high, the ball was thrown to a greater distance. Hence the pieces were
charged with two thirds, or even the whole weight of the shot, in order
to impel it with greater velocity; but it has been discovered since,
that the half, or one third of the weight of the ball, is the fittest
charge for the piece[47].
If the whole quantity of powder, employed to charge the cannon, could
take fire at the same instant, it is apparent that the velocity,
communicated to the shot, would increase in proportion to the additional
quantity of powder. But though the time of its inflammation is very
short, it may yet be conceived as divided into many instants. In the
first instant, the powder begins to dilate and impel the shot forward;
and if it has force enough to expel it from the piece before the whole
charge is inflamed, that part which is left to take fire afterwards will
produce no effect at all on the shot. A charge of extraordinary force
does not therefore accelerate the velocity of the bullet: and hence it
follows that the piece ought to be charged with no more powder, than
will take fire whilst the ball is passing through the chace of the
cannon.
It may not be amiss to observe here, that the range of cannon is greater
in the morning and at night, than at noon; and in cold, than in hot
weather. The reason is, that at these times the air being less heated,
gives less way to the dilatation of the powder, which being by this
means confined, as it were, to a smaller sphere of action, must have a
stronger effect in proportion[48].
“When the lengths of cannon are proportional to the height of the
charge, the shot will be discharged with the same velocity, whatever the
calibre may be; and since the ratios of the velocities of shots, issuing
from pieces of different lengths, loaded with different charges of
powder, will be of great use in the construction of cannon, we have
collected them in the following table, where the numbers at the top
express the length of the pieces by the diameter of their shots. That
is, the first is 12 diameters; the second 15, and so on. The first
perpendicular column expresses the charges, in respect to the weight of
the shots: thus, ¼, ⅓, ½, ⅔ imply that the weight of the charge is ¼, ⅓,
½, ⅔ of the weight of the shot. The other numbers, in the same
horizontal lines, express the distance in feet moved over by the
velocities of the shot, uniformly continued in a second of time.
_A Table of Velocities._
│ 12 │ 15 │ 18 │ 21 │ 24 │ 27 │ 30 │ 36 │
─┼────┼────┼────┼────┼────┼────┼────┼────┤
¼│1043│1052│1058│1063│1066│1068│1071│1074│
⅓│1186│1200│1210│1217│1222│1224│1229│1234│
½│1406│1434│1452│1465│1475│1482│1488│1497│
⅔│1568│1613│1641│1662│1677│1688│1698│1711│
“We made use of the diameter of a 9 pound shot, which being 4 inches, is
more convenient in the calculation; and this diameter expresses the
height of the charge when it is a quarter of the weight of the shot, and
the rest in proportion.
“Several remarks may be made upon this table, which are of great
importance in the construction of cannon. First, when the charge is but
a quarter of the shot’s weight, the difference between the velocities,
when the length is 12 and 15 diameters, is but 9 feet in a second; and
the differences between the other velocities decrease as the length
increases.
“Hence, as the difference between the velocities when the piece is 15
and 36 diameters long, is but 22 feet in a second, it is easily
perceived, that when the pieces are charged with one quarter of the
shot’s weight, the length from 12 to 15 diameters is the best.
“Secondly, When the charge is one third of the shot’s weight, the
difference of the velocities, when the piece is 12, 15, and 18 diameters
long, are 14, 10 seconds; and from thence decrease more and more, as the
length of the piece increases: so the length, from 15 to 18 diameters
seems to be the best, every thing being considered.
“Thirdly, and lastly, it appears, from the same manner of reasoning,
that when the charge is one-half of the shot’s weight, the length ought
to be from 18 to 21 diameters; and when the charge is two thirds of the
shot’s weight, the length ought to be from 21 to 24 diameters.”
