MARINE BIOLOGICAL STATION AT PORT ERIN. 147 



held it against him for more than three weeks. The oldest 

 portions of the existing walls are doubtless the under- 

 ground chambers of the tower at the entrance. The Keep 

 is of the Edwardian type of concentric castles, as dis- 

 tinguished from the solid square keep of earlier ages : some 

 architectural details point to the middle of the 14th cen- 

 tury, but so far neither the exact period nor the builder has 

 been determined. Its height at the entrance is 74 feet, the 

 nag-tower 80 feet from the present surface, which has been 

 filled in to a considerable depth. The thickness of the 



*''**«, 



Fig. 47.] Keeil of St. Trinian, Marowii. From a sketch*by Sir H.KDryden. 



walls is from T to 12 feet. At its northern extremity is a 

 lofty portcullis, passing which one comes to an open 

 quadrangular court, with a well in the centre. Outside, 

 at a short distance is an embattled wall 25 feet in height 

 and 9 feet thick, with several square towers at irregular 

 intervals. Exterior to this was a fosse or moat, now filled 

 up, outside of which is the glacis said to have been added 

 by Cardinal Wolsey, when guardian to Edward, third Earl 

 of Derby. On this were three low round towers or 

 redoubts, of which one remains on the north-west side near 



