Part of Queen’s College in Cambridge, the Mathematical Bridge is one of the most recognisable features of Cambridge’s colleges. Connecting the old and new parts of the college together, it is constructed of straight-segmented timbers bolted together to create the impression of an arched bridge, defying the mid-eighteenth century engineering principles at the time.

A truly remarkable piece of engineering for its time, today the bridge attracts thousands of tourists each year. We take a look at its history and how it came to be. 

Firstly a few facts:

• Although we know it as the ‘Mathematical Bridge,’ there is actually no official name for the bridge. The name derived from the fact that the bridge is built with entirely straight timbers, despite maintaining an arched shape. The term ‘Newton’s Bridge’ arrived, grown from myths that Newton had designed it, though this of course is not true.
• Though it was designed by William Etheridge, the credit largely falls on James King who defied the engineering odds to construct the bridge.
• As wood is weak when bent, the bridge is constructed of short straight lengths of timber, with the single dominant force being compression (in which state, wood is very strong!)
• The lack of in-fill on the sides of the bridge reduces the impact of side-winds, with only cross-bracing sitting underneath the footway, making it durable during stormy weather.
• When he designed it, Etheridge claimed that if the timber ever needed to be replaced, then it could be removed without having to dismantle any other part of the bridge. This, so far, has never been tested in practice.

1748: A known foreman carpenter on Old Westminster Bridge, William Etheridge is asked by James Essex the Younger (a Cambridge builder) to design and build a model of the Mathematical Bridge for the sum of £21. The design he created was a scaled down version of his previous design, Old Walton Bridge in Surrey. 

1749: The bridge is constructed during the same time as the brick walls which align the riverbanks, as well as during the alterations which took place in changing the layout of the Grove, making it hard to distinguish when exactly the building of the bridge was completed.

However, historians believe that it was the summer of 1749 when the bridge was constructed.

1850-56: Roughly one-hundred years on, the original bridge of 1749 seemed to be decaying, with the cross-beams succumbing to water clogging and thus, causing the wooden decking to sag. To solve the problem, additional layers of cross-beams were added to the construction, though the bridge by now was appearing to be leaning inwards from the weeping wood.

1866: The bridge was repaired properly, removing the old damaged cross-beams and replacing the stepped-decking with sloped decking, allowing for trolleys and wheelchairs to use today.

1905: The bridge is completely rebuilt by local builder, William Sindall, who constructed the bridge out of teak instead of oak. At the same time, work was also being carried out - like originally - to the riverside buildings.

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