_Muller’s Artillery._
As one of the effects of the bomb results from its weight, the range of
mortars is extremely different from that of cannon, because the former
is not pointed at a certain object, like the latter, but inclined to the
horizon at a certain angle; so that the bomb, being thrown up obliquely,
much in the same direction as a tennis-ball struck by the racket, may
fall upon the place intended. Hence it appears that the mortar has no
point-blank range, or at least that no use is made of it.
The mortar, being fixed in a situation obliquely with the horizon, so as
that the line _a c_, which passes through the middle of it
longitudinally, being continued, would make an angle _b a d_ with the
horizon _a b_; a bomb, discharged in the direction of this continued
line, would deviate from it every instant of its motion by its weight,
which inclines it downwards, and by this means it would describe a
curve-line, as _a e b_, called a _parabola_[49].
The line _a b_, fig. 19. plate VI. is called the extent of the range, or
the amplitude of the parabola; and the line _a d_, the elevation of the
mortar.
To make a bomb fall on a given place, two things are to be considered;
viz. the elevation of the mortar; and the quantity of powder used to
charge it; both of which may be ascertained as follows: A bomb
discharged from a mortar, pointed vertically, will describe a line
nearly perpendicular to the horizon: I say nearly, because the mortar
will always have some little motion, which will destroy the exact
perpendicularity of the bomb’s flight; but abstracted from this, a bomb,
discharged vertically, would fall again into the mortar[50].
If the mortar be afterwards inclined more and more towards the horizon,
the bomb will fall still farther and farther distant from the mortar,
till the elevation rests at 45°; and the more the mortar is pointed
under this angle, the more will the range of the bomb be diminished: all
of which is strictly demonstrated by geometry. But the following is a
very simple manner of conceiving it, without having recourse to that
science.
A bomb, discharged in the direction of a line, nearly perpendicular to
the horizon, will fall at a little distance from the bomb-vessel. This
requires no proof. A bomb, thrown according to a line that makes a very
acute angle with the horizon, will presently come to the ground by its
weight, and by consequence will not, any more than the other, fall at a
considerable distance from the mortar.
Hence it is easy to conceive, that in order to fall at the greatest
distance from the mortar, the bomb must be fired according to an
elevation at the greatest possible distance, as well from a vertical, as
from an horizontal line. This elevation divides in two equal parts the
angle formed by the vertical and horizontal lines, which being of 90
degrees, or what is called a right angle, a bomb will be thrown to the
greatest distance, in the direction of a line making an angle of 45
degrees. For above this angle the range will diminish, because the bomb
approaches the vertical line; and under the same elevation it will also
decrease, because the flight of the bomb approaches the horizontal line.
Hence also it appears that there are two angles, according to which a
mortar may be inclined to make the bomb fall on the same place; these
are the angles, equally distant from the line, which cuts the quadrant
into two equal parts: so that if, for example, a mortar is elevated at
30°, the bomb will fall at the same distance as if it had been elevated
at 60°, each of these angles being 15° distant on this, and that side of
the quadrant; that is, from the angle of 45 degrees.
The second thing to be considered, is, to know the exact charge of
powder necessary to throw a bomb to a given distance.
If the bomb, being fired at an elevation of 45°, falls short of the
place intended, the charge of powder must be increased. If it reaches
the place, or goes beyond it, it is evident that the charge is
sufficient. If the bomb, at an elevation under 45°, fall short of the
place intended, with a given charge, the mortar must be more elevated:
if, on the contrary, it falls too far off, it must be more inclined to
the horizon: and by these essays the proper degree of inclination may be
easily and speedily discovered.
If the mortar then is raised above 45°, it must be more inclined, so as
to make a more acute angle with the horizon, to increase the range of
the bomb; and, on the contrary, raised nearer a perpendicular, to
diminish it: all of which are consequences drawn from what has been said
on this subject.
It must be observed, first, that the greatest distance to which a bomb
can be thrown, with the strongest charge, is little more than about
1800, or 2000 fathoms.
