The most interesting portion of the gun department is the factory devoted to the construction of Lancaster shells. This odd-looking missile has a form very similar to a champagne bottle, and, unlike the ordinary shell, is made out of a single sheet of wrought iron. The slab of metal having been welded into a cylindrical form, is submitted to an ingenious lathe, which, acting upon it simultaneously with a dozen different tools inside and out, speedily reduces it to a given weight and a perfectly uniform thickness. The cylinder, about eighteen inches in length and ten in diameter, is then made red hot, and whilst in this state is placed in the grip of a powerful machine, which by a series of blows, equally distributed over every part, converts it into the likeness of a French bottle in less than five minutes, without the slightest sign of crumpling in any portion of the surface. The operation can only be compared to the manner in which a potter shapes a vessel upon the wheel. No less than forty machines are employed on this special manufacture, and upwards of a hundred shells can be turned out daily. The expense incurred in producing with extreme accuracy and speed these curious missiles for the first rifled gun adopted by the service, is an earnest of the determination of the authorities to carry the manufacture of artillery to the same perfection of finish as their small arms. Lancaster guns will in all probability play a very important part in the next war, if war there should ever unhappily be, as those in use in the Crimea made most splendid practice, firing with nearly the accuracy of a rifle, and attaining a range of 5,000 yards, or very nearly three miles. As these shells cost about 25_s._ each, the expense of "passing the bottle" to the enemy is rather a serious affair.