bar-iron and charcoal in a close furnace for several days. When taken
out the bars are brittle in quality and crystalline in appearance. The
purpose for which the steel is to be used determines the degree of
carbonization. The best qualities of iron (Russian and Swedish) are used
for the finest kind of steel.
_Tilted Steel._--This is blistered steel moderately heated and subjected
to the action of a tilt-hammer, by which means its density and tenacity
are increased.
_Shear Steel._--A blistered or natural steel refined by piling thin bars
into fagots, and then rolling or hammering them into bars, after they
have been brought to a welding heat in a reverberatory furnace. The
quality is improved by a repetition of this process, and the steel is
known accordingly by the names, half shear, single shear, double shear,
etc.
_Cast Steel._--This is made by breaking blistered steel into small
pieces, and melting it in close crucibles from which it is poured into
iron molds. The ingot is then reduced to a bar by hammering or rolling
with great care. Cast steel is the finest kind of steel, and is best
adapted for most purposes; it is known by a very fine, even, and close
grain, and a silvery homogeneous fracture. The most remarkable specimen
of cast steel for tenacity which is on record was manufactured at
Pittsburgh, Pa. It was tested at the Washington Navy-Yard, and found to
sustain 242,000 pounds to the square inch. The strength of cast steel
usually runs from 70 to 140,000 pounds.
_Bessemer Steel._--This steel is produced by forcing air into melted
iron, by means of which the carbon and silicon of the crude cast iron is
oxidized. The essential difference between this process and the ordinary
puddling is mechanical, and consists in the intense and violent stirring
of the Bessemerized iron, to which alone is due the production and
maintenance of a temperature, without any other fuel than the carbon and
silicon contained, that keeps the metal fluid so that it can be cast
into homogeneous malleable ingots. When decarburation has been carried
far enough, the current of air is stopped, and a small quantity of white
pig-iron containing a large amount of manganese is dropped into the
liquid metal. No very large cannon have yet been made wholly of Bessemer
steel, but several small ones have, which have shown great endurance.
Experiments at the Woolwich Arsenal have shown that the tenacity of this
steel is more than doubled by hammering.
_Siemens-Martin._--In this process the ingredients of cast steel are
melted together on the open hearth of a reverberatory furnace of special
construction, and a certain proportion of manganese necessary to make a
sound and practically malleable steel added. This steel is, however,
little used in gun construction.
_Semi-Steel._--If in the process of puddling or decarbonizing cast iron
the process be stopped at a particular time, determined by indications
given by the metal to an experienced eye, an iron is obtained of greater
hardness and strength than ordinary iron, to which the name of
semi-steel, or puddled steel, has been given. The principal difficulty
in its manufacture is that of obtaining uniformity in the product,
homogeneity and solidity throughout the entire mass. It is much improved
by reheating and hammering under a heavy hammer; but it has not been
found a reliable material for even cannon of small caliber. The
celebrated guns made by Mr. Krupp of Germany are of cast steel, made
from puddled steel, and of peculiar character, combining great tensile
strength with the property of stretching to a great extent without
breaking. Sir Joseph Whitworth improves the qualities of steel for his
more recent guns by casting it under hydraulic pressure.
_Chrome Steel._--An alloy of iron and chromium, which is not steel in
the ordinary sense, but which possesses many of its characteristics. The
tensile strength and resistance to crushing is much higher than ordinary
cast steel. This material has been largely used in bridge-building, but
has not yet been applied to cannon-making.
