and one inch thick, with a brass
notch at the rear end and a point at the other, fixed in, and parallel
to, the upper edge. It is attached, by a stout thumb-screw, to the
axis of the left trunnion, around which it revolves when the screw is
slack.

A semicircular plate, graduated to degrees, is attached to the bar, so
that the sight may be used with the tables showing the corresponding
ranges of the several classes of guns with their distant
firing-charge. (_See_ TABLES OF RANGES, Appendix D.)

The upper edge of the sight-bar corresponds with 0 deg. when the line of
sight is parallel to the axis of the bore. A small level let into the
upper surface of the rear end of the bar shows when the bar is level.

In using this sight, the thumb-screw is first loosened, and the rear
end of the sight raised until the mark on the trunnion coincides with
the degree of elevation required for the range, as given in the
Tables: clamp the thumb-screw, and elevate the gun until the bubble is
at 0 deg., then give the lateral training.

226. Tangent-sights placed on the side of the breech, with a fixed
front sight on the rimbase, as in rifled cannon, will hereafter be
supplied to all pivot-guns; and these will give the sight with equal
accuracy at all elevations.

RAMMERS AND SPONGES.

227. Rammer-heads are to be made of well-seasoned ash, birch, beech,
or other tough wood, of the form and dimensions given in the drawings
furnished by the Bureau to the different Navy Yards. The face of the
rammer is hollowed, so as to embrace the front of the ball and press
the selvagee wad home in its place. A hole is bored lengthwise through
the head to admit the tenon, which is fastened by a pin of hard wood,
three-tenths of an inch in diameter, passing transversely through the
head and tenon. The diameter of the staff is 1.75, and that of the
tenon 1.5 inch. The diameter of the rammer-head will be 0.25 inch less
than that of the bore or chamber to which it is adapted.

For all chambered guns except those of the Dahlgren pattern, the
rammers will be adapted to the chamber, but, as above described, will
answer equally well for the shot and selvagee wad.

Staves are made of tough ash, and are one foot longer than the bores
of the guns for which they are intended: they are to have grooves 1/16
of an inch deep and 1/4 of an inch broad cut in them to show when the
"ordinary charges" are in place, and, by due allowances, the others
also.

For ri