Part 41

_Appareille_, is that slope or easy ascent which leads to the platform of the bastion, or to any other work, where the artillery, &c. are brought up and carried down.

_Approaches_, are a kind of roads or passages sunk in the ground by the besiegers, whereby they approach the place under cover of the fire from the garrison.

_Area_, the superficial content of a rampart, or other work.

_Arrow_, is a work placed at the saliant angle of the glacis, and consists of two parapets, each about 40 fathoms long; this work has a communication with the covert-way, of about 24 or 28 feet broad, called a caponniere, with a ditch before it of about 5 or 6 fathom, and a traverse at the entrance, of three fathom thick, and a passage of 6 or 8 feet round it.

_Banquette_, whether single or double, is a kind of step made on the rampart of a work near the parapet, for the troops to stand upon, in order to fire over the parapet: it is generally 3 feet high when double, and 1¹⁄₂ when single, and about 3 feet broad, and 4¹⁄₂ feet lower than the parapet.

_Bastion_, is a part of the inner inclosure of a fortification, making an angle towards the field, and consists of 2 faces, 2 flanks, and an opening towards the centre of the place, called the gorge: or it is rather a large mass of earth, usually faced with sods, sometimes with brick, but rarely with stone; having the figure described.

With regard to the first invention of bastions, there are many opinions amongst authors. Some have attributed this invention to Zisca, the Bohemian; others to Achmet Bashaw, who having taken Otranto in the year 1480, fortified it in a particular manner, which is supposed to be the first instance of the use of bastions. Those who wrote on the subject of fortification 200 years ago, seem to suppose, that bastions were a gradual improvement in the ancient method of building, rather than a new thought, that any one person could claim the honor of. It is certain, however, that they were well known soon after the year 1500; for in 1546, Tartalea published _Quesiti & inventioni diverse_, in the 6th book of which he mentions, that whilst he resided at Verona (which must have been many years before) he saw bastions of a prodigious size: some finished, and others building: and there is besides, in the same book, a plan of Turin, which was then fortified with 4 bastions, and seems to have been completed some time before.

The great rule in constructing a bastion is, that every part of it may be seen and defended from some other part. Mere angles are therefore not sufficient, but flanks and faces are likewise necessary. The faces must not be less than 50 fathom, nor more than 65. The longer the flanks are the greater is the advantage which can be derived from them. They must therefore stand at right angles with the line of defence. At the same time the disposition of the flanks makes the principal part of a fortification, as on them the defence chiefly depends; and it is this that has introduced the various kinds of fortifying.

The angle of the bastion must exceed 60°; otherwise it will be too small to give room for the guns, and will either render the line of defence too long, or the flanks too short. It must therefore be either a right angle or some intermediate one between that and 60 degrees.

_Full bastions_ are best calculated for intrenchments, which are thrown up at the gorge, or by means of a cavalier, whose faces are made parallel to those of the bastion at the distance of 15 toises; having its flanks at the distance of 12 toises, and a ditch measuring 5.

_Large bastions_ have the advantage of small ones, for this palpable reason; the bastion being considered the weakest part of the body of a place, is always attacked; when there is room for troops, cannon and mortars, its natural weakness is greatly remedied.

_Gorge of a bastion_, the interval between the extremity of one flank and that of the next.

_Flat bastion._ When a bastion upon a right line is so constructed, that its demi-gorges do not form an angle, it is called a flat bastion.

_Gorge of a flat bastion_, is a right line, which terminates the distance between two flanks.

_Solid bastion_, _Full bastion_, A bastion is said to be solid or full, when the level ground within is even with the rampart; that is, when the inside is quite level, the parapet being only more elevated than the rest. Solid bastions have this advantage over others, that they afford earth enough to make a retrenchment, in case the enemy lodge themselves on the top of the bastion, and the besieged are resolved to dispute every inch of ground.

_Hollow bastion_, _Empty bastion_, is that where the level ground within is much lower than the rampart, or that part next to the parapet, where the troops are placed to defend the bastion. The disadvantage of these kinds of bastions is, the earth being so low, that when an enemy is once lodged on the rampart, there is no making a retrenchment towards the centre, but what will be under the fire of the besiegers.

