1st. Allow the Gun Captain to estimate the distance to windward or to
leeward, right or left, to be allowed for the deflection; or,

2d. Indicate the number of yards right or left of the object; which,
after all, depends on his estimation of distance.

3d. Furnish a sight which, in addition to the elevation, allows for
the deviation, and permits the Gun Captain in all cases to aim
directly at the target.

Such a sight is furnished to the Parrott rifles, and is desirable for
all guns.

304. In case the ordinary sights should be lost or rendered useless,
tangent firing may be resorted to against ships, by pointing with the
wooden dispart-sight at such part of the ship as the Tables indicate
for the distance, and according to the class of gun in use at the
time.

A Table of this kind is appended, which has been calculated for the
8-inch and some of the heavier of the 32-pounder guns when loaded with
single shot and distant-firing charges.

The different classes of sailing ships-of-war, whether of the same or
of different nations, are not of the same length, nor are their masts
of the same height from the deck, or from the water. They, however,
correspond so nearly, for the same class of ships of the same nation,
that calculations made from the angles subtended by the average height
of their masts, will generally give their distance with sufficient
accuracy for general firing.

Tables are inserted at the end of the book, in which the distances
corresponding to different angles made by the masts of English and
French ships-of-war are shown--from which the intermediate distances
due to other angles may be estimated, and the sights regulated
accordingly, if circumstances should render it desirable. Also an
abridged Table, in which the height of our own mast is used as the
base.

305. Officers of divisions and Captains of guns should be occasionally
practised in measuring the distances of objects by the eye, at times
when opportunities offer of verifying the accuracy of their estimate
by comparing it with the distance obtained by the foregoing methods,
or any other which will afford the best means of comparison.

306. Within point-blank range, if the hull of an enemy's vessel is
obscured by smoke or darkness, the aim may be directed by the flashes
of his guns.

307. Most naval guns are now fitted with elevating screws, passing
through a hole in the cascabel of the Dahlgren system, and for those
of the old system