, the said George Josiah Mackelcan have hereunto
set my hand and seal, this Eighth day of March, in the year of our
Lord, One thousand eight hundred and fifty-eight.
GEORGE JOSIAH MACKELCAN. (L.S.)