276 Mr Buchanan’s Report on the Bridge of Suspension 
In the drawing already referred to, the bridge is represented 
with the draw-bridge down ; but Fig. 4. shews also the situa- 
tion of the draw-bridge when raised to let a vessel pass. The 
space which in the principal drawing appears, and on most oc- 
casions will really be filled up by the suspending and cross rods, 
and by the side rails, &c. is, in Fig. 4, when the draw-bridge is 
up, quite open. All these parts are here formed in two frames 
or leaves, which, turning on hinges, fold inward from each side 
to the centre of the bridge, while the roadway part, being made 
of the slightest and simplest construction, is drawn up by a 
rope passing over a pulley within each pyramid, and round a 
barrel within the pedestal, which is turned by a winch applied 
to the axis when necessary. When the draw is up, the chains 
being of sufficient height, there is then nothing to prevent ves- 
sels passing under them with ease. This part of the work will 
present no difficulty. But to prevent vessels from striking the 
roadway while the draw is up, the present wooden pier must be 
retained and strengthened. For the sake of a more uniform 
appearance, a similar pier should be retained on the north side, 
and this might also be turned to a useful account. For if a 
row of sheet piling were driven along this pier, and projecting 
on each side with a sweep to landward, the enclosed space might 
be filled up with sand and gravel, and thus effectually protect 
the foundation of the present pier of stone. I consider an ad- 
ditional pier of stone for the draw-bridge, on the south side, as 
wholly unnecessary. 
Such, then, is the structure now proposed, in lieu of the pre- 
sent w r ooden bridge, and if it be executed with care, and with 
due attention to the principles I have laid down, there can be no 
doubt of its strength and solidity, while it will form an addi- 
tional ornament to the scenery of the place, and will be a work 
altogether worthy of the present advanced state of society and 
art *. 
Edinburgh , 15th February 1823. 
Geo. Buchanan. 
* Since the above Report was written, I last summer visited the great 
bridge of suspension which is now erecting at Bangor Ferry, over the Straits 
of Menai, and there obtained much interesting information regarding this 
