Revised specification for building Audacious (1869), Invincible (1869), Iron Duke (1870)
A 24 page printed revised specification for building Audacious (1869), Invincible (1869), and subsequently sent to Pembroke Dockyard for Iron Duke (1870), all twin screw iron armour clad frigates (central battery ironclads). The specification contains annotations in red ink and is the basis for the printed, corrected, version ADT0828.