Casquets lighthouses per ton of ship when vessels passed the rocks and in turn he paid Trinity House 50 pounds per year for the right to run the lighthouses. The lighthouses reverted to Trinity House in 1785. They were converted to oil lamps with metal reflectors which were first used on 25 November 1790; and upgraded again with apparatus to rotate a beam of light in 1818. This had a clockwork mechanism which was wound up every hour and a half and gave one flash every 15 seconds. The lighthouses were badly damaged and the lanterns smashed in a severe storm on
History of lighthouses Tower of Hercules at A Coruña and the ruins of the Dover lighthouse in England give insight into construction; other evidence about lighthouses exists in depictions on coins and mosaics, of which many represent the lighthouse at Ostia. Coins from Alexandria, Ostia, and Laodicea in Syria also exist. While the evidence provides insight into the exterior structure of these structures, there are many gaps in evidence concerning less visible aspects of the structures. The remains at A Coruña and Dover help determine how each lighthouse structure functioned, though one must make some assumptions to determine how the structures beacons were