rrents of iron,
must play a conspicuous part.

Another fact, which will perhaps surprise the general reader, is that
the form and character of _projectiles_ have been matters of as much
difficulty, have received as much investigation, and are of as much
importance, as the shape and character of the guns. In fact, rifled
pieces would be comparatively ineffective except projectiles adapted to
them had been invented. It was necessary that projectiles of greater
weight, of less resistance to the atmosphere, and of more accuracy of
flight, than the old round shot, should be introduced. To accomplish
these ends several things were necessary: 1st, the projectiles should be
elongated; 2d, they should have conical points; 3d, the centre of
gravity should be at a proper distance in front of the centre; 4th,
there should be methods of _steering_ them so that they should always go
point foremost through the whole curve of their flight; 5th, they should
fit the gun so as to take the rifles, yet not so closely as to strain
it. To attain these and other requisites, innumerable plans have been
devised. The projectile offering the best normal conditions is the
_arrow_; it has length, a sharp point, centre of gravity near the head,
and feathers for guiding it (sometimes so arranged that it shall rotate
like a rifled ball). Improved projectiles, therefore, both for muskets
and cannon, correspond in these essentials to the first products of man
in the savage state.

We cannot, in this article, further discuss either such general
principles or those of a more abstruse character, in their application
to artillery, but will briefly state a few facts relative to its
employment--confining ourselves exclusively to the _field service_.

The guns now principally used for battles, in the Northern armies, are
10 and 12-pounder Parrotts, three-inch United States rifles, and light
12-pounder smooth bores. The distinguishing characteristic of the
Parrott guns is lightness of construction, secured by strengthening the
breech (in accordance with the principles mentioned a few paragraphs
back) with a band of wrought iron. This has been applied to guns of all
sizes, and its excellence has been tested by General Gillmore in the
reduction of Forts Pulaski and Sumter. The three-inch guns are made of
wrought iron, are of light weight, but exceedingly tenacious and
accurate. The 12-pounders, sometimes called Napoleons, are of bronze,
with large caliber, and