AN IN- PROVED BRIDGE
Year: 1864

page_text: PROVISIONAL SPECIFICATION left by George Haseltine at the Office of
the Commissioners of Patents, with his Petition, on the 15th February
1864. A communication from abroad by George H. Bruce and Samuel
S. Shinn, both of Lancaster, Erie County, New York, United States.
I, GEORGE HASELTINE, of the "International Patent Office," No. 12,
Southampton Buildings, Chancery Lane, in the County of Middlesex, Civil
Engineer, do hereby declare the nature of the said Invention for "AN IN-
PROVED BRIDGE," a communication :-
The nature of said Invention consists chiefly in the novel combination
of two bridge frames to form one bridge, one of which frames is designated
the "arch frame," and the other the "truss frame," each being a complete
self-supporting structure, and in the employment of a tongued wedge with
each pair of principal rafters at their apex for the purpose of filling the space
left between the ends of said rafters in such a manner as to compensate for
any shrinkage of the timbers, or any sagging of the bridge, as well as to pre-
vent any side slip to the rafters. The arch frame is composed of several arch
beams framed together at their contiguous ends and truss braces or principal
rafters, which rafters are placed in pairs and stepped on the said beams at the
foot. There is a pair of rafters for each beam, and suspension rods which
sustain the swing beams forming a part of the truss frame. The truss frame
is composed of the truss braces or principal rafters arranged in pairs and
stepped on to the said swing beams at the foot with suitable tie rods and
suspension rods which sustain central swing beams. Each of the tie rods are
of sufficient length to pass through three of the swing beams in a manner to

page_text: tie together the two beams upon which each pair of the rafters of the truss
frame is stepped. These swing beams are so placed, when the two frames are
united, that one of them will be directly under the apex of each pair of the
principal rafters of either frame, so that the suspension rods which drop down
from the top of the principal rafters of the "arch frame" will sustain the
swing beams on which the rafters of the truss frame are stepped, and those
that drop down from the top of the rafters of the truss frame sustain the
central swing beams. A strengthening metal piece is placed across the con-
tiguous ends of the arch beam and extends on to the foot of the principal
rafters; bolts passing through each of these pieces and through the arch
beams form stirrups under the central swing beam, which stirrups bind the
two frames together. The rafters are made a little short with grooves in their
contiguous ends in order to admit a wedge having a tongue upon either side.
The wedge must be driven in tight when the bridge is built, and is made of
sufficient length and thickness to be driven in and kept tight in case of any
subsequent shrinkage of the timbers or any sagging of the bridge. By this
means, in -connection with the suspension and tie rods, the timbers of the
bridge may at all times be kept tightly together so as to produce an equilibrium
of strain upon all parts of the bridge, and so that the bridge shall not at any
time become weakened by occasion of loose and unfitting joints. This wedge
will also, by reason of its tongues fitting into the groove made in the end of
the rafters, prevent any side slip of the rafters. The end of the arch frame
rests on the abutments and should lap on the abutments sufficiently far to
allow the ends of the truss frame to also rest on the-abutments, or at least
to come very near said abutments.