Keywords: Shape – Materiality – Construction
For John Smeaton’s oeuvre „A narrative of the building and the description of the construction of the Eddystone Lighthouse with stone“ I chose the concept of Innovation.
The Author of the Book, John Smeaton, is often regarded as the father of civil engineering. He designed the third lighthouse, built from 1756-59, on the Eddystone. The tower was 22m high and measured 7.6m at the base. The construction was very impressive and Smeaton was then asked to write an account of the construction of the lighthouse. As I mentioned in a post before, the Book has a written part and some drawing and plans in the end. The first part starts not only with a description of his own tower, but also of the two previous ones, build by Henry Winstanley and John Rudyerd. The first was destroyed by a great storm and the second by fire. Smeaton’s Tower stood until it was replaced by the present structure, designed by Sir James N. Douglass.
Smeaton had the intention to build a lighthouse, which can’t be destroyed by the sea and fire. He considered the problem of constructing a lighthouse at sea and came up with some breaking ideas.
As an inspirations he took the shape of an oak tree, a large heavy base rooted in the soil with a curved tapering pillar above. A very innovativ aspect because the tapered shape provided stability and reduced wind loads. He decided to build it entirely in stone and not out of wood like his predecessors. For the foundations Smeaton used local granite.
Furthermore he developed a quick drying cement that would set under water. Very essential in the wet conditions and a formula which is still used today. He was the pioneer who used pebbles and powdered brick as aggregate to get an hydraulic cement. An other innovative method was to secure each block of stone by the dovetail masonry and marble dowels.
The upper part of the tower is extra stabilized by an endless iron chain which was set into a groove in the outer wall and poured over by molten lead. Smeaton’s idea for additional security was inspired by Wren’s design for the cupola of St Paul’s Cathedral where an endless chain contains the thrust of the dome.
What I want to emphasize is, that his whole construction was an astonishing achievement and a milestone in history. This is why I chose the concept of Innovation.