The report of the Select Committee on Prison Discipline of September 1857 recommended gaol buildings replace the Port Phillip Bay prison hulks. The inquiry recommended adopting London's Pentonvillle design of 1842 to build the gaols. This prison design carried on a revolution begun in 1829 by Eastern State Penitentiary in Philadelphia. The complex was based on a central hall from which radiated wings of cells. The principle of the design being that one guard would stand in the centre of the hall and at one glance survey all cells.