Mr Stevensoifs Description of Bridges of Suspension* £45 
The utility of Dryburgh Bridge, when compared with a 
troublesome ferry, even on the short experience of six months, 
had given it such a decided preference to the boat, that his Lord- 
ship, without hesitation, directed that it should be immediately 
restored : this was accordingly done, after a better design, for 
the additional sum of about L. ££0, and in less than three 
months it was again opened to the public. This bridge is now 
constructed upon the catenarian principle, agreeably to Fig. 3., 
the roadway being suspended by perpendicular rods of iron, 
from main or catenarian chains. The chief mechanical altera- 
tions upon the former plan consist in welding both eyes or ends 
of the links, instead of having one of them simply turned round, 
and fixed with a collar ; the roadway has also been strength- 
ened by a strongly trussed wooden rail, which also answers 
the purpose of a parapet, on each side of the bridge, the good 
effects of which were particularly exemplified, while the bridge 
was building. A high wind having occurred before the side- 
rails were erected, one end of the platform was lifted above the 
level of the roadway, and the undulating motion produced on 
this occasion is described as resembling a wave of the sea ; an 
effect which pervaded the whole extent of the bridge, and went 
off with a jerking motion at the farther end. But after the 
side-rails were attached, this vertical motion was checked, and is 
now found to be greatly reduced. There were also added to 
the newly constructed bridge at Dryburgh, guys or mooring- 
chains, consisting of rods of iron fixed to stakes in the opposite 
banks of the river. These guys are attached to the beams of 
the roadway, as shewn on the plan connected with Fig. 3. 
These diagonal moorings are said to have some effect in lessen- 
ing the motion of the bridge in high winds, but it did not ap- 
pear to the writer of this article, when he examined the bridge 
in 1820, that these guys could act in any very sensible degree 
in this respect. 
We have already stated generally, that the new bridge at 
Dryburgh is erected upon the catenarian principle. It may 
further be described as consisting 1 of four main chains, which 
are suspended in pairs between the points of suspension, in a 
horizontal position relatively to each other ; the lowest part of 
