Coox.—On the Construction of the Brunner Gorge Bridge. 315 
a fraction whose value will be found, on calculation, to be somewhat less 
than 1:01. It follows, therefore, that by adopting the construction ex- 
plained in the foregoing part of this paper, the tension of the chain at the 
anchor-plate was not increased by more than one per cent. 
It might, perhaps, have been legitimate to assume that the chain would 
liein a plane curve; and then, by reasoning similar to that used in the more 
usual case of a suspension bridge, it might easily be proved that the curve 
would be a parabola. But the method above given is perfectly general, and 
can readily be applied to the case in which the middle point of the chain is 
not attached to the floor of the bridge, but is a given height vertically above 
it, and in which the suspending rods are not in the same plane. Upon 
examination, the equations of equilibrium will be found to be integrable in 
this case also. 
I now wish to call attention to what appear to me to be serious defects 
in this bridge. 
1. If there should have been any swaying of the bridge from side to 
side, inasmuch as the supporting chains did not hang in a vertical plane, 
there would have been a tendency to throw a great deal more than its due 
share of the burden on one chain. Mr. O'Conor, the District Engineer, 
says in the memorandum to the Commissioners, which forms Appendix A, 
attached to this Report :—‘ On the 24th of the month (three days before the 
accident) there was a heavy gale blowing down the gorge, which caused the 
bridge to sway to the extent of about six inches from side to side." In 
such a case the windward of the two ropes would be unduly tightened, 
whilst the leeward one would have its tension suddenly diminished. The 
windward rope therefore would be in a very abnormal state of tension, and 
if the wind came in sudden and violent gusts, as I believe constantly 
happens in mountain gorges, the increase in tension of one rope and 
decrease in the other would be sudden, and might, I conceive, be disastrous 
to the bridge. 
I must mention, however, that it was contemplated to fix cross-braces, 
which it was expected would counteract the swaying completely, but these 
had not been fixed on the 24th when the swaying above alluded to was 
observed, nor do they appear to have been fixed at the time of the accident. 
2. Each rope was made up of two sorts of material. The Commis- 
sioners’ Report says :—‘‘ Each chain was to be composed of seven twisted 
wire ropes four and a half inches in circumference, laid side by side, and 
above these six other ropes, each made of thirty telegraph wires spliced 
together but not twisted, placed side by side, the whole united every ten feet 
by clips, forming a flat chain twelve inches in width, by two inches in depth.” 
Each rope therefore consisted of two portions entirely different from each 