Secondly, that though a mortar may be elevated indifferently, either so
much above or below 45° as to carry a bomb to a given distance, yet when
any building is to be destroyed, it should be raised above 45°, because
the shell, rising to a greater height when fired according to a greater
angle, falls with greater force, and by consequence will do more damage
to the place on which it is thrown. But when the business is to fire on
a body of men, the mortar must be pointed below 45°, that the bomb may
not have force enough to enter far into the ground, and that the
splinters in the explosion may do more execution.
PRACTICE FOR SEA-MORTARS.
Nature of the Mortar.
13 Inch. 10 Inch. Flight in Ranges in Length of
Powder. Powder. Seconds. Yards. Composition
in Fuses.
lb. oz. lb. oz. Inches Parts
3 0 12 612 2 64
4 0 1 12 14 832 3 8
2 4 15 958 3 30
5 0 2 6 16 1088 3 52
5 8 2 8 17 1299 3 74
3 2 18 1377 2 96
7 0 3 8 19 1534 4 18
4 0 20 1700 4 40
8 12 4 8 21 1874 4 62
9 0 5 8 22 2057 4 84
12 0 23 2248
14 24 2448
16 25 2656
18 8 2 26 2873 5 72
20 0 8 10 27 3098 5 94
22 0 9 8 28 3332 6 16
24 8 11 4 29 3574 6 38
28 0 12 0 30 3821 6 60
31 8 31 4085 6 82
The ranges of mortars, at the several elevations below, are in
proportion to one another, viz.
45 40 35 30 25 20 15 10 5
100 98 94 86 76 64 50 34 17
Example. Knowing the range of a shell at 45 to be 890 yards, required
the range at 30 with the same powder; say, as 100 : 86 : : 890 : 765.4;
and if you have a shell’s range at 30, and would know how far it will go
at 45 with the same quantity of powder, rule as 86 : 100 : : 765.4 :
890.
N. B. These propositions only hold good when the powder is equal.
RATES, the orders or classes into which the ships of war are divided,
according to their force and magnitude.
It has already been observed, in the article NAVY, that this regulation,
which limits the rates of men of war to the smallest number possible,
seems to have been dictated by considerations of political œconomy, or
of that of the simplicity of the service in the royal _dock-yards_. The
British fleet is accordingly distributed into six rates, exclusive of
the inferior vessels that usually attend on naval armaments; as sloops
of war, armed ships, bomb-ketches, fire-ships and cutters, or schooners
commanded by lieutenants.
Ships of the first rate mount 100 cannon, having 42 pounders on the
lower deck, 24 pounders on the middle deck, 12 pounders on the upper
deck, and 6 pounders on the quarter deck and forecastle. They are manned
with 850 men, including their officers, seamen, marines, and servants.
In general, the ships of every rate, besides the captain, have the
master, the boatswain, the gunner, the chaplain, the purser, the
surgeon, and the carpenter; all of whom, except the chaplain, have their
mates or assistants, in which are comprehended the sail-maker, the
master at arms, the armorer, the captain’s clerk, the gunsmith, &c.
The number of other officers are always in proportion to the rate of the
ship. Thus a first rate has six lieutenants, six master’s mates,
twenty-four midshipmen, and five surgeon’s mates, who are considered as
gentlemen; besides the following petty officers: quarter-masters, and
their mates, fourteen; boatswains mates and yeomen, eight; gunners mates
and assistants, six; quarter-gunners, twenty-five; carpenters mates,
two, besides fourteen assistants; with one steward, and steward’s mate
to the purser.
If the dimensions of all ships of the same rate were equal, it would be
the simplest and most perspicuous method to collect them into one point
of view in a table; but as there is no invariable rule for the general
dimensions, it must suffice to remark those of some particular ships in
each rate; for which purpose we have selected some of the latest
construction.
