The two east and two west sides of the octagonal space, which was the prison proper, were longer than the two north and two south sides; the long diameter of the octagon therefore ran across that of the site, extending almost to its north and south limits, while the short diameter stopping short of the boundary by 300 feet, left, east and west, ample room for the barracks of the military garrison and for other buildings. In the very centre of the site, which is also the centre of the prison, was an octagonal block house, mounted with cannon. This is represented in the illustration, a photograph of one of several models made by the prisoners. This model is in the possession of Colonel Strong of Thorpe Hall, by whose grandfather Archdeacon Strong it was bought from its maker at the prison. [Picture: Plate III.—The Block House which stood in the Centre of the Prison] The frontispiece is from a sketch of the centre of the prison, by Captain George Lloyd of the Second West York Militia, taken in 1809. The original is in the collection of the United Service Institution, Whitehall; it shows the accuracy of the model of the block house. In describing the various courts and buildings, it is best to start from the centre, and to trace the arrangement of the parts of the Depot round this point. Symmetrically arranged round this block house, and commanded by its guns, were four quadrangular courts, each strongly fenced by a high stockade fence. The area of each of these courts was about 3½ acres; they were separated from one another by four cross roads, each about twenty feet wide. These roads met in the centre, where the corners of the quadrangular courts were cut off to form the octagonal open space in which stood the block house.