Chapter I: Definitions

In the study of any subject which is rather technical in nature, it is absolutely essential that the reader be familiar with the meaning of the words and phrases which must be used in the matter to be discussed. If the subject matter is to be understood there must be a common phraseology. The reader is therefore strongly urged to perfect his knowledge of the following short vocabulary before passing on to the matter which follows.

=Ammunition.= A general term applied to all forms of powders, shells, cartridges, primers, etc.

(a) _Fixed Ammunition._ When the powder charge is enclosed in a
metallic container which is fixed to the projectile, it is called
“=Fixed Ammunition=.”

(b) _Semi-Fixed Ammunition._ When the charge and metallic container
are a fixed unit but are not fastened to the projectile, it is called
“=Semi-Fixed Ammunition=.”

(c) _Separate Ammunition._ When the powder charge is contained in
bags separate from the projectile and containing not a fixed but a
varying charge, it is called “=Separate Ammunition=.”

=Artillery.= All firearms not carried by hand, excepting machine guns. It is divided into two general classifications: (1) artillery of position, and (2) mobile artillery.

(1) Artillery of Position is that which is permanently mounted in
fortifications.

(2) Mobile Artillery consists of two classes: first, artillery
designed to accompany an army in the field; second, railway artillery
which requires tracks for its transportation.

=Ballistics.= The science of hurling projectiles or of the motion of projectiles in their flight.

=Bore.= The hole which extends from the muzzle to the breech. The passageway for the projectile. That part of the tube which is bored out.

=Breech.= The rear end of the gun, tube, or barrel.

=Caisson.= A two-wheeled vehicle which supports an ammunition chest. The wheeled equipment of a gun section consists of one gun with its limber and one caisson with its limber. For a caisson section it consists of two caissons with their limbers.

=Caliber= (=Calibre=). The diameter between the highest points in the bore.

=Carriage, gun.= Usually understood to mean all the piece except the tube with its appurtenances and the limber.

=Cartridge case.= A hollow cylinder shaped to fit the bore. A container for the propelling charge.

=Charge.=

(a) _Propelling._ A quantity of powder used in the bore to generate
the gases which propel the projectile from the gun.

(b) _Bursting._ A quantity of powder used in shrapnel to strip off
the head of the projectile and to force out the balls.

(c) _Explosive._ The matter used in a shell to detonate it at the end
of its flight.

=Cradle.= In general, that part of the carriage which houses the recoil and counter-recoil mechanisms.

=Elevating Mechanism.= The device used to elevate the gun through a vertical arc in order to give the gun an elevation corresponding to the desired range at which the piece is to be fired.

=Fire Control Equipment.= Those instruments used to compute firing data, observe and correct the fire, such as B. C. Telescopes, Aiming Circles, Range Finders, etc.

=Firing Mechanism.= A device located in the breechblock for exploding the primer and thus causing the ignition of the powder charge.

=Fuze.= That part of the round which is fastened to the point or to the base of the projectile and causes the latter to be detonated or exploded near the time or the place desired.

=Fuze Setter.= A device used to set time fuzes in such a manner that shrapnel or shell will burst at or near the desired height in air.

=Gun.= A metallic tube from which projectiles are hurled by gases generated from the ignited powder. In general, all fire arms; but in Field Artillery terms, comparatively long-barreled weapons using relatively high muzzle velocity in contra-distinction to the howitzers and mortars.

=Howitzer.= A weapon which differs from a gun in that for the same caliber it uses a shorter tube, lower muzzle velocity and generally a more curved trajectory. From two to seven varying strengths of propelling charges may be used in the howitzer. This gives it selective angles of fall, and allows the howitzer to reach targets that are hidden from the flat trajectories of guns.

=Initial Velocity.= The speed with which the projectile first moves.

=Limber.= A two-wheeled carriage which is sometimes used to carry an ammunition chest and always used to support the weight of the trail of the piece or caisson. It adds the other two wheels to make a four-wheeled vehicle.

=Materiel.= A term used in the Field Artillery in contra-distinction to Personnel.

=Mortar.= A weapon using for the same caliber, a barrel much shorter than the corresponding howitzer. Used at short ranges with extreme steep angles of fall to reach highly defiladed targets.

=Muzzle.= The front end of the bore.

=Muzzle Velocity.= Speed or velocity of the projectile measured as it leaves the muzzle.

=Ogive.= The rounded shoulder of the projectile.

=Ordnance.= Arms, ammunition, and their accessories.

=Piece.= A fire arm, small or large.

=Primer.= Device used to insure ignition of the propelling charge.

=Projectile.= The effect-producing part of the round. The bullet-like form which is thrown toward the target.

=Quadrant, gunners.= A device for measuring angles of elevation.

=Recoil Mechanism.= That part of the piece which checks the recoil—or kick—that always occurs when a piece is fired. It generally includes the counter-recoil mechanism which restores the tube “into battery” after it has fired.

=Rifle.= A gun. A weapon with a comparatively long barrel and high muzzle velocity. Rifles under 6 inches seldom use over two different charges. Term used in contrast to Howitzer or Mortar.

=Rifling.= The lands and grooves in the bore of the piece which imparts to the projectile during its passage through the bore, the rotary motion that increases accuracy and range.

=Round.= Consists of the primer, cartridge case or powder bags, projectile and fuze. For light Field Artillery the round weighs about 18 lbs and the projectile about 15.

=Shell.= A projectile which secures its effect by the force of its detonation, the bursting of its walls, and the fragmentation and velocity of the fragments. Also used as a gas carrier.

=Shrapnel.= A projectile which secures its effect by the expulsion in the air of lead balls with shot-gun like effect.

=Trail.= That part of the piece which extends from the axle to the rear and transmits the force of recoil to the ground through the trail spade. Usually supports the elevating and traversing mechanisms.

=Traversing Mechanism.= A device used to give the piece direction by moving it through a horizontal arc.