£78 Mr Buchanan's Report on the Bridge of Suspension 
open spaces between the other rows of chains are then filled up, 
so that this coupling forms a complete bearing on every one of 
the thirty-six chains which run on each side of the bridge, as 
seen in the section of roadway. Other forms might be pro- 
posed for this coupling, but I think it quite unnecessary to pur- 
sue these details any farther, and others of the same kind per- 
taining to different parts of the structure. In the present state 
of the business, it is impossible to specify every particular, and 
it is well known that in cases of this nature, the progress of the 
work usually points out in the details corrections and improve- 
ments which cannot be embraced in the original plan. It is 
sufficient here to describe the construction in such a manner as 
to lay down the general principles, which can afterwards be ap- 
plied in a variety of ways, to be more particularly considered 
when the work comes to be executed. 
On each side of the roadway there is a double rail of 4J feet 
high. This double rail consists merely of two single rails, each 
formed by connecting the lower part of the suspending rods to- 
gether, or filling up the space between them with smaller rods or 
wires, interweaving with each other diagonally, as shewn in the 
drawing. The two single rails being united by diagonal wires 
or frames, will form together a light, but strong and substan- 
tial railing, or fence, on each side of the bridge, and will also 
greatly add to the stiffness of the roadway. Such, then, is the 
general construction of the main-chains, the road-way, and the 
suspending rods or frames ; and although I have described 
them so minutely, I have yet omitted a multitude of details, all 
which, however, have been duly considered. 
The construction of the supporting-pillars is represented in 
the principal drawing. Each pillar consists of a pyramid with 
its pedestal, both of iron, and hollow within, resting on a strong 
pier or pillar of stone, and this founded on a broad platform of 
wood, supported on a series of piles driven deep into the soil. 
The pyramid is about four feet square at the top, and eight 
feet square at the bottom. The pedestal is 10 or 11 feet each 
way, and the height from the base of the pedestal, which is on 
a level with the roadway, to the top of the pyramid, is 60 feet. 
The pyramid and pedestal are formed of iron plates | inch 
thick, and cast with flanches, so as to be put together and bolt- 
