Mr. JOHN MASON (Member of Council), proposing the warmest thanks of the meeting to Dr. Gottfeldt for a fascmating presentation of the subject said, one had the impression that Dr. Gottfeldt, like Don Quixote tilting at windmills, had felt it necessary to set up a bogey against curved bridges in order to give himself an opportunity of shooting it down. It was perhaps a little hard on the Ministry to be picked to fill the role of the bogey. At any rate, Dr. Gottfeldt had given a very good reason why certain bridges lent themselves naturally to a curved shape. Mr. Mason recalled a photograph which had been shown of the bridge at Barnstaple, the reason for its curvature being that that enabled the piers to be brought into line with the flow of the water. In jetty work he had found it advantageous to keep the piers in line with the flow; and in those conditions the approaches or approach bridges lent themselves to curves.
When the first wrought-iron suspension bridges were constructed in this country-the most famous were the Menai bridge by Telford and the Clifton bridge by Brunel-there was naturally some scientific interest in their design and properties. The considerable flexibility of these bridges, leading in some cases to excessive deflections under railway loads, and in some others to lateral and vertical oscillations under high winds, tended to concentrate scientific interest on the deflections and vibrations of suspension bridges, and this is reflected in the literature of the time. But the severe effects of these oscillations, coupled with the increasing rolling loads on roads and railways, rapidly deterred responsible English engineers from the wi$espread use and further development of suspension bridges, and so we find that the early research work came to a premature end, and was not revived until some 90 years later, when proposals for bridging the Severn, the Humber and the Forth for road traffic brought long span suspension bridges to the fore in this country. Meanwhile, as is well known, there had been very considerable developments in suspension bridge design in the U.S.A., culminating in the Golden Gate bridge with a maximum clear span of 4,500 feet. That the decision to proceed with the design of the Severn bridge should have roughly coincided in time with the oscillatory failure of the Tacoma Narrows bridge may well be looked upon by future historians as fortunate for any long span suspension bridges to be built in England; it has certainly reawakened scientific interest in the behaviour of suspension bridges, and is of course the indirect origin of this paper. A.G. Pugsley