The 100-ton gunwas a 17.72 inch (450 mm) rifled muzzle-loading (RML) gun that was manurfactured by Elswick Ordnance Company, part of Armstrong Whitworth.
In 1874, 12 of these guns were used to arm two Italian battleships, the Dandolo and Duilio. This drove the British to build mount two of these large guns in Malta and two in Gibraltar. Rinella received the gun in 1883 and it was operational by January 1884. These massive RML guns were quickly made redundant by the advent of hte 9.2-ins Breech Loading guns.
The 100 ton gun batteries were;
Malta – Fort Rinella and Fort Cambridge
Gibraltar – Fort Victoria and Fort Napier of Magdala.
Fort Rinella is open to the public and operated by the Fondazzjoni Wirt Artna – the Malta Heritage Trust is a voluntary non-governmental organization (VO/0117). See their web site at http://www.fortrinella.com/.