AN OSCILLATING SCREEN BREAKWATER
Year: 1868

page_text: LETTERS PATENT to Robert Saunders, of Croydon, in the County of
Surrey, for the Invention of "AN OSCILLATING SCREEN BREAKWATER."
Sealed the 12th February 1869, and dated the 28th August 1868.
PROVISIONAL SPECIFICATION left by the said Robert Saunders at the
Office of the Commissioners of Patents, with his Petition, on the
28th August 1868.
I, ROBERT SAUNDERS, of Croydon, in the County of Surrey, do hereby
declare the nature of the said Invention for "AN OSCILLATING SCREEN
BREAKWATER," to be as follows:-
My Invention consists of one or more tubes of iron, or a a series of them,
and so moored in position as to form two legs of a triangle with the apex
seaward. In some instances I would form one line of tubes parallel with
the coast; each tube I prefer to moor separate from the other so as to
allow them to ride independently of each other, leaving only a small
space between them.
I would sometimes prefer using wood or other material to form the
floating portion or backbone of my structure instead of metal tubes.

page_text: Having the tubes or backbone of my structure provided I proceed to
describe that which hangs below the surface of the sea which is held or
suspended from the floating body, and which I designate the screens,
which I depend upon chiefly to break the force of the sea; these I
prefer to make of iron or wood in one or several pieces; in some instances
I would place them parallel to each other with spaces between each log
or other submerged material forming the screens, these may be extended
towards the bottom of the sea as far down from the floating tubes or
backbone as I may deem expedient to check or to counteract the surge
or motion of the water. These screens will be suspended from the
backbone of the structure by chains, bars of iron, or otherwise, and
the said tubes may be made to carry one, two, or more tiers of screens,
the object being to mitigate or to nullify the force of high seas, so
as to afford a safe anchorage for ships within its influence, and to
render the landing for boats on a lee shore more practicable and
convenient.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Robert Saunders in the Great Seal Patent Office on
the 23rd February 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
SAUNDERS, of Croydon, in the County of Surrey, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-eighth day of August, in the year
of our Lord One thousand eight hundred and sixty-eight, in the thirty-
second year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Robert Saunders, Her special licence that I,
the said Robert Saunders, my executors, administrators, and assigns, or
such others as I, the said Robert Saunders, 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 "AN OSCILLATING SCREEN BREARWATER,"
upon the condition (amongst others) that I, the said Robert Saunders,
my executors or administrators, by an instrument in writing under my,
"

page_text: 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 Robert Saunders, 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 :-
This Invention has for its object the formation of harbours and the
protection of roadsteads, exposed piers, and landing places, and generally
for breaking the force of a running sea by the use of breakwaters formed
by mooring afloat wrought-iron pontoons with suitable screens attached
suspended from them and reaching to such a depth as may be found
needful.
I base my said Invention on the principle that the agitation of the
sea dangerous to shipping extends only to a very limited depth, and
that a floating structure or series or structures reaching to such depth
may be so formed as effectually to arrest the wave motion of the surface.
I propose to moor a pontoon or series of pontoons to seaward of the
waters to be protected; the pontoons I form by preference of wrought
iron, and they may be of such size and form as the position and circum-
stances in which they are placed may render needful. The office of the
pontoon is to sustain the screen, which by preference I make of wrought
iron or wood, and which reaching to the desired depth breaks the wave
or prevents the wave motion from being transmitted to the waters
beyond.
The shape of the pontoon or screen may be varied, the Invention
being the use of a pontoon sustaining afloat in deep water a screen which
shall descend to such depth below the surface of the water as may be
needful to arrest the dangerous agitation of the water.
I now proceed to describe particular forms of this breakwater which
I claim as important features of my Invention. To a series of pontoons,
which by preference I arrange across the structure and presenting an end
to the sea, I attach a series of longitudinal vertical bulkheads spaced by
preference from three to six feet apart. The bulkhead or screen farthest
seaward I make to descend but a little depth below the surface, and every

page_text: succeeding one will descend a little deeper than the one before till the
bulkhead at the back of the structure reaches the greatest depth. In
the longitudinal vertical spaces between the bulkheads the water has
freedon for vertical motion but cannot make horizontal progress, and
being isolated from the water in the adjoining spaces cannot affect it
either by pressure or in any other way assist in propagating the wave
motion beyond its own space. These screens or bulkheads need not be
strictly vertical or straight, but may at times be curved either above or.
below or inverted as may be found best.
In further explanation of my Invention I annex hereto a Sheet of
Drawings.
Fig. 1 shews a breakwater in section, Figs. 2 and 3 being different
views of the same on half the scale of Fig. 1.
P, P, P, are the wrought-iron pontoons which sustain the screens
afloat. a, a, a, are the screens or bulkheads, in this instance shown of
wrought iron, having spaces between open above and below, and in which
the water has free vertical play; b, b, is a timber chafing piece to prevent
shipping or other bodies floating on the surface injuring the pontoons or
screens; d is a Saunders' Patent safety spring, which I consider it
desirable to use on the moorings to save any sudden strain or jerk;
e, e, c, e, are powerful moorings laid so as to hold the structure with
broadside to seaward, and so attached to it as to distribute the strain
as much as possible; c, c, are lighter mooring chains.to the land side.
Figs. 4, 5, 6, 7, 9, 10, 11, 12, 13, shew some of the various forms
which in section this particular description of breakwater may take.
In this form of my Invention I lay particular claim to three principles
involved.
First. The isolating the water in vertical water spaces and thus dividing
the wave into a number of detached volumes.
Second. Gradually increasing the depth of the bulkheads beneath the
surface from the seaward face to the rear, so that the force of a breaking
sea is received in detail on the structure.
Third. Having a broad vertical face to the land side which offers the
greatest resistance to the structure being forced through the water by
the force of the wind or blow of the sea. In shallow water and when
other local circumstances present objection to the floating structure as
before described, I would prefer the screens fixed to the bottom by

page_text: suitable legs instead of suspending them afloat placing them sometimes
so as to have some space between the lower edge of the screens and the
sea bottom.
Fig. 8 on the Sheet of Drawings represents another form of pontoon
breakwater presenting the form of a wedge with a thin edge to seaward
and the broad base to the land side, whereby the running sea on the
surface is split and broken and flung upwards from the upper face, and
the water rising with the wave motion from below and coming in contact
with the lower surface of the wedge is forced forward as it rises. The
broad base at the back gives great resistance to the structure being forced
backward by the force of the sea or wind, whereby the strain on the
moorings is materially eased; such portion of the upper part as is needful
to float the whole in the desired position is formed of a wrought-iron
pontoon or pontoons.
In mooring a number of these to form a continuous breakwater I
adopt one or more lines, but I prefer a double line in which the pontoons
of the inner line are placed opposite to the openings left between the
pontoons in the outer line. In some instances I prefer to make the
screens tubular in principle lodged vertically or longitudinally, so as
to give the structure buoyancy and to aid in breaking the force of a
running sea in conjunction with the ordinary screens or bulkheads before
described.
In witness whereof, I, the said Robert Saunders, have hereunto
set my hand and seal, this Twenty-third day of February,
in the year of our Lord One thousand eight hundred and
sixty-nine.
ROBERT SAUNDERS. (L.S.)