The Secretary of State may from time to time by any general or special rule appoint in any county or burgh a convenient prison or prisons in which prisoners are to be confined before and during trial, or at either of such times, and any prisoner who might, if this Act had not passed, have been lawfully confined in a prison situate within the area of such county or burgh may be lawfully confined in any prison or prisons so appointed : Moreover, the Secretary of State may by any general or special rule from time to time appoint any convenient prison or prisons in any adjoining or adjacent county or burgh to which prisoners may be committed for trial, safe custody, punishment, or otherwise, and any prisoners may be committed to such prison accordingly.