Stone Lighthouses

The modern era of lighthouses began at the turn of the 18th century, when increasing transatlantic trade required the construction of efficient lighthouses. Lighthouses now had to be built far off the coast. To make this possible, a construction technique was developed in which the lighthouses were built using large blocks of stone. The interlocking shape of the stone blocks meant that the tower stood like a monolithic large block of stone in the sea.

The production of the granite blocks with dovetail joints by stone masons was a major achievement. The finished stone blocks were preassembled on land to check the fit. The masonry was then taken apart and transported by ship to the construction site.

The first lighthouse made of interlocking masonry blocks was built in 1759 on the Eddystone Rocks reef off Plymouth, England. The interlocking masonry blocks remained the most important material for the construction of lighthouses until they were replaced by reinforced concrete construction in the 20th century. The construction of lighthouses led to numerous technical innovations. New cranes were developed, railroads for moving the stone blocks and new mortar compositions.

John Smeaton (8. Juni 1724 - 28. Oktober 1792) was a British civil engineer who was responsible for the design of bridges, canals, harbors and lighthouses. He was also a skilled mechanical engineer and an eminent physicist. Smeaton was the first self-proclaimed "civil engineer". He pioneered the use of hydraulic lime as a binder in mortar exposed to the sea.

John Rennie, (born June 7, 1761, Phantassie, East Lothian, Scotland—died October 4, 1821, London, England), Scottish civil engineer who built or improved canals, docks, harbours, and bridges throughout Britain.

Robert Stevenson was responsible for the design and supervision of more than 25 lighthouses, including the Bell Rock Lighthouse in 1811. Not only did the structures have to be designed to withstand the great forces of nature - waves, currents and wind - but the designer also had to design the construction method and lifting equipment etc. required to build a monolith, usually on a rock in the middle of the ocean and sometimes far offshore.

Francis Watt, Foreman and millwright who made the development and construction of various technical facilities for the construction of lighthouses possible. He developed a railroad that made it possible to transport the stone blocks from the landing stage to the tower construction site (and later influenced the development of the railroad on land) and various lifting devices that made it possible to lift and precisely move the stone blocks.

Engineer: John Smeaton, mathematical instrument maker and civil engineer

After several wooden and metal lighthouses had been destroyed by storms, John Smeaton, an instrument maker and mathematician, was commissioned in 1756 to design a robust construction for the lighthouse. Smeaton suggested that the lighthouse be built of stone and shaped like the trunk of a tree, wider at the bottom, tapering towards the top.

Work on site began in 1756, starting with the foundation being hewn out of the reef and interlocked with the stone blocks. Construction work was interrupted in winter. During this time, the stonemasons prepared the stone blocks for the lighthouse on land. Granite from Cornwall was used for the blocks of the outermost stones. Blocks of limestone from Portland were used for the core of the tower. Each stone block weighed over a ton. In addition to the innovative construction technique with interlocking stone blocks, Smeaton was the first to use hydraulic lime (as a precursor to cement) to fill the joints between the stone blocks. Construction of the lighthouse lasted until 1759.

Smeaton's lighthouse was 18 m high and had a diameter of 7.9 m at the base and 5.2 m at the top. The lighting consisted of 24 large tallow candles.

In 1877 the tower had to be replaced as the rock underneath the lighthouse eroded away. The original lighthouse was dismantled and rebuilt at Plymouth.

Archive.org "A narrative of the building and a description of the construction of the Edystone Lighthouse with stone"