Part 515

VENT, (Lumière, Fr.) in artillery, or, as it is vulgarly called, the touch-hole, is the opening through which the fire is conveyed to the powder that composes the charge.

As the placing the vents in mortars, howitzers, and guns in the best manner, is so very delicate a point, and about which both authors and practitioners differ, we will advance what the result of experiments has demonstrated. The most common method is to place the vent about a quarter of an inch from the bottom of the chamber or bore; though we have seen many half an inch, and some an inch from the bottom. It has always been imagined, that if the vent was to come out in the middle of the charge, the powder would be inflamed in less time than in any other case, and consequently produce the greatest range; because, if a tube be filled with powder, and lighted in the centre, the powder will be burnt in half the time it would be, were it lighted at one end. This gave a grounded supposition, that the greater the quantity of powder which burnt before the shot or shell was sensibly moved from its place, the greater force it would receive. To determine this, the king of Prussia, in 1765, ordered that a light three pounder should be cast, with three shifting vents, one at the centre of the charge, one at the bottom, and the other at an equal distance from the bottom and centre one; so that when one was used, the others were effectually stopped. The gun weighed 2 cwt. 1 qr. 20 lb.; its length was 3 feet 3 inches, and the bottom of the bore quite flat. It was loaded each time with one fourth of the shot’s weight; and it was found, that when the lowest or bottom vent was used, the shot went farthest, and the ranges of the others diminished in proportion as they were distant from the bottom. The piece was elevated to 1 degree 30 minutes.

In 1766 the same monarch caused several experiments to be tried with three small mortars of equal size and dimensions, but of different forms in their chambers; each of which held seven ounces and a half of powder. From these experiments it appeared, that the concave chamber produced the greatest ranges, and that the bottom of the chamber is the best place for vents, having in that place the greatest effect.

The vents of English guns are all ²⁄₁₀ of an inch diameter. See remark 9 of the article VELOCITY.

VENT-field, is the part of a gun or howitz between the breech mouldings and the astragal.

VENT-astragal, that part of a gun or howitzer which determines the vent-field.

VENT, Fr. That vacancy which is occasioned by the difference between the calibre of a piece of ordnance, and the diameter of its ball. See WINDAGE.

VENT, Fr. Wind. The French use this word in various senses.

VENT d’un boulet de canon, Fr. The wind of a cannon ball.

Coup de VENT, Fr. Heavy weather; a squall.

VENT reglé, Fr. A regular wind; such as the trade-wind.

Avoir du VENT, Fr. In farriery; to be pursy.

VENTS alizes, Fr. Trade winds.

VENTAIL. That part of a helmet which is made to lift up.

VENTOUSES, Fr. Air-holes, ventilators.

VENTRE, Fr. Belly; womb. When a piece of ordnance is off its carriage, and lies on the ground, it is said, among the French, to be upon its belly--etre sur le ventre.

Se coucher VENTRE à terre. To lie down flat on your face. Le capitaine ordonna à ses soldats de se coucher ventre à terre. The captain ordered his men to lie on their bellies. This frequently occurs in action, when any part of the line or detached body is so posted as to be within reach of the enemy’s cannon, and not sufficiently near to make use of its own musquetry.

Demander pardon VENTRE à terre. To ask pardon in the most abject position.

VERANDA, Ind. The covering of houses, being extended beyond the main wall of building, by means of a slanting roof, forming external rooms or passages; a colonade; balcony; gallery.

VERBAL orders. Instructions given by word of mouth, which, when communicated through an official channel, are to be considered as equally binding with written ones.

VERBAL, Fr. Verbal; given by word of mouth.

Procès VERBAL, Fr. A verbal deposition.

VERD, Fr. Green. This word is sometimes used in a figurative sense by the French, viz.

Homme VERD or VERT, Fr. A resolute man.

Tête VERTE, Fr. A giddy thoughtless fellow.

VERD pour les chevaux, Fr. Green forage or grass. In the ancien regime of France, the cavalry and dragoon horses, when quartered in a flat country, were allowed to be thirty days at grass; the particular period was left to the discretion of the commanding officers. The term was sometimes extended to forty days, without any deduction being made for the ten days; by means of which an emolument accrued to the captains of troops, not only from the horses which were actually sent to grass, but likewise for those that were returned as such.

VERDIGREASE, (Verd-de-Gris, Fr.) A kind of rust of copper, which is of great use among painters. It is also taken medicinally.

VERGE, Fr. A yard; a measure; a switch, &c.