surface of its bore, for the purpose of giving the projectile a motion
about a line coinciding with the direction of its flight. See ORDNANCE,
SMALL-ARMS, MAGAZINE GUNS, and LYMAN’S MULTI-CHARGE GUN.
=Rifle Projectile.= See PROJECTILE.
=Rifled Cannon=, or =Rifle-cannon=. A cannon of which the bore is
rifled.
=Rifled Musket.= A musket of which the bore is rifled.
=Riflemen.= A peculiar kind of light infantry, consisting of experienced
marksmen, armed with the most improved rifles. In the British army there
are two battalions of the rifle brigade and of the 60th Rifles, the
Ceylon Rifles, and the Cape Mounted Riflemen.
=Rifle-pit.= A pit dug for the shelter of sharpshooters.
=Rifling.= The yielding nature of lead renders the application of the
rifle principle of easy accomplishment in the case of rifle-muskets, but
such is not the case with rifle-cannon where the projectiles are made of
iron. The object of the most recent experiments is to determine the
safest and surest means of causing the projectile to follow the spiral
grooves as it passes along the bore of a rifled piece. For description
of the manner of doing this, see PROJECTILE.
_Form of Groove._--The form of a rifle groove is determined by the angle
which the tangent at any point makes with the corresponding element of
the bore. If the angles be equal at all points the groove is uniform.
If they increase from the breech to the muzzle, the grooves are called
increasing; if the reverse, decreasing. The inclination of a rifle
groove at any point is measured, accurately, by the tangent of the angle
which it makes with the axis of the bore, which is always equal to the
circumference of the bore divided by the length of a single revolution
of the spiral, measured in the direction of the axis. Grooves are of two
kinds,--_uniform_ and _variable_.
_Uniform Groove._--The comparative advantages of uniform and variable
grooves depend on the means used to connect them with the projectiles.
If the bearing of the projectile in the grooves be long, and the metal
of which it is made be unyielding, it will be unsafe, if not
impracticable, to employ variable grooves, and if the metal be partially
yielding, a portion of the force of the charge will be expended in
changing the form of that part of the projectile which projects into the
grooves, as it moves along the bore.
_Variable Groove._--The variable groove may be used to advantage when
the portion of the projectile in the grooves is so short that its form
will undergo but slight alteration; the variable groove diminishes the
friction of the projectile when it is first set in motion, and thereby
relieves the breech of the piece of a portion of the enormous strain
which is thrown upon it. If the twist be too rapid towards the muzzle
there will be danger of bursting the piece in the chase.
_Width of Groove._--The width of a groove depends on the diameter of the
bore and the peculiar manner in which the groove receives and holds the
projectile. Wide and shallow grooves are more easily filled by the
expanding portion of the projectile than those which are narrow and
deep; and the same holds true of circular-shaped grooves when compared
to those of angular form.
_Number of Grooves._--An increase in the number of grooves increases the
firmness with which a projectile is held, by adding to the number of
points which bear upon it. A large number of grooves, however, increase
the difficulties of loading. For expanding projectiles an odd number of
grooves is generally employed, for as this places a groove opposite to a
land, less expansion will be required to fill them.
_Inclination of Grooves._--Experience has shown that, as the velocity of
rotation depends upon the form and initial velocity of the projectile,
the causes which retard it, and the time of flight, there is a
particular inclination of grooves which is best suited to each caliber,
form of projectile, charge of powder, and angle of fire. The farther the
centre of gravity of a projectile is in rear of the centre of figure, or
resistance of the air, the greater must be the inclination of the
grooves to resist deviation. It therefore follows that a conical
projectile of the same length and diameter, requires a greater
inclination of grooves than a cylindrical projectile, and the same will
hold true for other forms as they approach one or the other of these
extreme cases. The friction of the projectile as it passes along the
grooves, increases with their inclination; its effect will be to
diminish the range and increase the strain on the piece, and the
inclination may be carried so far as to break the projectile, or rupture
the piece.
