278 Mr Buchanan’s Report on the Br idge of Suspension 
have merely, therefore, embodied the additional particulars, 
which have suggested themselves as corrections in that Report. 
The only alteration which deserves mention, is in the construc- 
tion of the frame- work of the road- way, which I now propose to 
form almost wholly of malleable iron, on account of the low price 
of this material, and the improvements which have been intro- 
duced in the rolling of it. This construction will reduce very 
considerably the weight of metal, while the frame-work will be 
equally strong, and much less liable to breakage. In regard to 
the principles on which the above Report is founded, I have 
taken the liberty, for the satisfaction of the Commissioners, to 
consult Professor Leslie, and have received from him the fol- 
lowing opinion, approving of the plan, and confirming all the 
opinions I have been able to form on the subject, by his great 
authority. Having now also received more accurate information 
respecting the mason-work, and other particulars of expence, I 
annex a corrected estimate, with confidence that the total sum 
there stated will cover all the expences proposed. In proof of 
which, I beg to submit the following letter, which I have re- 
ceived from a very respectable practical engineer, Mr Neilson. 
of Glasgow. G. B. 
66 College of Edinburgh , 1 1th Febr uary 1824. 
66 I have read over with very great satisfaction Mr Buchanan’s 
able Report : it is clear, full, and scientific, yet combining sound 
maxims of experience with the principles of accurate theory. In 
every essential particular, it appears eminently distinguished 
above ordinary reports. 
“ My approbation is the more hearty and unqualified, since I 
find that Mr Buchanan has adopted my suggestion, to lower the 
depression of the bridge, and thereby lessen the strain on the 
chains. By making that depression the eighth, instead of the 
fourteenth, part of the whole span, as commonly followed, he 
whole structure a very magnificent appearance. Above the roadway the sus- 
pending pillar is built solid, excepting two arched passages for the entrance 
and exit of carriages. At the roadway, it is about 38 feet across the bridge, 
by 28 feet in the length. At the top it is 34 feet across, by 9 feet. The 
stones are bound with iron dowels running vertically through them, and bed- 
ded in Homan cement. The roadway is to be of wood, supported on malleable 
iron-frames. 
