The fissures at the internal flanks of the tower, that, , (ground plan, Fig. 139), looking south, and that, , looking north, are pretty exactly sketched in Figs. 140 and 141.
These fissures slope about 30° from bottom to top towards the east, but they, like the preceding, have been rendered more nearly plumb, by the action of the buttresses and other disturbing causes acting in the interior, which I am unable to examine particularly.
Some roof-tiles have been thrown from the cave at the west end, from (Fig. 140), and are lying at , from 7 to 9 feet horizontally from the base of the wall, having fallen vertically 33 feet.
Taking the horizontal range of projection here, = 9 feet and the vertical descent from the point , = 33 feet, and assuming the velocity of projection to be 13 feet per second (which is about what it proved to be elsewhere in this neighbourhood), and solving for = the