_Centring._--In consequence of the windage necessary in all
muzzle-loading guns, the axis of the projectile does not always coincide
with that of the bore in firing. This leads to inaccuracy of fire. A
projectile is said to be centred when the grooves of the rifling are so
constructed as to bring the axis of the projectile on a line with that
of the bore when the piece is fired. There are several ways of
accomplishing this, among them Armstrong’s method called “Shunt
rifling.” See ARMSTRONG GUN under ORDNANCE, CONSTRUCTION OF, the KRUPP,
and others.
=Riga.= An important seaport of Russia, capital of Livonia, on the Düna,
312 miles southwest from St. Petersburg. Riga was founded in the
beginning of the 13th century. The Teutonic Knights possessed it in the
16th century. In 1621 it was taken by Gustavus Adolphus, and in 1710,
after a vigorous resistance, by Peter the Great. On the latter occasion
more than half of the town was destroyed. In 1812 a French force was
repulsed from the town.
=Rigodon= (_Fr._). Formerly a beat of drum while men who were shelled (a
French punishment, the severest next to death) were paraded up and down
the ranks previous to their being sent to their destination.
=Rimbases.= In gunnery, are short cylinders uniting the trunnions with
the body of the gun. The ends of the rimbases, or the _shoulders_ of the
trunnions, are planes perpendicular to the axis of the trunnions.
Rimbases are for the purpose of strengthening the trunnions at their
junction with the piece, and by forming shoulders, to prevent the piece
from moving sideways in the trunnion-beds.
=Rimer.= A palisade in fortification.
=Rimini= (anc. _Ariminum_). A city of Central Italy, on the Adriatic
Sea, about 28 miles east-southeast from Forli. It was founded by the
Umbri; was conquered by the Romans; sacked by Sulla; plundered and
destroyed several times by the barbarians; then given by Charlemagne to
the church.
=Rimnik.= A town of Wallachia, on the Rimnik, 66 miles northeast from
Bucharest. Here the Austrians and Russians, under Prince Coburg and Gen.
Suwarrow, gained a great victory over the Turks, September 22, 1789.
=Ring-armor.= Armor composed of rings of metal.
=Ringleader.= The leader of a ring; especially, the leader of an
association of men engaged in violation of law or an illegal enterprise,
as rioters, mutineers, and the like.
=Ring-mail.= A kind of mail composed of small rings of steel sewed
edgewise upon a strong garment of leather or of quilted cloth.
=Ring-wads.= See GROMMET.
=Rio Janeiro=, or =Rio de Janeiro=, often called simply Rio. The capital
of Brazil, and the largest and most important city of South America. The
harbor, which is strongly fortified, is one of the best in the world,
and large enough for all its navies. The city of Rio was founded by the
Portuguese in 1567. In 1831, it was the theatre of a revolution, in
which 6000 armed citizens were joined by the troops of the line in their
opposition to the government, and in consequence of which Dom Pedro
abdicated the throne in favor of his son Pedro II.
=Riot and Tumult.= Sedition, civil insurrection, disturbance, etc. A
breach of the peace committed by an assembled multitude. Some degree of
violence is incidental to a riot, and a degree of intimidation to the
neighborhood. According to law a riot cannot take place unless three
persons act in concert. When a riot becomes formidable, it is usual for
the authorities to take active measures to disperse it.
=Rioters.= Disturbers of the public peace; persons acting in open
violation of good order; raising or creating sedition, etc.
=Ripon.= An ancient town of England, in Yorkshire, 23 miles northwest of
York. It suffered much by the ravages of the Danes and the Normans
(1069), and the Scots (1319 and 1323).
=Risban= (_Fr._). In fortification, a flat piece of ground upon which a
fort is constructed for the defense and security of a port or harbor. It
likewise means the fort itself.
=Risberme= (_Fr._). A work composed of fascines, such as is sometimes
constructed at the bottom of a town-wall. A sort of glacis of
fascine-work used in jetties, the sides of which, towards the sea, are
so formed as to withstand its violence.
=Rise.= In a military sense, is to make hostile attack; as, the soldiers
rose against their officers. It also means to obtain promotion. _To rise
from the ranks_, is to obtain a commission by degrees, after having been
in the ranks as a private soldier.
=Rising.= In heraldry, a term applied to a bird when represented opening
his wings as if about to take flight.
=Riveting-plates.= In gun-carriages, are small, square, thin pieces of
iron, through which the ends of the bolts pass, and are riveted upon
them.