_Bronze_ for cannon (commonly called brass) consists of 90 parts of
copper and 10 of tin, allowing a variation of one part of tin more or
less; by increasing the proportion of tin, bronze becomes harder, but
more brittle and fusible; by diminishing it it becomes too soft for
cannon, and at the same time loses a part of its elasticity. Bronze is
more fusible than copper, much less so than tin. It is harder, less
susceptible of oxidation, and much less ductile than either of its
constituents. Its fracture is of a yellowish color, with little lustre,
a coarse grain, irregular, and often exhibiting spots of tin which are
of a whitish color. The density and tenacity of bronze when cast into
the form of cannon, are found to depend upon the pressure and mode of
cooling. In consequence of the difference of fusibility of tin and
copper, the perfection of the alloy depends much on the nature of the
furnace and the treatment of the melted metal. By these means alone the
tenacity of bronze has been carried up to 60,000 pounds. Bronze is but
slightly corroded by the action of the gases evolved from gunpowder, or
by atmospheric causes; but its tin is liable to be melted away at the
sharp corners by the great heat generated in rapid firing. It is soft,
and therefore liable to serious injury by the bounding of the projectile
in the bore. This injury is augmented as the force of the rebound is
increased by the elasticity of the metal. It was established by
experiments of Maj. Wade of the U. S. Ordnance Corps more than twenty
years ago that the tensile strength of bronze is related to its density.
It has been discovered since that this density can be produced by
artificial compression. Two men claim the honors of the invention--Gen.
Uchatius of the Austrian army, and S. B. Dean, an American inventor. The
methods are essentially the same. After the gun is cast, steel mandrels
slightly conical in shape are driven through the bore by hydraulic
pressure,--each being succeeded by one slightly larger,--thus enlarging
the bore and compressing the metal surrounding it. It is claimed that
the bronze is thus rendered harder and stronger, and the defects above
cited in a large measure obviated. The term “steel bronze” or “bronze
steel” has been applied to the metal so treated. Many guns have been
made of it for the Austrian service,--the largest of which is a 6-inch
breech-loader throwing a projectile of 85 pounds. This gun has proved
itself slightly superior in power to the same sized Krupp gun of steel.
_Aluminium Bronze._--An alloy of 90 parts of copper and 10 of aluminium.
It is harder than ordinary bronze; much stronger, being 100,000 pounds
to the square inch; it does not tarnish readily. Its properties would
seem to especially fit it for a gun metal. _Phosphor bronze_ is an alloy
with very similar properties.
_Combined Metals._--Numerous trials have been made to improve the
strength of cannon by combining two or more metals in such a way that
the good qualities of one will counteract the defects of the others. But
the only metals used to any extent are those described above. Steel is
constantly gaining in favor as a cannon metal. It is now almost
exclusively employed throughout Europe, and wherever the Krupp gun is
used. The great perfection arrived at by Krupp and others in the
manufacture of steel seems to place that metal above all others for gun
construction, whilst the difficulty of handling large masses has been
overcome by the enormous power of the machinery used. Steel is also
sparingly employed both in the United States and England for converting
smooth-bore guns into rifles according to the Palliser method, but
experiments in the United States have shown that it is inferior to
wrought iron for this purpose. See ORDNANCE, CONSTRUCTION OF.
Wrought and cast iron are much used in this way for cannon in both the
United States and in England. In the former, all the larger cannon
belonging to the official system (both siege and sea-coast) are made of
the cast metal, whereas the Parrott gun and the new rifled pieces are a
combination of both. (See ORDNANCE, CONSTRUCTION OF.) The metal chiefly
employed in England is wrought iron, in combination with steel; the
largest guns made at the Woolwich Arsenal are of this nature. Bronze,
except as modified by the Austrians, has now nearly entirely gone out of
use as a cannon metal. In France and the United States, field-pieces,
mortars, and howitzers are still made of this material.
=Ordnance, Strains Upon.= The exterior form of cannon is determined by
the variable thickness of the metal which surrounds the bore at
different points of its length. In general terms, the thickness is
greatest at the seat of the charge, and least at or near the muzzle.