The Victory, which is the last built of our first rates, is 222 feet 6
inches in length, from the head to the stern; the length of her keel,
151 feet 3 inches; that of her gun-deck, or lower deck, 186 feet; her
extreme breadth is 51 feet 10 inches; her depth in the _hold_, 21 feet 6
inches; her burthen 2162 tons; and her poop reaches 6 feet before the
mizen-mast.
Ships of the second rate carry 90 guns upon three decks, of which those
on the lower battery are 32 pounders; those on the middle, 18 pounders;
on the upper-deck, 12 pounders; and those on the quarter-deck, 6
pounders, which usually amount to four or six. Their complement of men
is 750, in which there are six lieutenants, four master’s mates,
twenty-four midshipmen, and four surgeon’s mates, fourteen
quarter-masters and their mates, eight boatswain’s mates and yeomen, six
gunner’s mates and yeomen, with twenty-two quarter-gunners, two
carpenter’s mates, with ten assistants, and one steward and steward’s
mate.
Ships of the third rate carry from 64 to 80 cannon, which are 32, 18,
and 9 pounders. The 80–gun ships however begin to grow out of repute,
and to give way to those of 74, 70, &c. which have only two whole
batteries; whereas the former have three, with 28 guns planted on each,
the cannon of their upper-deck being the same as those on the
quarter-deck and fore-castle of the latter, which are 9 pounders. The
complement in a 74 is 650, and in a 64, 500 men; having, in peace, 4
lieutenants, but in war, 5; and when an admiral is aboard, 6. They have
3 master’s mates, 16 midshipmen, 3 surgeon’s mates, 10 quarter-masters
and their mates, 6 boatswain’s mates and yeomen, 4 gunner’s mates and
yeomen, with 18 quarter-gunners, 1 carpenter’s mate, with 8 assistants,
and 1 steward and steward’s mate under the purser.
Ships of the fourth rate mount from 60 to 50 guns, upon two decks, and
the quarter-deck. The lower tier is composed of 24 pounders, the upper
tier of 12 pounders, and the cannon on the quarter-deck and fore-castle
are 6 pounders. The complement of a 50 gun ship is 350 men, in which
there are three lieutenants, 2 master’s mates, 10 midshipmen, 2
surgeon’s mates, 8 quarter-masters and their mates, 4 boatswain’s mates
and yeomen, 1 gunner’s mate and 1 yeoman, with 12 quarter-gunners, 1
carpenter’s mate and 6 assistants, and a steward and steward’s mate.
All vessels of war, under the fourth rate, are usually comprehended
under the general name of frigates, and never appear in the line of
battle. They are divided into the 5th and 6th rates, the former mounting
from 40 to 32 guns, and the latter from 28 to 20. The largest of the
fifth rate have two decks of cannon, the lower battery being of 18
pounders, and that of the upper-deck of 9 pounders; but those of 36 and
32 guns have only one complete deck of guns, mounting 12 pounders,
besides the quarter-deck and fore-castle, which carry 6 pounders. The
complement of a ship of 44 guns, is 280 men and that of a frigate of 36
guns, 240 men. The first has 3, and the second 2 lieutenants; and both
have 2 master’s mates, 6 midshipmen, 2 surgeon’s mates, 6
quarter-masters and their mates, 2 boatswain’s mates and 1 yeoman, 1
gunner’s mate and 1 yeoman, with 10 or 11 quarter-gunners, and 1
purser’s steward.
Frigates of the 6th rate carry 9 pounders, those of 28 guns having 3
pounders on their quarter-deck, with 200 men for their complement; and
those of 24, 160 men; the former has 2 lieutenants, the latter, 1; and
both have 2 master’s mates, 4 midshipmen, 1 surgeon’s mate, 4
quarter-masters and their mates, 1 boatswain’s mate and 1 yeoman, 1
gunner’s mate and 1 yeoman, with 6 or 7 quarter-gunners, and 1 purser’s
steward.