=Rivoli.= A town of Italy on the right of the river Dora, and 8 miles
west of Turin. It possesses a royal castle, which was sacked by the
French in 1690. In 1797 a battle was fought here between the French and
Austrians, in which the former were victorious.
=Rizamedar.= In the East Indies, is an officer commanding a small body
of horse.
=Roanoke.= A river of Virginia and North Carolina; empties into
Albemarle Sound. In 1861, Albemarle Island, at its mouth, and Plymouth
were taken by the Federal gunboats.
=Robinet.= An ancient military machine for throwing darts and stones.
=Rochelle, La.= A fortified seaport of France, capital of the department
of Charente-Inférieure, on an inlet of the Bay of Biscay, 300 miles
southwest of Paris by railway. It was taken from the English by the
troops of the French king Louis XIII. in 1224; was ceded to England at
the treaty of Bretigny in 1360; in the subsequent wars it was retaken by
France, under whose sway it has remained since 1372. As a stronghold of
the Huguenot party, it underwent various attacks and sieges during the
religious wars of the Henries, in the latter half of the 16th century;
and on its final and unconditional surrender to the royal troops in the
time of Louis XIII., its old fortifications were destroyed, and new
lines of defenses subsequently erected by the great Vauban.
=Rock Island.= An island in the Mississippi River, the southern
extremity of which is nearly opposite the town of Rock Island, Ill. This
island is about 3 miles in length, and presents a perpendicular front of
limestone 20 or 30 feet high. During the Blackhawk war a garrison was
kept on Rock Island, and a part of it was used during the late civil war
(1861-65) as a military prison. The U. S. government has a splendid
arsenal and armory here.
=Rocket.= A rocket is a projectile which is set in motion by a force
residing within itself; it therefore performs the twofold function of
piece and projectile. See PYROTECHNY.
_History._--Rockets were used in India and China for war purposes before
the discovery of gunpowder; some writers fix the date of their invention
about the close of the 9th century. Their inferior force and accuracy
limited the sphere of their operations to incendiary purposes, until the
year 1804, when Sir William Congreve turned his attention to their
improvement. This officer substituted sheet-iron cases for those made of
paper, which enabled him to use a more powerful composition; he made the
guide-stick shorter and lighter, and removed a source of inaccuracy of
flight by attaching the stick to the centre of the base instead of the
side of the case. The advantages claimed for rockets over cannon are,
unlimited size of projectile, portability, freedom from recoil, rapidity
of discharge, and the terror which their noise and fiery trail produce
on mounted troops.
_Structure._--A rocket is essentially composed of a strong case of paper
or wrought iron, inclosing a composition of nitre, charcoal, and
sulphur,--the same as gunpowder, except that the ingredients are
proportioned for a slower rate of combustion. If penetration and range
be required, its head is surmounted by a solid shot; if explosion and
incendiary effect, by a shell or spherical case-shot, to which is
attached a fuze, which is set on fire when it is reached by the flame
of the burning composition. The base is perforated by one or more vents
for the escape of the gas generated within, and sometimes with a
screw-hole to which a guide-stick is fastened.
_Motion._--A rocket is set in motion by the reaction of a rapid stream
of gas escaping through its vents. If it be surrounded by a resisting
medium, the atmosphere, for instance, the particles of gas as they issue
from the vent will impinge against and set in motion certain particles
of air, and the force expended on the inertia of these particles will
react and increase the propelling force of the rocket. It follows,
therefore, that, though a rocket will move _in vacuo_, its propelling
force will be increased by the presence of a resisting medium. Whether
the effect will be to accelerate the rocket depends upon the relation
between the resistance which the medium offers to the motion of the gas
and that which it offers to the motion of the rocket.
_Vent._--As the rate of combustion of the composition is independent of
the pressure of the gas in the bore, it follows, that if the size of the
vent be contracted, the flow of gas through it will be accelerated. The
strength of the case, and the friction of the gas, which increases as
the vent diminishes, alone limit the reduction of the size of the vent.
For vents of the same size, but of different shapes, that one which
allows the gas to escape most freely will be most favorable to the
flight of the rocket. A conical form of vent, with the larger orifice
next to the bore, will allow the gas to escape more rapidly than one of
cylindrical form.