This arrangement is made on account of the variable action of the powder
and projectile along the bore, and the necessity of disposing the metal
in the safest and most economical manner. The pressure at different
points may be approximately determined by calculation, or, more
accurately, by experiment. In the latter method, the plan generally
employed consists in boring a series of small holes through the side of
a gun at right angles to its axis at known distances apart. A steel ball
is projected from each hole in succession into a target, or ballistic
pendulum, by the force of the charge acting through it, and the pressure
at the various points is deduced from the velocities communicated to
these balls. This method was adopted by Col. Bomford. Instead of the
projectile a steel punch may be employed, which is pressed by the force
of the charge into a piece of soft copper. (See PRESSURE-GAUGE.) The
weight necessary to make an equal indentation in the same piece is then
ascertained by a testing machine. The strains to which all fire-arms are
subjected may be classified as follows: (1) The tangential strain which
tends to split the piece open longitudinally, and is similar in its
action to the force which bursts the hoops of a barrel. (2) The
longitudinal strain which acts to pull the piece apart in the direction
of its length. Its action is greatest at or near the bottom of the
bore, and least at the muzzle, where it is nothing; these two strains
increase the volume of the metal to which they are applied. (3) A strain
of compression which acts from the axis outward to crush the truncated
wedges of which a unit of length of the piece may be supposed to
consist; this strain compresses the metal and enlarges the bore. (4) A
transverse strain which acts to break transversely by bending outward
the staves of which the piece may be supposed to consist. This strain
compresses the metal on the inner and extends it on the outer surface.
It is known that rupture will take place due to the tangential strain
alone, when three times the pressure upon a unit of surface of the bore
is greater than twice the tensile strength. Due to the longitudinal
strain alone, rupture will take place in the direction of the length,
when the pressure is greater than twice the tensile strength; and if the
transverse strain alone is considered, rupture will take place when
twice the pressure is greater than three times the tensile strength. It
therefore appears that the tendency to rupture is greater from the
action of the tangential force than from any other, and for lengths
above two, or perhaps three calibers, the tangential resistance may be
said to act alone, as the aid derived from the transverse resistance
will be but trifling for greater lengths of bore; but for lengths of
bore less than two calibers, this resistance will be aided by both the
transverse and the longitudinal resistance. Every piece should therefore
have sufficient thickness of breech to prevent splitting through the
latter; after this point has been attained, any additional thickness of
breech adds nothing to the strength of the piece. It therefore appears
that a fire-arm is strongest at or near the bottom of the bore, and that
its strength is diminished rapidly as the length of the bore increases
to a certain point (probably not more than three calibers from the
bottom); after which, for equal thickness of metal, its strength becomes
sensibly uniform. The metals of which cannon are made being crystalline
in structure, the size and arrangement of the crystals have an important
influence on its strength to resist a particular force; and a metal will
have the greatest strength with reference to a particular force when its
crystals are small, and the principal faces are parallel to the
straining force, if it be one of extension, and perpendicular to it, if
it be one of compression. The position of the principal crystalline
faces of a cooling solid is found to be perpendicular to the cooling
surface; the result of this arrangement of crystals is to create planes
of weakness where the different systems of crystals intersect. The
effect of this law upon cannons, it has been discovered, is to render
radial specimens more tenacious than those cut tangentially from the
same gun. The manner and rapidity of cooling have also a great effect
upon the ability of cannon to resist strains, and as all solid bodies
contract their size in the operation of cooling, it follows that if the
different parts of a cannon cool unequally, it will change its form,
provided it be not restrained by the presence of a superior force. If it
be so restrained, the contractile force will diminish the adhesion of
the parts by an amount which depends on the rate of cooling of the
different parts, and the contractibility of the metal. This is an
important consideration in estimating the strength and endurance of
cannon, particularly those made of cast iron. All such cannon cooled
from the exterior (see ORDNANCE, CONSTRUCTION OF) are affected by two
straining forces; the outer portion of the metal being compressed, and
the interior extended, in proportion to their distances from the neutral
axis or line composed of particles which are neither extended nor
compressed by the cooling process. The effect of this unequal
contraction may be so great as to crack the interior metal of cast iron
even before it has been subjected to the force of gunpowder. The strain
produced by the explosion of gunpowder is not distributed equally over
the thickness of metal, but it varies inversely as the square of the
distance from the centre; it therefore follows that the sides of a
cannon are not rent asunder as by a simple tensile force, but they are
torn apart like a piece of cloth, commencing at the surface of the bore.