_Detached bastion_, is that which is separated or cut off from the body of the place, and differs from a half moon, whose rampart and parapet are lower, and not so thick as those of the place, having the same proportion with the works of the place. Counter-guards with flanks are sometimes called detached bastions.

_Cut bastion_, is that whose saliant angle or point is cut off, instead of which it has a re-entering angle, or an angle inwards. It is used, either when the angle would, without such a contrivance, be too acute, or when water, or some other impediment, prevents the bastion from being carried to its full extent.

_Composed bastion_, is when two sides of the interior polygon are very unequal, which also renders the gorges unequal; it may not improperly be called a _forced bastion_, being as it were forced into that form.

_Deformed bastion_, is when the irregularity of the lines and angles causes the bastion to appear deformed, or out of shape.

_Demi-bastion_, is composed of one face only, has but one flank, and a demi-gorge.

_Double bastion_, is that which is raised on the plane of another bastion, but much higher; leaving 12 or 18 feet between the parapet of the lower, and the foot of the higher; and is sometimes in the nature of a cavalier.

_Regular bastion_, is that which has its true proportion of faces, flanks, and gorges.

_Irregular bastion_, is that wherein the above equality of just proportion is omitted.

_Barriers_, in fortification, a kind of rails to stop the horse or foot from rushing in upon the besieged with violence. In the middle of this kind of defence there is a moveable bar of wood, which opens or shuts at pleasure.

_Berm_, is a little space or path, of 4 to 8 feet broad, between the ditch and the talus of the parapet; it is to prevent the earth from rolling into the ditch, and serves likewise to pass and repass. As it is in some degree advantageous to the enemy, in getting footing, most of the modern engineers reject it.

_Bonnet_, in fortification, is a sort of work placed before the saliant angle of the ravelin to cover it: it consists of 2 faces, parallel to the ravelin, or perpendicular to those of the lunette. They are generally made 10 fathom broad at the ends with a ditch of the same breadth, the covert-way 6, and the glacis 20 fathom.

_Breach_, is on opening or gap made in a wall or rampart, with either cannon or mines, sufficiently wide for a body of troops to enter the works, and drive the besieged out of it.

_Practical breach_, is that where men may mount, and make a lodgment, and should be 15 or 20 feet wide.

_Capital of a work_, is an imaginary line which divides that work into two equal parts.

_Capital of a bastion_, a line drawn from the angle of the polygon to the point of the bastion, or from the point of the bastion to the centre of the gorge. These capitals are from 35 to 40 toises in length, from the point of the bastion to the place where the two demi-gorges meet; being the difference between the exterior and the interior radii.

_Caponnier_ is a passage made in a dry ditch from one work to another: when it is made from the curtain of the body of the place to the opposite ravelin, or from the front of a horn or crown-work, it has a parapet on each side, of 6 or 7 feet high, sloping in a glacis of 10 or 12 toises on the outside to the bottom of the ditch; the width within is from 20 to 25 feet, with a banquette on each side: there is a brick wall to support the earth within which only reaches within 1¹⁄₂ foot of the top, to prevent grazing shot from driving the splinters amongst the defendants.

_Caponnieres_ with two parapets may properly be called double; as there are some made with one rampart only, in dry ditches of the ravelin, and in that of its redoubt, towards the saliant angles, and to open towards the body of the place.

_Caponnieres_, made from the body of the place to the out-works, are sometimes arched over, with loop-holes to fire into the ditch. The single ones in the ditch of the ravelin and redoubt are likewise made with arches open towards the place; for by making them in this manner, the guns which defend the ditch before them, can no other way be dismounted than by mines.

_Cascanes_, in fortification, a kind of cellars made under the capital of a fortification; also subterraneous passages or galleries to discover the enemy’s mines.

_Casemate_, in fortification, is a work made under the rampart, like a cellar or cave with loop-holes to place guns in it.

_Cavaliers_, are works, raised generally within the body of the place, 10 or 12 feet higher than the rest of the works. Their most common situation is within the bastion, and they are made much in the same form: they are sometimes placed in their gorges, or on the middle of the curtain, and then are in the form of a horse-shoe, only flatter.