_Bore._--As the composition of a rocket burns in parallel layers of
uniform thickness, the amount of gas generated in a given time, or the
velocity of its exit from the case, depends on the extent of the
inflamed surface. Experience shows that to obtain the required surface
of inflammation, it is necessary to form a long cavity in the mass of
the composition. This cavity is called the bore. In all rockets the bore
should be concentric with the case; its shape should be made conical to
diminish the strain on the case near its head, by reducing the amount of
surface where the pressure on the unit of surface is greatest.
_Nature of Movement._--Suppose the rocket in a state of rest, and the
composition ignited; the flame immediately spreads over the surface of
the bore, forming gas which issues from the vent. The escape is slow in
the first moments, as the density of the gas is slight; but as the
surface of inflammation is large compared to the size of the vent, the
gas accumulates rapidly, and its density is increased until the velocity
of the escape is sufficient to overcome the resistance which the rocket
offers to motion. These resistances are, inertia, friction, the
component of weight in the direction of motion, and, after motion takes
place, the resistance of the air. The constant pressure on the head of
the bore accelerates the motion of the rocket until the resistance of
the air equals the propelling force; after this, it will remain constant
until the burning surface is sensibly diminished. When the gas ceases to
flow, the rocket loses its distinctive character, and becomes, so far as
its movement is concerned, an ordinary projectile. The increase in the
surface of combustion whereby more gas is developed in the same time,
and the diminution in the weight of the remaining composition, cause the
point of maximum velocity to be reached with increased rapidity. If the
weight of the rocket be increased, the instant of maximum velocity will
be prolonged, but the amount will remain the same. A change in the form
of the rocket which increases the resistance of the air, will have the
effect to diminish the maximum velocity.
_Guiding Principle._--The propelling force of a rocket changes its
direction with the axis along which it acts; it follows, therefore, that
without some means of giving stability to this axis, the path described
will be very irregular, so much so, at times, as to fold upon itself;
and instances have been known where these projectiles have returned to
the point whence they started. The two means now used to give steadiness
to the flight of a rocket are, rotation, as in the case of a rifle-ball,
and the resistance of the air, as in an arrow.
_Hale’s System._--The first is exemplified in Hale’s rocket, where
rotation is produced around the long axis by the escape of the gas
through five small vents situated obliquely to it. In his first
arrangement, the inventor placed the small vents in the base,
surrounding the central vent, so that the resultant of the tangential
forces acted around the posterior extremity of the axis of rotation. In
1855, this arrangement was changed by reducing the number of the small
vents to three, and placing them at the base of the head of the rocket.
The rocket thus modified is the one now used by the U. S. government for
war purposes. A still later improvement in Hale’s rocket consists in
screwing a cast-iron piece into the bottom of the case, which is
perforated with three vents. A corresponding side of each vent is
surrounded with a fence, the opposite sides being open. The gas in its
efforts to expand after issuing from the vents, presses against the
fences and rotates the rocket around its long axis.
_Congreve’s System._--A Congreve rocket is guided by a long wooden stick
attached to its base. If any cause act to turn it from its proper
direction, it will be opposed by resistances equal to its moment of
inertia and the lateral action of the air against the stick. The effect
of these resistances will be increased by placing the centre of gravity
near the head of the rocket, and by increasing the surface of the stick.
In signal-rockets, where the case is made of paper, the stick is
attached to the side, and there is but one large vent, which is in the
centre of the case. In war-rockets the stick is attached to the centre
of the base, and the large central vent is replaced by several small
ones near its circumference. The former arrangement is not so favorable
to accuracy as the latter, inasmuch as rotation will be produced if the
force of propulsion and the resistance of the air do not act in the same
line.
_How Fired._--Rockets are generally fired from tubes or gutters; but
should occasion require it, they may be fired directly from the ground,
care being taken to raise the forward end by propping it up with a stick
or stone. As the motion is slow in the first moments of its flight, it
is more liable to be deviated from its proper direction at this time
than any other; for this reason the conducting-tube should be as long as
practicable.
