Mathematical Bridge
A timber footbridge at Queens' College that looks like an arch but is built entirely from straight beams.
In the south-west of the city centre, a timber footbridge over the Cam links the two halves of Queens' College; this is the Mathematical Bridge, although officially it goes by the plainer names Wooden Bridge and Queens' Bridge. It stands roughly a hundred feet north-west of Silver Street Bridge and is Grade II listed.
Straight timbers, curved result
William Etheridge designed the bridge and James Essex built it in 1749. It has been rebuilt twice, in 1866 and 1905, but the overall design has been kept. The span looks like an arch, yet every piece of timber is straight. The beams run as tangents that trace the curve, tied together by radial members that make the structure rigid. This tangent-and-radial trussing is the source of the name: the tangents mostly take compression and the radial pieces take tension, with very little bending.
Myths worth knowing
The best-known story says Isaac Newton designed the bridge and built it without nuts or bolts, and that students or fellows who took it apart later could not reassemble it without adding them. In fact Newton died in 1727, 22 years before the bridge existed, and fastenings were part of the design from the start; iron spikes had been hammered in from the outer face, hidden from anyone walking between the parapets, which is how the legend gained its footing.
Other points of interest
The first bridge of this kind spanned the river where Garret Hostel Bridge now stands, in the gap between Trinity and Trinity Hall. A replica was built in 1923 near Iffley Lock in Oxford.
Practical notes
The bridge is within the college grounds, so check Queens' own visiting arrangements.
Nearby
Within a few minutes' walk