The sloops of war carry from 18 to 8 cannon, the largest of which have 6
pounders; and the smallest, viz. those of 8 and 10 guns, 4 pounders.
Their officers are generally the same as in the 6th rates, with little
variation; and their complements of men are from 120 to 60, in
proportion to their force or magnitude.
N. B. Bomb-vessels are on the same establishment as sloops; but
fire-ships and hospital-ships are on that of fifth rates.
Having already exhibited the dimensions of the largest first rate in our
navy, we have, in the following table, collected those of the inferior
rates:
│Guns.│ Length of│ Length of │ Extreme │ Depth in │Bur- │
Rates. │ │ the keel. │ the lower │ breadth. │ the hold. │then │
│ │ │ deck. │ │ │ in │
│ │ │ │ │ │tons.│
│ │Feet. Inch.│Feet. Inch.│Feet. Inch.│Feet. Inch.│ │
2d rate, │ 90│ 144 ¾│ 177 6 │ 50 │ 21 │ 1934│
Barfleur, │ │ │ │ │ │ │
│ │ │ │ │ │ │
3d Arro- │ 74│ 138 │ 168 3 │ 47 4 │ 19 9│ 1644│
rate, gant, │ │ │ │ │ │ │
Europa,│ 64│ 139 │ 159 │ 44 4 │ 19 4│ 1366│
│ │ │ │ │ │ │
4th rate, │ 50│ 120 8 │ 146 │ 40 4 │ 17 4│ 1044│
Salisbury, │ │ │ │ │ │ │
│ │ │ │ │ │ │
5th Phœnix,│ 44│ 116 11 │ 140 9 │ 37 1⅜│ 16 │ 856│
rate, │ │ │ │ │ │ │
Venus, │ 36│ 106 3 │ 128 4½│ 35 9 │ 12 4│ 722│
│ │ │ │ │ │ │
6th Carys- │ 28│ 97 3½│ 118 4 │ 33 8 │ 10 6│ 586│
rate, fort, │ │ │ │ │ │ │
Dol- │ 24│ 93 4 │ 113 │ 32 1 │ 11 │ 511│
phin, │ │ │ │ │ │ │
│ │ │ │ │ │ │
Sloop, │ 16│ 80 7⅝│ 98 │ 27 2 │ 12 8│ 316│
Nautilus, │ │ │ │ │ │ │
Nothing more evidently manifests the great improvement of the marine
art, and the degree of perfection to which it has arrived in England,
than the facility of managing our first rates; which were formerly
esteemed incapable of government, unless in the most favourable weather
of the summer. In testimony of this observation we may, with great
propriety, produce the example of the Royal George, which, during the
whole course of the late war, was known to be as easily navigated, and
as capable of service, as any of the inferior ships of the _line_, and
that frequently in the most tempestuous seasons of the year. The
ingenious M. Du Hamel, who is eminently distinguished for his knowledge
of marine affairs, has indeed judiciously objected to the defects and
bad qualities of such large ships[51]. It is nevertheless hardly
possible for any Englishman, who was witness to the defeat of M.
Conflans, by the victorious Sir Edward Hawke, on the ever-memorable 20th
of November, without dissenting a while from that gentleman’s opinion.
In reality, a fact, confirmed by repeated experience, must unavoidably
triumph over all theoretical conclusions.
Ships of the second rate, and those of the third, which have three
decks, carry their sails remarkably well, and labour very little at sea.
They are excellent in a general action, or in cannonading a fortress.
Those of the third rate, which have two tiers, are fit for the line of
battle, to lead the convoys and squadrons of ships of war in action, and
in general, to suit the different exigencies of the naval service.
The fourth rates may be employed on the same occasions as the third
rates, and may be also destined amongst the foreign colonies, or on
expeditions of great distance; since these vessels are usually excellent
for keeping and sustaining the sea.
