42 pounder was the standart heavy casemate gun in the coast fortifications of US Third System until the heavier columbiads of 1850s appeared. Here shown in the parapet mount.
Until the rifled gun, numerically the most important british heavy gun, for navy and fortifications, was the 32 pounder. The first one shown is a Bromfield Pattern gun in the most common casemate garrison carriage, Mk. I, not very different to the mounts of Elizabethan times. With the arrival of Palliser conversions, this and also other SBML old guns had a new life, in some case well after WWI, the second and third guns are examples of this conversions. And the last one is an intresting BL conversion for flank guns, the "caponiere gun", basically a huge shotgun, replaced by machine guns soon before WWI. Cheers.