The use of cavaliers is, to command all the adjacent works and country round them: they are seldom or never made, but when there is a hill or rising ground which overlooks some of the works.

_Centre_, the middle point of any work. From the _centre_ of a place are drawn the first lines to lay down the form of a _fortification_.

_Centre of the bastion_, is that point where the two adjacent curtains produced intersect each other.

_Citadel_, is a kind of fort, or small fortification, of 4, 5, or 6 sides; sometimes joined to towns, &c. Citadels are always built on the most advantageous ground. They are fortified towards the city, and towards the country; being divided from the former by an esplanade, or open place: and serving in one case to overawe the inhabitants; and in the other, not only to hinder the approach of an enemy; but to become a retreat to the garrison, should the town be taken.

_Coffers._ See COFFERS.

_Command_ is when a hill or rising ground overlooks any of the works of a _fortification_, and is within reach of common shot; such a hill is said to command that work. See COMMAND.

_Complement of the curtain_, is that part of the interior side which forms the demi-gorge.

_Complement of the line of defence_, is a _horn-work_ with a _crown-work_ before it. See CROWN-WORK.

_Cordon_, in fortification, is a round projection made of stone, in a semi-circular form, whose diameter is about 1 foot, and goes quite round the wall, and within 4 feet from the upper part.

The cordon being placed on the top of the revetement of the scarp, is a considerable obstacle to the besiegers, when they attempt to storm a place by applying scaling ladders to the scarp.

_Covert-way_ is a space of five or six toises broad, extending round the counterscarp of the ditch, and covered by a parapet from six to seven feet and a half high, having a banquette: the superior part of this parapet forms a gentle slope towards the country, which terminates at the distance of twenty to twenty five toises; this slope is called the glacis.

Sometimes the covert-way is sunk 2 or 3 feet below the horizon of the field; for, as such works are never made to discover the enemy in their trenches, so this method of lowering the covert-way will give room for the fire of the lower curtain (in works that have one) to scour the esplanade; and the expence of it should be the most material objection against it.

_Counter-forts_, in fortification, are by some called _buttresses_; they are solids of masonry, built behind walls, and joined to them at 18 feet distance from the centre to centre, in order to strengthen them, especially when they sustain a rampart or terrace.

_Counter-guard_, in fortification is a work placed before the bastions to cover the opposite flanks from being seen from the covert way. It is likewise made before the ravelins.

When counter-guards are placed before the collateral bastions, they are esteemed of very great use, as the enemy cannot batter them without having first secured the possession of the counter-guards. They were first invented by Pasino, in 1579, and greatly improved by Speckle, in 1589.

_Counterscarp_, is properly the exterior talus of the ditch, or that slope which terminates its breadth, and is the further side from the body of the place. It is so called from being opposite to the scarp.

_Crown-work_, in fortification is a kind of work not unlike a crown: it has 2 fronts and 2 branches. The fronts are composed of 2 half bastions and 1 whole one: they are made before the curtain or the bastion, and generally serve to enclose some buildings which cannot be brought within the body of the place, or to cover the town-gates, or else to occupy a spot of ground which might be advantageous to an enemy. They are of such an expence, that they are rarely found in practice. The best use this work can possibly be put to, is to cover 2 joining curtains, when the sides of it will be parallel to the sides of the place, and it should be fortified with the same strength, and in the same manner.

The authors who have written on the subject, have never thought of this useful part; and we often see 2 horn-works put in practice to cover two curtains, where crown-work would do it much cheaper and much better. The crown-work is adopted for the same purposes as the horn-work.

_Crowned horn-work_, is a _horn-work_ with a _crown-work_ before it. See CROWN-WORK.

_Curtain_, in fortification, is that part of the body of the place, which joins the flank of one bastion to that of another. The straight curtains have always been preferred to the different designs which have been proposed, of which some have diminished the expence, and (at the same time) the strength of the place, others have somewhat augmented the strength, but greatly diminished its area.

_Cuvette_, _Cunette_, in fortification, is a small ditch from 15 to 20 feet broad, made in the middle of a large dry ditch, serving as a retrenchment to defend the same, or otherwise to let water into it, when it can be had during a siege.

When there is a cunette, there should be a caponniere to flank it.

