The interior of this story is built of crude or sun-dried bricks of small size, laid in bitumen; but it is faced through out with a wall, ten feet in thickness, composed of red kiln dried bricks, likewise cemented with bitumen.

This external wall is at once strengthened and diversified to the eye by a number of shallow buttresses or pilasters in the same material; of these there are nine, including the corner ones, on the longer, and six on the shorter sides.

The width of the buttresses is eight feet, and their projection a little more than a foot.

The walls and buttresses alike slope inwards at an angle of nine degrees.

On the north-eastern side of the building there is a staircase nine feet wide, with sides or balustrades three feet wide, which leads up from the platform to the top of the first story.