Experiments at Shoeburyness on the Plymouth Breakwater Target: examining the target after firing, 1868. Testing artillery ...on different iron structures designed for land fortifications...One of the targets...represented a compartment of the new iron fort now being erected in Plymouth Sound...The external or front layer is formed of armour-plates 5 in. thick...The wall is...inclined backwards...and the top is further curved over towards the centre, for the purpose of causing shot to glance off...[The] structures...were painted with white lines in squares, to facilitate the aim of the gunners...The gun was then fired by the galvanic battery, after which the effects were observed and recorded...The targets were fired at from the distance of 200 yards. The battery used was composed of five of the most powerful guns that can be procured. Four of these are wrought-iron rifled guns, of Woolwich make...the fifth is an American "Rodman" smooth bore of 19 tons. The Woolwich 23-ton rifled gun has a calibre of 12 in. and throws a projectile of 600 lb. weight...The battering charge is 76lb., which gives a striking velocity, at 200 yards distance, of 1160 ft. per second...The result is considered satisfactory, as only one shell had exploded inside. From "Illustrated London News", 1868.