54 
On Bridges of Suspension. 
sion, formed of ropes or bamboo canes, and in those constructed 
of common chain, as well as in a variety of objects which must 
be familiar to every person of common* observation. But those 
simple contrivances, which have been noticed by some writers, 
have no more resemblance in their construction to the bridges or 
piers of suspension which have been erected in Great Britain, 
than the rude bridges of remote ages, which consisted of logs 
supported on props, are to be compared to the architecture of 
modern times. 
44 The first bridge of suspension that we hear of in this coun- 
try, is the one thrown across the river Tees, in the county of 
Durham, the span of w 7 hich does not, I think, exceed 80 feet 
It is formed of two common chains, stretched over the river, 
from abrupt banks, with battens laid across, and boarded, the 
gangway partaking of the curve of the chains. 
44 Such an arrangement is evidently a bad one, inasmuch as 
we must ascend to the points of suspension, then descend, and 
rise according to the curve of the chain, which, in that which I 
have usually adopted, would be a pull of one foot in seven. 
This is hardly practicable, and my earliest attention was em- 
ployed to remedy the evil. In 1814 I erected a bridge, with 
the road or platform perfectly horizontal, on my premisses at 
Mill-Wall, where it still remains. This is effected by intro- 
ducing perpendicular rods through the joints of the main sus- 
pending bars, and adjusting their length to the curve above, so 
that they form a series of straps for the reception of a row of 
bars on each side, placed edgewise, and extending the whole 
length of the bridge, parallel to the entrance. The beams being 
laid across these bars, the platform or road becomes quite hori- 
zontal ; or an ascent frtay be given from the sides to the middle, 
in the same plane as with the roads leading to the bridge. The 
span is 105 feet, and the iron-work only weighs 38 cwt. It was 
inspected by the late Mr Bennie and Mr Telford, who drove 
their carriages over it ; and it has been considered by men emi- 
nent for their skill in mechanics, as a remarkable combination 
of strength and lightness. 
44 The advance to improvement in this new era of bridge- 
building, may be traced to the invention of iron-cables, which 
* An account of this bridge is given in pages 238 and 239 of Vol. V, of the 
Edinburgh Philosophical Journal. — Edit. 
