IMPROVE- MENTS IN BRIDGES AND VIADUCTS
Year: 1865

page_text: PROVISIONAL SPECIFICATION left by Charles de Bergue at the Office
of the Commissioners of Patents, with his Petition, on the 15th December
⚫ 1865.
I, CHARLES DE BERGUE; of No: 10, Strand, in the City of Westminster,
Engineer, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN BRIDGES AND VIADUCTS," to be as follows:-
My Invention consists in constructing bridges and viaducts with piers or
supports grouped, disposed, or placed with regard to the lengths or spans
between them as herein-after specially set forth, and in combination with
girders having cantilever continuations or extensions in one direction or in
both directions beyond the length or span between two piers, such cantileve
extensions being constructed with progressively decreasing depth or quantity
of material towards their extremities; and for convenience of definition I
herein designate the combination of one such girder with its extensions and
its two piers or supports as an "independent cantilever structure." Subject
to the limitation herein-after specified the special grouping, disposition; or
placing of the piers or supports above referred to consists in the piers or

page_text: supports of two adjoining "independent cantilever structures "being erected or
placed so to bring into juxtaposition a cantilever extension of the girder of each
such structure as that the two extensions may together serve to bridge over or
cover a length or span equivalent, or nearly so, to the joint amount of their
separate lengths the connection between the ends of the "independent canti-
lever structures" being so effected as not to hinder their free expansion or con-
traction, nor destroy the independent structural character of either of them, nor
to cause the said two structures in respect of horizontal strains to become one
or a continuous structure. A viaduct or bridge thus constructed is intended
to have narrow spans intervening between the wide spans, bridged over by the
cantilever extensions, the said narrow spans being situate between the piers or
supports of each "independent cantilever structure," the limitation above referred
to being that the length of girder between the piers or supports on which it
rests, together with its cantilever extension in one direction, shall preponderate
or more than balance the cantilever extension in the opposite direction, and it
is deemed desirable that it should also balance or nearly balance such last-
mentioned cantilever extension when the same is loaded. For the purposes
of this definition the abutment at the extremity of a bridge or viaduct may be
deemed a pier, and the anchoring or tying down of the girder to such abutment
be deemed as replacing or as constituting a portion of the preponderance
described. To prevent misapprehension it may be stated that the above
.definition refers to one line or set of girders applied in the line of a bridge
or viaduct, and that according to the width or other requirements of an
intended bridge or viaduct two or more lines or sets of girders may be employed
with any appropriate cross girders, framing, or intermediate work: The
above referred to connection' of the ends of the independent cantilever
structures may consist of a plate or plates applied vertically, or nearly so,
to the ends of the cantilever extensions to be connected, the upper end of the
plate or plates being rivetted or fixed to one cantilever extension and the
lower end to the other cantilever extension, so as to allow horizontal expansion
or contraction of the independent cantilever structures to take place freely,
the ends of the cantilever extensions being nevertheless held by the said plate
or plates-evenly opposite to each other, and so that a load on either cantilever
extension may be partly supported by the other cantilever extension, the
vertical strain induced by the said load being transmitted through the said plate
For plates; and after a similar method a plate or plates may be applied to
prevent lateral horizontal movement of the end of one cantilever extension
without a corresponding movement of the end of the cantilever extension in

page_text: juxtaposition therewith, or the same plate or plates which serve the purpose
of transmitting the vertical strain may be arranged to prevent the lateral
horizontal movement without hindrance to free expansion or contraction of
the independent cantilever structures..