250 Mr Stevenson’s Description of Bridges of Suspension. 
which forms the immediate approach to the roadway, measures 1 2 
feet in width, and 17 feet in height. Each pair of main chains being- 
suspended horizontally, pass through corresponding apertures 
in the masonry, at the distance of about £ feet above one another, 
and go over rollers connected with the building. The links 
of the main chains at these points are made as short as the 
strength or thickness of the iron will permit of their being weld- 
ed, in order that they may pass over the rollers, without distort- 
ing or unduly straining the iron. After going through the 
masonry of the pillar, the chains are continued in a sloping di- 
rection to the ground, as shewn in Fig. 4. Here they are sunk 
to the depth of 24 feet, where they pass through great ballast 
plates of cast-iron, into which they are stopped by a strong iron 
spear or bolt, of an oval form, measuring 3 inches by inches 
in thickness. The cast-iron ballast plates measure 6 feet in 
length, 5 feet in breadth, and 5 inches in thickness in the cen- 
tral parts ; but towards the edge, they diminish in thickness to 
2| inches. The ends of the chains thus fixed, are loaded with 
mound-stones and earthy matters, to the level of the roadway of 
the bridge. 
On the English side of the Tweed, the pillar or tower of ma- 
sonry forming the abutment or point of suspension, is built up- 
on a bench or foundation, excavated in the face of a precipitous 
sandstone rock, and is only about 20 feet in height, but its other 
dimensions correspond with the upper part of the masonry on the 
Scotch side. The chains on the English side are made to rest 
upon plates of cast-iron, included in the masonry, instead of rol- 
lers, as on the opposite side. Here the ballast-plates are of the 
same dimensions as those already described, but instead of being 
sunk into the ground, as on the Scotch side, their position is 
rather above the foundation of the pillar, where they are set 
nearly perpendicular, but are placed so as to correspond with the 
direction of the strain or weight of the bridge. For the greater 
security of the position of these ballast-plates on the English side, 
they are connected with a horizontal arch of masonry, which is 
dovetailed into the rock. This part of the work, however, was 
not in a finished state when the writer of this article saw it, at 
the ceremony of opening the bridge on the 26th of July 1820. 
Upon this side, the approach to the roadway forms a curve in 
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