ight, after which a long wooden sight must be used, graduated for the
whole length of the gun, using the notch in the muzzle.

The bar or stem of the sight has lines across its faces denoting for
all the old guns degrees of elevation, each of which is marked with
the number of yards at which a shot or shell will strike the point
aimed at, when that line is brought to a level with the top of the
sight-box, and the gun is loaded with a specified charge of powder;
for the guns of the new system, the ranges are marked in even hundreds
of yards.

The uppermost line on the stem marked level is the zero of the other
graduations, and when adjusted to the level of the top of the
sight-box, the bottom of the notch in the head of the breech-sight and
the apex of the reinforce-sight show the dispart of the gun. When the
line of sight coincides with these points, it is parallel to the bore,
and when continued to a distant horizon, the gun is laid level or
horizontal.

Sights should invariably be made so that the level line on the stem
will correspond with the bottom of the head when it rests on the
sight-box, and thus secure a dispart-sight in case of accident to the
screw in the sight-box.

A white line, one-fourth (.25) of an inch wide, drawn on top of the
gun from the breech-sight to the notch on the swell of the muzzle, has
been found to greatly facilitate the aim. For night-firing a broad
wooden block, painted dead-white, to ship over the reinforce-sight,
leaving 1/4 of an inch of the sight exposed, will assist in preventing
the aim from being too high.

290. For shot-guns the ranges in yards for one shot with the
distant-firing charge of powder are marked for each degree of
elevation on the right in-board face of the sight-bar; for the
ordinary firing, on the left face.

291. The gun being placed a certain height above the water, depending
on the class of vessel and the deck on which it is mounted, it is
evident that, when the axis of the bore is horizontal, the shot will
have a range proportionate to this height. This range or distance is
commonly called point-blank, or point-blank range, and is the number
noted in the column marked P.B., or 0 deg., or level in range tables.

This point-blank, therefore, depends on the class of gun, the charge,
and the height above the water.

292. A preferable definition of this distance is "range at level."

293. The aim is always supposed to be directed at the water-line. But,