Engraving showing two early designs by Robert Stevenson (1772-1850) for the Bell Rock Lighthouse. On the left is a masonry lighthouse with an exposed spiral staircase winding up the outside of the lighthouse base. On the right is a cast-iron lighthouse that would have been supported on nine legs. The cast-iron lighthouse would have been at more risk of collapse should a vessel have sailed into it than a freestanding masonry lighthouse. Illustration from Stevenson's 'An account of the Bell Rock Light-house: including the details of the erection and peculiar structure of that edifice; to which is prefixed a historical view of the institution and progress of the Northern Light-houses', published in Edinburgh in 1824.
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