At a distance of about four miles to the north of Othona, across the estuary of the River Blackwater, lies the island of Mersea. In the year 1896 some Roman foundations were accidentally discovered in the western part of the island which, upon examination, appear to have an important bearing on the Roman scheme of coast defence in this part of Britain. The foundations were circular, 65 feet in diameter, and closely resembling in gigantic form the steering-wheel of a ship. The foundations were of Kentish rag and chalk lime mortar, and above this the low walling was almost entirely composed of Roman bricks set in red mortar. Dr. Henry Laver, F.S.A., who communicated the discovery to the Society of Antiquaries of London,[7] modestly abstains from giving any explanation or theory as to the purpose of the building which stood on this site, but in the opinion of the present writer there seems to be little doubt that the foundations were intended to carry a lofty pharos, or perhaps signalling tower of timber by means of which messages might have been transmitted to Othona and Colchester. 4. REGULBIUM [Illustration: FIG. 4. RECULVER, KENT] Now known as Reculver, is situated about three miles to the east of Herne Bay. The site, although originally some distance inland, is now, owing to the encroachment of the sea, quite close to the shore. Indeed, about half of its area has been destroyed by the waves, and is now covered at high water. Its area when complete was over seven acres, and its walls which, in the eighteenth century, stood 10 feet high, and still remain to a height of 8 feet in some places, are no less than 8 feet in thickness with two sets-off inside. It seems doubtful whether there was ever a ditch round the castrum. Owing to the ruinous condition of the main part of the masonry, and the complete destruction which has overtaken the northern part of the foundations, it is impossible to ascertain any particulars as to the gates or internal arrangements. [Illustration: FIG. 5. ROMAN MASONRY, RECULVER, KENT Showing facing stones (squared), rubble core, and pebbly foundations] As will be seen from the accompanying ground-plan the form of the castrum at Reculver was quadrangular. The angles were rounded, but there are no indications of towers or bastions. These features are considered characteristic of Roman fortresses of early date. Another feature pointing to the same conclusion is the absence of tile courses in the walls. The only recorded facts about this fortress is a mention in the "Notitia," from which we learn that it was garrisoned by the first cohort of the Vetasians commanded by a tribune. [Illustration: FIG. 6. RECULVER: THE RUINS OF THE CHURCH]