Lancaster’s oval shell, oscillated in its flight, took a flight so extraordinary, on account of the resistance of the atmosphere on the protuberances of the oval, that the principle may be regarded as fully established that enlarged projectiles must be smooth and free from projections that “saw the air,” otherwise range and accuracy of fire will be sacrificed. The principle of Mr. Whitworth’s polygonal bore is fully discussed in its proper place, and will here receive only a passing notice.
To Mr. W. G. Armstrong, of Newcastle-upon-Tyne, much more credit is due than can be claimed for Mr. Whitworth. Long before the paid efforts of Mr. Whitworth, Mr. Armstrong had made the subject of rifled cannon a special study, and the success of his investigations has been such as to couple his name with those of the earliest inventors of effectual rifled cannon. Mr. Armstrong may also lay claim to being an originator of wrought steel cannon; though here his name stands second as an inventor, for to Mr. Krupp is due the honour of first introducing cast steel cannon to the notice of our Government.
Mr. Armstrong tells his own tale so well in the columns of the _Times_ that we cannot do better than quote it:--
“In the latter part of 1854, I submitted to the Duke of Newcastle, then Minister at War, a proposal for a gun which I anticipated would possess great superiority over the common forms of light artillery, and I undertook, with his Grace’s authority, to construct a field-piece in conformity with the plan I had suggested. The gun was accordingly soon afterwards made, and has since, during a period of nearly two years, been the subject of numerous experiments, partly upon the ordnance firing-ground at Shoeburyness; but principally under my own direction in this neighbourhood.
“I have hitherto avoided publicity in reference to these experiments, but, as matured results of much interest and importance have now been arrived at, and as other names are already before the public in connection with gun experiments made during the same period, I feel that I may now, without impropriety, give some information on the subject.
“With a view to strength and durability, the gun is composed internally of steel and externally of wrought iron, applied in a twisted or spiral form, as in a musket or fowling-piece. The bore is nearly two inches in diameter, and is rifled. The projectile is a pointed cylinder 6-1/2 inches long, and its weight is 5 lb. It is made of cast iron, coated with lead, and is fired from the gun with a charge of 10 ounces of powder; it contains a small cavity in the centre, and may be used either as a shot or a shell. When applied as a shell, the cavity is filled with powder, and a detonating fuse is inserted in front, so as to fire the powder in the centre on striking an object. When used as a shot, the powder is omitted, and an iron point, which favours penetration, is substituted for the fuse. The gun is constructed to load at the breech, the object being not only to obviate the disadvantages of sponging and loading from the front, but also to allow the projectile to be larger in diameter than would enter at the muzzle, and thus to insure its taking the impress of the grooves and completely filling the bore. The piece weighs 5 cwt., and is mounted upon a carriage which bears a general resemblance to that of an ordinary 6-pounder field gun, but which embraces a pivot frame and recoil slide. A screw is also applied, not only for elevating and depressing the gun, but also for moving it horizontally, by which means great delicacy of aim is effected. The recoil slide has an upward inclination, which enables the gun, after running back, to recover its position by gravity; and its use is to relieve the pivot-frame and adjusting screws from injurious concussion.