Mathematical Bridge

One of the most popular sites of our historical city, that customers look forward to seeing when joining a Cambridge punting tour, is the Mathematical Bridge. The Mathematical Bridge is very popular with tourists, the reason for this reputation could be due to the myths behind its’ construction. Whilst, others might say that its popularity comes from its unique structure, which grabs peoples attention. In actual fact, this Bridge has been a well documented sight by visitors dating back to the 18th Century, so its admiration stems from hundreds of years ago.

It’s “original” name was the Wooden Bridge or Essex’s Bridge, although these names are not now used when referring to this structure. This Bridge stands across the River Cam, connecting both courts of the famous Queens’ College. The red brick building to the side of the bridge is part of the oldest building on the river in Cambridge, containing segments of the President’s Lodge. This structure is also situated next to Silver Street Bridge, a site that dates back to the 14th century, a highway for general traffic throughout the years.

Traditional Punting Company Cambridge tours have always been a favoured way for people to explore Cambridge gems, including the Mathematical Bridge. The tour itself will take you along the middle section of the River Cam, passing seven Colleges and travelling under seven of the most iconic bridges, of which the Mathematical Bridge is one. The punt then turns at Silver Street Bridge before making its way back to the departure point. During this trip you will get close up views of the beautiful sights, creating great photos, whilst soaking up the details of the engineering and architectural designs.

Brief history of this Bridge

It was inevitable that any structure of wood would require repair. The original bridge that was constructed in 1749 was developing problems due to the decay of certain timber elements by the mid-19th century. Repair to the bridge took place in 1866, however, in 1905 the bridge was completely rebuilt to the same design, by a local builder, using teak instead of oak.

In this recent version of the bridge, fastenings are now visible at the cross-over between tangents, where no fastenings had been visible before 1905. Which could have then led onto the myth of a failed re-assembly of the original construction of the bridge, and the lack of fastenings in its original design.

The Myth

Even though this bridge has been well documented, there have been many false stories associated with it. The two myths that get the most attention are: that Sir Issac Newton designed the bridge and that the bridge was first built without fastenings at the joints.

It is believed, that Newton built this bridge using his understanding of mathematics and gravity; without using any nuts or bolts to hold it up (even though Newton died in 1727 and the bridge was built in 1749). The story goes that some students wanted to understand how he constructed a bridge that “consists of a single arch of woodwork, and so framed that, without a single nail to bind the pieces together, it is firmly supported”. So, they took the whole thing apart, but unfortunately, they didn’t manage to build it back together. That is why it has now nuts and bolts to hold it up. These stories were so popular in the 19^th Century that for some time it was known colloquially as Newton’s Bridge.

The Truth

The ‘Mathematical’ Bridge was actually designed in 1748 by William Etheridge, and built in 1749 by James Essex the Younger. Etheridge had previously been foreman to James King, master carpenter during the building of the first Westminster Bridge. King used an interesting system of tangent-and-radial trussing. Etheridge took over the work at Westminster after King’s death. This system was then applied to construct the Mathematical bridge. Which means that:

“the load bearing deck is supported by horizontal cross-beams attached to the bottom of the radials, close to the junction of two tangents, where the applied load can balance the resultant of the two compressive forces from the tangents.”