proposed to be erected at Montrose. 269 
load or heavy body moving along the bridge, acts, not on one, 
but on all the chains together, and the effect being thus distri- 
buted over a greater mass, is much less sensibly felt. The 
roadway is suspended, or bound to the chains, by a series of 
iron rods, hanging vertically ; and I propose besides, 3dlv, To 
extend a similar series of rods horizontally, from the chains to 
the suspending pillars, so that these horizontal rods, inter- 
weaving with those which hang vertically, the whole space di- 
rectly under the chains, and between them and the roadway, 
will be filled up by a kind of net or wire work, on a large scale, 
and which, without interrupting the view, will yet commu- 
nicate a remarkable firmness and steadiness to the roadway, 
the reason of which may be easily shewn, and has indeed been 
experienced in the model which I have constructed. If these 
and other precautions are adopted, every unpleasant undulation 
in the roadway will be prevented. 
Since there is no intermediate bearing for the roadway be- 
tween the opposite main chains, it is evident that we have a 
stretch of 30 feet for our flooring, and that if we were to con- 
struct it in the common mode, with beams and planking, it 
would require extraordinary weight and strength of materials 
to withstand the cross strain arising from such an uninterrupted 
span between the opposite supports. We must here, therefore, 
adopt the principle of the roof, or something equivalent to it. 
I propose to sustain the whole weight of the roadway on a se- 
ries of malleable iron-bars, stretched at intervals of five feet be- 
tween the opposite sides of the roadway, and each hanging 
down three feet in the centre, in the form of a suspended arch, 
the extremities of these bars forming the points of suspension, 
and being attached to a cast iron socket, to which are also fixed 
the lower extremities of the suspending rods of the bridge ; so 
that, while the suspending rods bear up the sockets, the latter 
sustain the arched bars and the ’weight of the roadway to be laid 
upon them. But, as the roadway rises in the centre six inches 
above the sides, another bar of malleable iron, adapted to the 
curve of the roadway, is stretched above, and from each extre- 
mity of the hanging bars to the centre ; this bar springs from, 
and abuts against the cast iron sockets ; while the under bar 
is stretched by the weight of the roadway, and would, in conse- 
