Lighthouses
The Eddystone Lighthouse
Smeaton's Design
The Eddystone rocks, in the English Channel off Plymouth, were a considerable danger to shipping in the seventeenth century. In 1698 Henry Winstanley succeeded in building a lighthouse on one of the rocks, and although secured to the rock by iron anchorage bars, the Winstanley structure was washed away in the hurricane of 1703. A second structure was put in place by John Rudyerd in 1708. The Rudyerd lighthouse was more securely attached, but it was built of timber, and it was destroyed by fire in 1755.
The third, and the most famous, Eddystone Lighthouse was completed by John Smeaton in 1759. It was made entirely of interlocked Portland stone, and took two years of work under the most difficult of conditions in the stormy channel.
The illustrations of the completed lighthouse are from Smeaton’s own account of the construction effort, published in 1791.
Foundation
Smeaton’s Eddystone Lighthouse was built of Portland stone. To secure the structure to the underlying rock, the lower courses were dovetailed, and set into corresponding dovetails that had been cut into the rock. For higher courses, the stones were carefully interlocked and pinned to the levels above and below. The resulting structure was extremely secure, and it withstood the battering of the sea for one hundred and thirty years. In the end, it was the rock below that began to fail, and not the lighthouse above it, and Smeaton’s tower was replaced in 1882 by a taller lighthouse on a nearby rock.
The illustration is from the second edition of Smeaton’s account of the building of the lighthouse, published two years after the first in 1793. It shows the plans for the six lower courses of the lighthouse, which when completed provided a level foundation for the rest of the tower.