Here are shown the bronze mortars, formerly placed in the Gun Park, with other pieces of ordnance.
At the south end is a mortar of nine bores used for fireworks at the peace of Aix la Chapelle in 1748. Near to this is a ship's gun dredged from the wreck of HMS Royal George, sunk by accident in 1782. Admiral Kempenfeldt and the whole of the crew of over six hundred men were drowned in this disaster.
To the left of this is a large mortar used at the siege of Namur in 1794, and fired so frequently that the touch hole or vent became fused with the heat. The carriage was burnt away in the fire of 1841, leaving only the framework of iron, which was filled up with wood at a later period.
To the right are French mortars and in the wall is a carved stone panel of the Lion of St. Mark brought from Corfu in 1809.
At the south end of the Mortar Room is the Sub-Crypt of St. John's Chapel, entered through an original doorway. The Sub-Crypt, which has a barrel vault, and is dimly lighted from the east, may have been occasionally used for keeping prisoners, but was normally a store room.
In the west wall is an opening cut in the 18th century, when the basement was used as a powder store. It gives access to THE CANNON ROOM.