 Northumberland , named after the ceremonial county , was ordered on 2 September 1861 from the Millwall Ironworks . She was laid down on 10 October 1861 at its shipyard in Millwall , London . She was altered while on the building slip after Sir Edward Reed succeeded Isaac Watts as Chief Constructor . Unlike her half @-@ sisters , the ship spent five years on the stocks before she was ready to be launched , partially due to frequent changes in design , although Northumberland was much closer to completion . The additional weight caused her stick for an hour on the slipway before she slid halfway down with her stern only supported by air , threatening to buckle the ship . Efforts by hydraulic jacks and tugboats failed to get her into the water on the next spring tide failed , but the use of pontoons on 17 April 1866 proved successful . Her builders went into bankruptcy while the ship was being launched and the liquidators seized Northumberland as a company asset once she was in the water . Eight months passed before the Admiralty could take possession and begin fitting out the ship . She was commissioned in October 1868 and completed on 8 October for a cost a total of £ 444 @,@ 256 . 
