IMPROVEMENTS IN THE MODE OF AND APPARATUS FOR CONSTRUCTING BREAKWATERS, MOLES, AND OTHER UNDER WATER ERECTIONS
Year: 1864

page_text: LETTERS PATENT to Charles Liddell, of Abingdon Street, in the City of
Westminster, Civil Engineer, for the Invention of "IMPROVEMENTS IN
THE MODE OF AND APPARATUS FOR CONSTRUCTING BREAKWATERS, MOLES, AND
OTHER UNDER WATER ERECTIONS."
Sealed the 28th October 1864, and dated the 18th May 1864.
PROVISIONAL SPECIFICATION left by the said Charles Liddell at the
Office of the Commissioners of Patents, with his Petition, on the 13th
May 1864.
I, CHARLES LIDDELL, of Abingdon Street, in the City of Westminster, Civil
Engineer, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN THE MODE OF AND APPARATUS FOR CONSTRUCTING BREAKWATERS, MOLES,
AND OTHER UNDER WATER ERECTIONS," to be as follows:-
This Invention relates to the construction of breakwaters, moles, piers,
and other submerged or partially submerged buildings, with the aid of
blocks or large masses of masonry, beton, or concrete, the object being
to reduce the cost of constructing such works and ensuring great stability

page_text: thereto. To this end I employ cellular caissons of sufficient buoyancy
to float the blocks of concrete to the spot prepared for their reception, and I
then cause the caissons to deposit their load on the prepared foundation. In
constructing the caisson I first form hollow water-tight cellular boxes or floats,
using by preference for this purpose wrought-iron plates rivetted together
and strengthened in the ordinary way of constructing landing stages. These
boxes or floats I connect together by framing bolts or otherwise to form
either in part or wholly the walls of the caisson. These walls being hollow
water may be admitted thereto to sink the loaded caisson, and then withdrawn
therefrom to restore its buoyancy, and allow it to float away] from the
deposited load. The form of the caisson will depend upon the kind of work
in hand. Supposing it is desired to deposit blocks of beton, of a transverse
section corresponding to that of the sea wall which is required to be erected,
I build the side walls of the caisson of any suitable length, and I temporarily
attach thereto, by bolts or otherwise, a platform, which forms the bottom or
floor of the caisson. The ends I form by closing the space at the extremities
of the walls with planks or plate iron. In this way I provide an open floating
chamber, its cross section corresponding in form to the cross section of the
wall that is to be erected, and in this chamber as in a mould, I build up or
form the block of masonry, beton, or concrete. The blocks of concrete may
be formed in any sheltered situation convenient for the purpose, and in still
water either above or below the surface so as to ensure homogeneity and
solidity of construction.
In constructing a breakwater according to this Invention in a tideless sea of
say about 20 feet depth, I prepare the site by levelling it for the reception of
the blocks, and if of greater depth I first form an embankment of stone by
tipping it in the ordinary way of constructing embankments of "pierres
perdues," to within about 20 feet of the surface, but more or less according to
the locality, such depth below the surface being at a point at which no move-
ment will take place in the stones tipped in the ordinary way. In tipping
the stones I take care to level the surface on which the beton is intended
to rest to a nearly uniform level. The beton blocks which are to form the
upper part of the breakwater, and to rest on the bottom or on an embankment
of stone formed as described, may be made of any required dimensions, but I
prefer to make them of the whole transverse section of the upper part of the
breakwater as above mentioned, and of as great length as possible. When
the block is moulded and sufficiently set to withstand the action of the sea,
I float the caisson to the place where the block is to be deposited, and let

page_text: water into it sufficient to sink it, until the block settles on to the bed prepared
for it. The platform is then released from the caisson, and the water being
pumped out of the cells, the caisson is floated off the deposited block. The
caisson being now brought back to the sheltered situation, from which it
started another platform is fitted thereto, and in like manner another block is
moulded in the caisson, and when sufficiently set is deposited on the prepared
bed, in the manner above described.