Vessels of the fifth rate are too weak to suffer the shock of a line of
battle; but they may be destined to lead the convoys of merchant-ships,
to protect the commerce in the colonies, to cruize in different
stations, to accompany squadrons, or be sent express with necessary
intelligence and orders. The same may be observed of the sixth rates.
The frigates, which mount from 28 to 38 guns upon one deck, with the
quarter-deck, are extremely proper for cruizing against privateers, or
for short expeditions, being light, long, and usually excellent sailers.
RATTLINGS, _enflechures_, certain small lines which traverse the
_shrouds_ of a ship horizontally, at regular distances from the deck,
upwards, and forming a variety of ladders, whereby to climb to any of
the mast-heads, or descend from them. Hence the term is apparently
derived from _rath_, an obsolete word, signifying an hill.
In order to prevent the rattling from slipping down by the weight of the
sailors, they are firmly attached by a knot, called a _clove-hitch_, to
all the shrouds, except the foremost or aftmost; where one of the ends,
being fitted with an eye-splice, is previously fastened with twine or
packthread.
REACH, (_ræcan_, Sax.) the line, or distance, comprehended between any
two points or stations on the banks of a river, wherein the current
flows in a streight uninterrupted course.
REAR, (_arriere_, Fr.) a name given to the last division of a squadron,
or the last squadron of a fleet, and which is accordingly commanded by
the third officer of the said fleet or squadron. See the article
DIVISION.
REEF, _ris_, (_reef_, Dutch) a certain portion of a sail, comprehended
between the top or bottom, and a row of eyelet-holes parallel thereto.
The intention of the reef is to reduce the surface of the sail in
proportion to the increase of the wind; for which reason there are
several reefs parallel to each other in the superior sails, whereby they
may be still farther diminished, in order to correspond with the several
degrees of the gale. Thus the top-sails of ships are usually furnished
with three reefs, _l_ _m_ _n_, fig. 1. plate IX. parallel to the yard;
and there are always three or four reefs, parallel to the bottom on
those main-sails and fore-sails, which are extended upon booms: a
circumstance common to many of the small vessels.
REEF also implies a chain of rocks, lying near the surface of the water.
REEF-BAND, a piece of canvas, sewed across the sail, to strengthen it in
the place where the eyelet-holes of the reefs are formed.
REEFING, the operation of reducing a sail, by taking in one or more of
the reefs, which is either performed by lines, _points_, or _knittles_.
Thus the top-sails are always, and the courses generally, reefed with
points, which are flat braided pieces of cordage, whose lengths are
nearly double the circumference of the yard. These being inserted in the
eyelet-holes, are fixed in the sail by means of two knots in the middle,
one of which is before, and the other behind the reef-band.
In order to reef the top-sails with more facility and expedition, they
are lowered down and made to _shiver_ in the wind, which considerably
relaxes their tension. The extremities of the reef are then drawn up to
the _yard-arms_ by an assemblage of pullies communicating with the deck,
termed the _reef-tackle_; and they are securely fastened to the
yard-arms by small cords, called _earings_. The space of sail,
comprehended in the reef, is then laid smoothly over the yard, in
several folds, or doubles: and the whole is completed by tying the
points about the yard, so as to bind the reef close up to it.
The courses of large ships are either reefed with points or small cords,
which are thence called _reef-lines_. In the latter case the line is
passed spirally through the eyelet-holes of the reef, and over the head
of the sail alternately, and afterwards strained as tight as possible.
It must be observed, however, that the reef-line is sometimes passed
round the yard, and sometimes only round the head of the sail; and each
of these methods have their advocates, with arguments more or less
convincing. But if it should appear essential to prevent the friction by
which a sail is galled between the line and the yard; and as the
rope-bands are sufficient to sustain the effort of the sail, it is
certainly much better to pass the line only round the sail, provided
that the turns are inserted through the _roband-legs_; a circumstance
which is carefully practised by every skilful sailor.