Hence it is that the effect of ordinary cooling is to diminish the
strength and hardness of the metal of cannon at or near a point where
the greatest strength and hardness are required, _i.e._, at the surface
of the bore. The strains produced by unequal cooling increase with the
diameter of the casting and the irregularity of its form. This explains
the great difficulty found in making large cast-iron cannon
proportionally as strong as small ones, and also how projections like
bands, moldings, etc., injure the strength of cannon. It also explains
why cannon made of “light” cast iron, or cast iron made more tenacious
by partial decarbonization, are not so strong as cannon made of weaker
iron; for it is well known that such iron contracts more than the latter
in cooling, and therefore produces a greater strain of extension on the
surface of the bore. Capt. Rodman of the U. S. Ordnance Department has
proposed a plan for cooling cannon from the interior (see ORDNANCE,
CONSTRUCTION OF), thereby reversing the strains produced by external
cooling, and making them contribute to the endurance rather than to the
injury of the piece. It is likely, however, that the strains produced by
unequal cooling are modified by time, which probably allows the
particles to accommodate themselves to a certain extent to their
constrained position. In confirmation of this, great endurance has been
frequently found in _old_ solid cast guns, as in the old 42-pounders
tested about the beginning of the war, 1861-65.
=Ordnance Department.= In the United States, was first established May
14, 1812, and was not provided for in the reduction of the army in 1815,
but continued in the service. In 1821 the department was merged into the
artillery, attaching to each regiment of artillery 1 supernumerary
captain, and giving to each company 4 subaltern officers. The corps of
ordnance was re-established April 5, 1832. The department consists of 1
brigadier-general, 3 colonels, 4 lieutenant-colonels, 10 majors, 20
captains, 16 first lieutenants, and 350 enlisted men. It is the duty of
the senior officer of the ordnance department to direct the inspection
and proving of all pieces of ordnance, shot, shells, small-arms, and
equipments procured for the use of the armies of the United States; and
to direct the construction of all cannon and carriages, and every
implement and apparatus for ordnance, and all ammunition-wagons,
traveling-forges, and artificers’ wagons; the inspection and proving of
powder, and the preparation of all kinds of ammunition and ordnance
stores. It is also the duty of the senior officer of the ordnance
department to furnish estimates, and, under the direction of the
Secretary of War, to make contracts and purchases for procuring the
necessary supplies of arms, ordnance, and ordnance stores, etc. In the
British service, the ordnance department was a distinct branch of the
war department, originally for the supply of all warlike stores used in
the naval or military service. The first master of ordnance was created
in the time of Henry VIII., and the Tower of London was probably the
depot of arms and military stores; Robert, earl of Essex, is said to
have been the first master-general, in 1596. It does not appear that the
ordnance department of the British service became especially military
until the early part of the 18th century, after the organization of the
Royal Artillery, in 1743, under the Duke of Montague as master-general.
From this time the ordnance department was administered by a
master-general and board, the latter being composed of a
lieutenant-general of ordnance, surveyor-general, clerk of the ordnance,
principal store-keeper, clerk of the deliveries, and treasurer. About
1763 the department became a construction board, with charge of all
forts and fortresses, and directed the construction of all the
fortifications and military store-houses, and barracks for the ordnance
corps. The board was finally abolished as a separate department, the
duties carried on by the commander-in-chief, and the various civil
branches by separate offices under the secretary of state for war.
=Ordnance Office.= Before the invention of guns, this office was
supplied by officers under the following names: the bowyer, the
cross-bowyer, the galeater, or purveyor of helmets, the armorer, and the
keeper of the tents. Henry VIII. placed under the management of a
master-general, a lieutenant, surveyor, etc. The master-general was
chosen from among the first generals in the service of the sovereign.
