BRI 
iflg from the" abutments towards the centre 
of the bridge. There are also diagonal iron 
bars, which are laid on the tops of the ribs, 
and extended to the abutments to keep the 
ribs from twisting. The superstructure is a 
strong frame of timber, planked over to 
support the carriage-road, which is com- 
posed of marl, lime-stone, and gravel, with 
a cement of tar and chalk immediately up- 
on the planks, to preserve them. The whole 
width of the bridge is 32 feet. The abut- 
ments are masses of almost solid masonry, 
24 feet in thickness, 42 in breadth at bot- 
tom, and 37 at top. The south pier is 
founded on the solid rock, and rises from 
about 22 feet above the bed of the river. 
On the forth side the ground was not so fa- 
vourable, so that it was necessary to carry 
the foundation 10 feet below the bed. The 
weight of the iron in this extraordinary fa- 
bric amounts to 260 tons ; 46 of these are 
malleable, and 214 cast. The entire ex- 
pense was 27,000 1. 
The splendid example of the bridge at 
Wearmouth gave an impulse to public taste, 
and caused an emulation among artists, 
which has produced many examples, and 
more projects of iron bridges. The Coal- 
brook Dale Company have constructed se- 
veral, among which is a very neat one over 
the liver Parrot, at Bridgewater. Mr. Wil- 
son, the engineer, employed by Mr. Bur- 
don, has also built several, and some years 
since finished a very elegant one over the 
river Thames, at Staines, which is by far 
the most complete in design, as well as the 
best executed, of any that has hitherto been 
erected. This bridge consists of a single 
arch, 181 feet in span, and 16 feet 6 inches 
in rise, being a segment of a circle of 480 
feet. The blocks, of which the ribs are 
composed, are similar to those in the Wear- 
mouth bridge, except that these have only 
two concentric arcs instead of three, as at 
the latter. The arcs are cast hollow, and 
the block connected by means of dowels 
and keys ; thus obviating the great defect 
observed at Weannout.h, of having so much 
hammered iron exposed to the action of the 
air. Four ribs form the width of the arch, 
which are connected together by cross 
frames. The spandrels is filled in with 
circles, Which support a covering of iron 
plates an inch thick : on this is laid the 
roadway 27 feet wide. Two hundred and 
seventy tons is the weight of the iron em- 
ployed in the bridge, and three hundred and 
thirty of the road-way, 
Public bridges, which are of general 
BRI 
conveniency, are of common right to be 
repaired by the inhabitants of that county 
in which they lie. Where a man makes a 
bridge for the common good of the King’s 
subjects, he is not bound to repair it. No 
one can be compelled to build, or contribute 
to the charges of building any new bridge, 
without act of parliament : and if none are 
bounden to repair by tenure of prescription 
at common law, then the whole county or 
franchise shall repair it. 
Bridges, pendent or hanging, called also 
philosophical bridges, are those not sup- 
ported by posts or pillars, but hung at large 
in the air, sustained only at the two ends 
or hutments. 
Bridge, draio, one that is fastened with 
hinges at one end only, so that the other 
may be drawn up ; in winch case the bridge 
stands upright, to hinder the passage of a 
ditch or moat. 
Bridge, flying or floating i is generally 
made of two small bridges, laid one over 
the other in such a manner, that the upper- 
most stretches and runs out, by help of cer- 
tain cords, running through pullies placed 
along the sides of the under bridge, which 
push it forwards, till the end of it joins the 
place it is intended to be fixed on. 
Bridge of boats, boats made of copper, 
and joined side by side, till they reach 
across a river, which being covered with 
planks, are fastened with stakes or anchors. 
Bridge of communication, is that made 
over a liver, by which two armies, or forts, 
which are separated by that river, have a 
free communication with one another. 
Bridge, floating, a bridge made use of, in 
form of a work in fortification, called a re- 
doubt, consisting of two boats, covered with 
planks, which are solidly framed, so as to 
bear either horse or cannon. 
Bridge, in gunnery, the two pieces of 
timber which go between the two transoms 
of a gun carriage, on which the bed rest. 
Bridge, in music, a term for that part 
of a stringed instrument over which the 
strings are stretched. The bridge of a vio- 
lin is about one inch and a quarter high, 
and near an inch and a half long. 
BRIEF, in common-law, a writ whereby 
a man is summoned or attached to answer 
any action, It is called brief, because it is 
couched in a few words, without any pream- 
ble. Brief is also used for a writing issued 
out of any of the king’s courts of record at 
Westminster, whereby something is com-, 
manded to be done, in order to justice, or 
the execution of the king’s command. 
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