_Form of Trajectory._--Take that portion of the trajectory where the
velocity is uniform. The weight of the rocket applied at its centre of
gravity, and acting in a vertical direction, and the propelling force
acting in the direction of its length, are two forces the oblique
resultant of which moves the rocket parallel to itself; but the
resistance of the air is oblique to this direction, and acting at the
centre of figure, a point situated between the centre of gravity and
extremity of the guide-stick, produces a rotation which raises the
stick, and thereby changes the direction in which the gas acts. As these
forces are constantly acting, it follows that each element of the
trajectory has less inclination to the horizon than the element of an
ordinary trajectory in which the velocity is equal. When the velocity is
not _uniform_, the position of the centre of gravity has a certain
influence on the form of the trajectory. To understand this, it is
necessary to consider that the component of the resistance of the air
which acts on the head of the rocket is greater than that which acts on
the side of the stick. It is also necessary to consider that the
pressure of the inflamed gas acts in a direction opposite to the
resistance of the air, that is to say, from the rear to the front, and
that the centre of gravity is near the rear extremity of the case. At
the beginning of the trajectory, when the motion of the rocket is
accelerated, its inertia is opposed to motion, and being applied at the
centre of gravity, which is in rear of the vent, the point of
application of the moving force, it acts to prevent the rocket from
turning over in its flight. But when the composition is consumed, the
centre of gravity is thrown farther to the rear, and the velocity of the
rocket is retarded, the inertia acts in the opposite direction, and the
effect will be, if the centre of gravity or inertia is sufficiently far
to the rear, to cause it to turn over in the direction of its length. If
the rocket be directed toward the earth, this turning over will be
counteracted by the acceleration of velocity due to the weight, and the
form of the trajectory will be preserved.
_Effect of Wind._--When the wind acts obliquely to the plane of fire,
its component perpendicular to this flame acting at the centre of figure
will cause the rocket to rotate around its centre of gravity. As the
centre of figure is situated in rear of the centre of gravity, the point
will be thrown toward the wind, and the propelling force acting always
in the direction of the axis, the rocket will be urged toward the
direction of the wind. To make an allowance for the wind in firing
rockets, they should be pointed toward the opposite side from which the
wind comes, or with the wind instead of against it. If the wind act in
the plane of fire from front to rear, it will have the effect to depress
the point, and with it the elements of the trajectory in the ascending
branch, and elevate them in the descending branch; as the latter is
shorter than the former, the effect of a front wind will be to diminish
the range. The converse will be true for a rear wind.
_Kind Used._--The two sizes of Hale’s rockets in use in the American
service are, the 2-inch (interior diameter of case), weighing 6 pounds,
and 3-inch (interior diameter of case), weighing 16 pounds. Under an
angle of from 4° to 5° the range of these rockets is from 500 to 600
yards. Under an angle of 47° the range of the former is 1760 yards, and
the latter 2200.
=Rocroy=, or =Rocroi=. A small town of France, in the department of
Ardennes, 15 miles northwest from Mézières. It is memorable for the
victory gained by the great Condé (then duke of Enghien) over the
Spaniards, May 19, 1643. The Spanish army was composed of veteran bands
of Walloons, Spaniards, and Italians, and their general, Don Francisco
de Mellos, was a commander worthy of his army. The French (22,000) were
also good troops, but their general, Condé, was a young and
inexperienced officer. At first the battle was unfavorable to the
French, but at last the Spaniards were thrown into irretrievable rout.
The Count of Fuentes, the commander of the redoubtable infantry, and
10,000 of his men were among the slain; and 5000 men, with all the
cannon, many standards, and the baton of the Count de Mellos, were
captured. But, far beyond all material losses, the renown of
invincibility, first acquired by the Spanish infantry on the field of
Pavia (1525), and confirmed at St. Quentin, Gravelines, and Prague, was
destroyed.
=Rodman Gun.= See ORDNANCE, CONSTRUCTION OF.
=Roermond.= An old town in the Netherlands, province of Limburg, at the
junction of the Roer and Maas. It has often endured the horrors of being
besieged and taken.
=Rogue River Indians.= See INDIANS AND THEIR AGENCIES (Oregon).
=Rogue’s March.= Derisive music performed in driving away a person
under popular indignation, or when a soldier is drummed out of a
regiment.