The pharos on the western heights of Dover, of which little now remains, must have formed an extremely valuable auxiliary to that on the eastern heights, affording a guide for ships making at night for the haven of Dover. It is not at all improbable that both structures combined the purposes of lighthouses at night with those of signalling stations in the daytime. [Illustration: FIG. 10. PHAROS, DOVER] The precise details of the existing pharos, although of the greatest interest from architectural and archaeological points of view, are not necessary to our present purpose, but a few facts are worthy of notice. The masonry throughout is of tufa with the exception of two or three courses of Roman tiles at intervals of about 4 feet, and the foundations, which again consist of several courses of tiles arranged in three sets-off, and with an octagonal plan. The tower is of octagonal plan externally, and square within, where each of the four walls measures about 14 feet. The structure is believed to have been repaired and cased with flint in the year 1259, when Richard de Codnore was Constable of Dover Castle. His arms, Barry of six, argent and azure, are carved in stone on the north side of the pharos. The octagonal chamber in the top story of the tower appears to have been restored or rebuilt in Tudor times. It is interesting and instructive to compare the Dover lighthouses in their relation to the French coast and Richborough, with the signalling tower or lighthouse of West Mersea, by means of which communications were kept up with the sea-coast station and castrum of Othona. Bearing in mind the defensive character of the forts with which the lighthouses were associated, it seems probable that their purpose had a close relation to the work of watching the coast, and obtaining early information of the approach of invaders. There is a strong probability that more of such buildings for observing the approach of enemies once existed, traces of which have now perished. [Illustration: FIG. 11. PHAROS, DOVER] 7. PORTUS LEMANIS Situated originally on the side of a spur of high ground at Lymne, near Hythe, and overlooking the flat ground of Romney Marsh, was a fortified station of sufficient importance to rank as a town. Its distance from Dover, and its situation on the south coast, suggest that it cannot have formed a part of the group of contemporary fortresses which defended the east coast of Kent. Owing to a landslip on a large scale, which happened possibly before the Norman Conquest, the whole of the site upon which this town stood slipped downwards towards Romney Marsh, and the massive walls and towers by which it was once encompassed were disturbed, shattered, and overturned.