In 1842, experiments were made with iron plates three-eighths of an inch thick, rivetted together to make a total thickness of six inches. It was, however, reported that at 400 yards these were not proof against eight-inch guns or heavy thirty-two pounders. These matters were taken into consideration by Captain Chads, whose official report was as follows:-- “The shot going through the exposed or near side generally makes a clean smooth hole of its own size, which might be readily stopped; and even where it strikes a rib it has much the same effect; but on the opposite side all the mischief occurs; the shot meets with so little resistance that it must inevitably go through the vessel, and should it strike on a rib on the opposite side the effect is terrific, tearing off the iron sheets to a very considerable extent; and even those shot that go clean through the fracture being on the off side, the rough edges are outside the vessel, precluding the possibility almost of stopping them. “As it is most probable that steam vessels will engage directly end-on I have thought it desirable to try to-day what the effect of shot would be on this vessel[83] so placed, and it has been such as might be expected, each shot cutting aways the ribs, and tearing the iron plates away sufficient to sink the vessel in an instant.” [Illustration: THE _LONDON_--TWO DECKER WOODEN CONVERTED SCREW SHIP OF THE LINE. Designed by Sir William Symonds. Launched 1840. Damaged at the bombardment of Fort Constantine, Sevastopol, 1854. Turned into hulk at Zanzibar, 1874.] In 1849 an official report stated that:-- “Shot of every description in passing through iron makes such large holes that the material is improper for the bottom of ships. “Iron and oak of equal weight offering equal resistance to shot, iron for the topsides affords better protection for the men than oak, as the splinters from it are not so destructive. “Iron offering no lodgment for shells in passing through the side, if made with single plates it will be free from the destructive effects that would occur by a shell exploding in a side of timber.” Certain modifications were then introduced and tried in the year 1850, and Captain Chad’s report was that:-- “With high charges the splinters from the shot were as numerous and as severe as before, with the addition in this, and in the former case, of the evils that other vessels are subject to, that of the splinters from the timber. “From these circumstances I am confirmed in the opinion that iron cannot be beneficially employed as a material for the construction of vessels of war.” As a result of this report, seventeen iron ships which were building, the largest being the _Simoon_, of nearly 2,000 tons, were condemned; and it was definitely decided that ships must be built of wood, and that iron in any form was disadvantageous.