The appointment was formerly for life; but since the restoration, was
held _durante bene placito_, and not unfrequently by a cabinet minister.
The letters patent for this office were revoked May 25, 1855, and its
duties vested in the minister of war. The last master-general was Lord
Fitzroy Somerset, afterwards Lord Raglan.
=Ordnance Projectile.= See PROJECTILE.
=Ordnance Sergeants.= In the U. S. service, are staff sergeants who are
selected from the sergeants of the line of the army. Their duties
consist in receiving and preserving the ordnance, arms, ammunition, and
other ordnance stores at posts, under the direction of the commanding
officer of the same. They must not be confounded with sergeants of
ordnance, who are sergeants in the ordnance detachments at arsenals,
etc.
=Ordnance Store-keeper.= In the British service, is a civil officer in
the artillery who has charge of all the stores, for which he is
accountable to the office of ordnance.
=Ordnance Store-keeper.= In the U. S. army, an officer of the ordnance
department who holds the rank of captain. The grade has been abolished
by act of Congress, and the duties appertaining to the office will be
performed by other officers of the ordnance department.
=Ordnance Stores.= See ORDNANCE.
=Oregon.= One of the Pacific States of the American Confederacy. Oregon
was the name formerly given to the whole territory north of the Rocky
Mountains, and was first claimed by the Spanish government, and next by
the government of the United States, as far as lat. 54° 40′ N. This
latter claim was resisted by the British government, which asserted a
right to the entire territory, and in 1818 a treaty was made, and
renewed in 1827, giving joint occupation to the disputed territory. In
1846 a treaty was concluded, by which the boundary was settled on the
49th parallel. Previous to this latter treaty (1839) emigration from the
United States, for the purpose of settlement, commenced, and it
continued steadily until the opening of the gold mines in California,
which attracted a great many emigrants. In 1849 it formed a Territorial
government, and in 1859 it was admitted into the Union as a State. This
State has been troubled greatly by Indians, and has been the scene of
several wars in earlier days, notably, in 1853, on Rogue River; in 1855,
when a general outbreak took place, of which the following is a brief
summary: In 1855 a war broke out between the whites and the Indians of
Washington Territory. The head and front of the outbreak on the part of
the Indians was Kam-ai-a-kin. He took this stand from a fixed principle:
that of resisting all encroachments on the part of the whites. He had
seen the fate of the Indian race in the Willamette Valley, and he
determined to anticipate such a result with regard to his own people,
and, if possible, to prevent it. When Gov. Stevens made his arbitrary
treaties with him, and left him no discretion but to sell his land; and
when the miners began to traverse his country, he concluded that the
hour had arrived to fight, and he called to his aid as many of the
adjoining tribes as he could persuade into it. The manner in which the
treaties on Puget Sound were conducted created great dissatisfaction
among the Indians, and they were quite ready to join Kam-ai-a-kin. The
war commenced by the killing of miners, who were picked off in the
Yakama country as they were going to Fort Colville, scarcely a month
after the council which was held at Walla Walla. The killing of the
agent Bolen set the war in a blaze. The small detachment of troops sent
to chastise them was driven back. This success on the part of the
Klickatats encouraged the Sound Indians, who also took up arms, and in
the absence of troops, fell upon and killed the inhabitants of White
River; but the wholesale slaughter of women and children by a party
under the command of Major Lupton on October 8, 1855, drove the Indians
to desperation and caused them to commence the war in earnest;
hostilities continued until the summer of 1856. Also, in later years,
the Modoc war (1872), the Nez Pérces (1877), and the Bannock war (1878).
=Oreillere= (_Fr._). Oreillet, ear-piece of an ancient helmet, shaped
like an oyster-shell, for protecting the ear and cheek.
=Oreillon= (_Fr._). Ear of a sword, languet, or small slip of metal on
the hilt, which, when the sword is sheathed, extends along the scabbard.