The Guns On The Parapet Mounted "en barbette". A Barbette Was A Platform, With A Pintle, Behind The Parapet On Which The Guns Were Mounted. A Center Pintle Carriage, Which Both Of These Are, Allows A Full 360 Degree Traverse Of The Gun. The gun closest to the camera is a cast iron 24-pounder Blakely Rifle, P1861, weight 4,700 lbs, with a 4.5-inch bore, 96-inch tube length, firing a 24-lb shell, with a range of 1,901 yards 1,738 metres), mounted on a Center Pintle Carriage.