Impetus. In gunnery, the altitude through which a heavy body must fall to acquire a velocity equal to that with which a ball is discharged from a piece.
Implement. Whatever may supply a want, especially an instrument or utensil as supplying a requisite to an end; as, the implements of war.
Implements, Equipments, and Machines. In artillery, the two former are employed in loading, pointing, and firing cannon, and in the mechanical manœuvres of artillery carriages, the latter to mount and dismount cannon from their carriages, and to transport artillery material from one part of a work to another. The implements for loading cannon are, (1) The rammer-head, a short cylindrical piece of beech or other tough wood, fixed to the end of a long stick of ash, called a staff, employed to push the charge to its place in the bore or chamber of a cannon. (2) The sponge, a woolen brush attached to the end of a staff, for the purpose of cleaning the interior of cannon and extinguishing any burning fragments of the cartridge that may remain after firing. In the field and mountain services, the rammer-head and sponge are attached to the opposite ends of the same shaft; in the siege and sea-coast services, they are attached to separate staves, except for howitzers, in which they are combined. (3) The ladle, a copper scoop attached to the end of a staff for the purpose of withdrawing the projectile of a loaded piece. (4) The worm, a species of double cork-screw attached to a staff, used in field and siege cannon to withdraw a cartridge. (5) The gunner’s [haversack] (which see). (6) The pass-box, a wooden box closed with a lid and carried by a handle attached to one end. In siege and sea-coast service, where the cartridge is large, it takes the place of the haversack. (7) The tube-pouch or primer-pouch, a small leather pouch attached to the cannoneer by a waistbelt. It contains the friction-tubes, lanyard, priming-wire, thumb-stall, etc. (8) The [budge-barrel] (which see). (9) The priming-wire, used to pick a hole in a cartridge for the passage of the flame from the vent. (10) The thumb-stall, a buckskin cushion attached to the thumb or finger to close the vent in sponging and loading. (11) The fuze-setter, a brass drift for driving a wooden fuze into a shell. (12) The fuze-mallet, made of hard wood, and used in connection with the setter. (13) The fuze-saw, a 10-inch tenon saw for cutting wooden or paper fuzes to the required length. (14) The fuze-gimlet, sometimes employed in place of the saw to open a communication with the fuze composition. (15) The fuze-auger, an instrument for regulating the time of burning of a fuze by removing a certain portion of the composition from the exterior. For this purpose it has a movable graduated scale, which regulates the depth to which the auger should penetrate. (16) The fuze-rasp, a coarse file employed in fitting a fuze-plug to a shell. (17) The fuze-plug reamer, used to enlarge the cavity of a fuze-plug after it has been driven into a projectile, to enable it to receive a paper fuze. (18) The shell-plug screw, a wood screw with a handle, used to extract a plug from a fuze-hole. (19) The fuze-extractor, worked by a screw, and is a more powerful instrument than the preceding; it is used for extracting wooden fuzes from loaded shells. (20) The fuze-wrench, made in the form of a cross or T-shaped, to unscrew percussion fuzes. (21) The mortar-scraper, a slender piece of iron with a spoon at one end and a scraper at the other, for cleaning the chamber of a mortar. (22) The gunner’s sleeves, made of flannel or serge; they are drawn over the coat-sleeves of the gunner to prevent them from being soiled while loading a mortar. (23) The funnel, made of copper, and used in pouring the bursting charge into a shell. (24) The powder-measures, made of copper, of cylindrical form, and of various sizes, for the purpose of determining the charges of shells and cannon by measurement. (25) The lanyard, a cord, one end of which has a small iron hook, and the other a wooden handle. It is used to explode the friction-tubes with which cannon for the land service are now fired. (26) The gunner’s gimlet and vent-punch, used in boring out the vent when it becomes foul. (27) [Gunner’s pincers] (which see). (28) The shell-hooks, an instrument made to fasten into the ears of a shell, for the purpose of lifting it to the muzzle of the piece. (29) The tow-hook, in field service, used in unpacking ammunition and taking projectiles from the chest. The implements for pointing are: the [gunner’s level], [gunner’s quadrant], the [breech-sight], the [pendulum-hausse], and [elevating arc]. (See appropriate headings.) The [tangent-scale], a brass plate, the lower edge of which is cut to the curve of the base-ring of the piece, and the upper formed into offsets which correspond to differences of elevation of a quarter of a degree. It is used in pointing by placing the curved edge on the base-ring, with the radius of the offset corresponding with the highest point of the ring, and sighting over the centre of the offset, and the highest point of the swell of the muzzle. The principal manœuvring implements are: the [trail handspike], the [manœuvring handspike], the [shod handspike], the [truck handspike], the [roller handspike] (see [Handspike]); the prolonge, a stout rope used to connect the lunette of the carriage and pintle-hook of the limber to move the piece short distances without limber; the sponge-bucket, made of sheet-iron, for washing the bore of the piece; the tar-bucket, also made of sheet-iron, for carrying grease for the wheels; the watering bucket, made of sole-leather, for watering the horses; the water-buckets, made of wood and bound with iron hoops. These are of two kinds,—one for the traveling-forge, and the other for the service of garrison batteries. The [drag-rope], used when necessary to employ a number of men in hauling loads, or extricating a carriage from a difficult part of the road. It has a hook at one end, a loop at the other, and six wooden handles placed about 4 feet apart. The men’s harness, similar to the drag-rope, except that the rope is stouter, and the handles are replaced by leather loops which pass over the shoulders of the men, to enable them to exert their strength to advantage. The [bill-hook], or hand-bill, used for cutting twigs. The screw-jack, a lifting-machine composed of a screw worked by a movable nut supported on a cast-iron stand. It is used in greasing carriage-wheels. Artillery machines comprise the gin (see [Gin]), the sling-cart (see [Hand-sling-cart]), the [casemate truck], the hand-cart (see [Hand-cart]), the lifting-jack, and the lever-jack. The casemate truck is composed of a stout frame of wood mounted on three barbette traverse-wheels, and is employed to move cannon and carriages through posterns and along casemate galleries. The lifting-jack is a small but powerful screw, worked by a geared nut. It is useful when the space for manœuvring is small, and the number of men limited. If the weight to be raised is sufficiently high, the lifting power is applied at the top; if it be low, it is applied at the foot. The lever-jack is another but less powerful apparatus for lifting. It consists of a lever of wood resting on a bolt, which passes through holes in two uprights. The height of the bolt is varied by passing it through different holes in the uprights (eight in number), and the power of the lever is regulated by a notched piece of cast iron screwed to the under side of the lever.
Implements, Re-loading. See [Re-loading Implements].
Impregnable. Not to be stormed, or taken by assault; incapable of being reduced by force; able successfully to resist attack; as, an impregnable fortress.
Impregnably. In an impregnable manner; in a manner to defy force; as, a place impregnably fortified.
Impress. To compel any person to serve.
Impression. The effect of an attack upon any place or body of soldiers.
Imprisonment. Officers may be sentenced to imprisonment by a general court-martial in any case where the court may have discretionary authority. General, garrison, and regimental courts-martial may sentence soldiers to imprisonment, solitary or otherwise, with or without hard labor, for various offenses enumerated in the Articles of War. A garrison or regimental court-martial, in awarding imprisonment, is limited to a period not exceeding thirty days. When a court awards solitary imprisonment as a punishment, it is necessary that the words “solitary confinement” should be expressed in the sentence. The legal imprisonment in the United States is confinement, solitary confinement, and confinement on bread and water; confinement on bread and water shall not extend over fourteen days at a time, with intervals between the periods of such confinement not less than such periods, and not exceeding eighty-four days in any one year.
Impulse. The act of impelling, or driving onward with sudden force; impulsion; the action of a force so as to produce motion suddenly, or without appreciable loss of time. Also sudden motion exciting to action; hasty inclination; influence acting unexpectedly, or with momentary force; impression; instigation; as, the troops moved forward with one impulse.