Large Round Shot Against Iron

Clad Smrs. - The Ordnance Department and the public are vory auxious to test Rodman 15 i:icb gun by actual experiment. It is not doubted that the Union gun and the Floyd gun, at Fortress Monroo will smash in thu sidea of any Buip or battery thut the rebels inay have loaded down with armor up to the liinits of flotation. Here is afact lor them : - Upwards of five years ago, the Mersey Steel and Iron Coinpany firod a 282 ]b. shot with 5 Ibs of powder, at 120 yards range, froni thcir 13 inch gun, at a píate made for one of the English iron-c'ad hips, by the Messrs. Horsfall. The plato was 3 feet 9 inche, by 2 fet Ö inches, by 4 3 8 inches thick, and weigheci 17 cwt. plato was placed against tho ends of nino bulks of timber, 6 feet long by lunches square, secured together by cross plank and beddcd in saud. - The ball struck a little to the left of the centor, aud drovo the portion against which it truck, a distance of 3((0 yards, ghattoring the ffhole plato, and arivÏDg the timbers to somc diátance. The shot was also shattered. After this report, which is official, we need stand in no fear of nny mailed fleets yct afloat, if we can gei a hat at them with our 15-inch guus, of whicli the balls weigh -125 Ibs., and are driveu by 40 Ibs. of powder. The ghot of a 20-inch gun, which is doerued uraetieable by lioilinan's process of inr wmild wciïli lialf a