Description The 70 foot tall lighthouse, designed by David (1815-81) and Thomas (1818-87) Stevenson, was built in 1857. Thomas Stevenson was the father of the author Robert Louis Stevenson (1850-94).When first built the light itself was fuelled by sperm whale oil, and displayed a central white beam flanked by a red and a green beam.It was not until 1898 that the lamp was converted to a paraffin vapour system, with Eilean Bn holding the storage tanks for the paraffin. These tanks were refuelled by a tripod housing a fuel valve, on the shore. A large mooring hook is still present beyond the tripod and can be seen from the path going along the north side of the island. A similar arrangement is present on the coast facing Kyleakin. The refuelling points were placed on the north and south sides of the island as a greater depth of water on those sides allowed the larger boats to berth.In 1960 the lamp was converted to run on acetylene gas. Acetylene gas was a much cleaner fuel and did not require constant pressurization, so the lighthouse no longer needed to be manned all the time. With the departure of the full-time keepers, the island cottages were then put up for sale by the owners, the Northern Lighthouse board. The lighthouse was finally decommissioned in 1993. The channel into Loch Alsh was then marked by the large red and green buoys that can be seen running east and west from the lighthouse. After decommissioning the lighthouse was denoted as a day mark, which means that it remains a landmark that it is used for navigation during the day, and must therefore continue to be kept in good condition.