_Defilement_, in fortification, is the art of disposing all the works of a fortress in such a manner, that they may be commanded by the body of the place. It also includes the relative disposition of the works, and the ground within cannon shot, so that the one may be discovered, and the other not observed.

_Demi-gorge_, is half the gorge, or entrance into the bastion, not taken directly from angle to angle, where the bastion joins the curtain, but from the angle of the flank to the centre of the bastion, or rather the angle the two curtains would make were they protracted to meet in the bastion. Mr. Landmann determines it to be the line which is formed by the prolongation of the curtain meeting the oblique radius.

_Demi-lune._ See RAVELIN.

_Descents_ in fortification, are the holes, vaults, and hollow places made by undermining the ground.

_Descents into the ditch or fossé_, are boyaux or trenches effected by the means of saps in the ground of the counterscarp, under the covert way. They are covered with madriers, or hurdles, well loaded with earth, to secure them against fire. In ditches that are full of water, the descent is made even with the surface of the water; and then the ditch is filled with fagots, fast bound, and covered with earth. In dry ditches the _descent_ is carried down to the bottom; after which, traverses are made either as lodgments for the troops, or to cover the miner. When the ditch is full of water, the _descent_ must be made over its surface; which is done by securing it with blinds or chandeliers, from being enfiladed, or by directing the course of the descent from the point of enfilade in the best way you can.

_Detached bastion._ See BASTION.

_Detached redoubt._ See REDOUBT.

_Ditch_, in fortification, is a large deep trench made round each work, generally from 12 to 22 fathom broad, and 15 to 16 feet deep: the earth dug out of it serves to raise the rampart and parapet. Almost every engineer has a particular depth and breadth for ditches; some are for narrow ones and deep, others for broad ones and shallow; and it is most certain that ditches should be regulated according to the situation. In regard to wet and dry ditches, almost all authors have given it in favor of the latter; and we shall only add, that the best of all are those which can either be filled or kept dry at pleasure.

_Wet ditches_, which have stagnant waters, are liable to great inconveniences. They are said to be well calculated to prevent sudden surprises and assaults; but we are convinced of the contrary, especially during a hard frost. Some again assert, that they stop all communication between ill-disposed persons in the garrison and the besiegers. Every man with the least experience, must be of a different opinion.

Wet ditches might certainly be so constructed, as to let the surface of the water remain 12 or 15 feet above the level of the adjacent country. In which case they would serve as large reservoirs, and not only contribute to the defence of a fortified place, but enrich the grounds by being occasionally let out. The additional value which the neighboring meadows would bear from these seasonable overflowings, might in some degree compensate for the expence of the fortification. During a siege, these waters, with proper management, must give considerable uneasiness to the enemy that invests the place.

To answer this double purpose, the ditch must be separated into several large basons, which might be filled or emptied at discretion, as often as circumstances would require.

_Dry ditches._ There are some ditches which may be filled at will; and others which cannot, except by extraordinary means. If they should be intended to answer the purpose of agriculture, aqueducts might be constructed, or the waters poured in through artificial channels. In which case the ditches would not require much depth. The glacis might be raised in such a manner as to serve to dam in the body of water, and to afford a second glacis from whence the besieger might be considerably embarrassed.

_Ditches that are lined_, ditches whose counterscarp is supported, and kept up by a stone or brick wall.

_Ditches that are not lined_, whose counterscarp is supported by earth covered with sods. These ditches are not so secure as the former, on account of the breadth which must be given to the talus, and by which an enemy might easily surprise a place.

So that ditches in fortification may be briefly distinguished under three separate heads, viz:

_Dry ditches_, which from the facility with which they may be repaired, and their capability of containing other works proper for their security, are in most instances preferable to any others.

_Wet ditches_ that are always full of water, and consequently must have bridges of communication which are liable to be destroyed very frequently during a siege.

Wet ditches are subject to many inconveniences, are ill calculated to favor sallies, and have only the solitary advantage of preventing a surprise.

The third sort of ditch has all the advantages of the other two kinds; if, as we have just observed, it can be so contrived, as to admit water occasionally into the different basons by means of aqueducts, and be drained, as circumstances may require.

_Draw-bridge._ See BRIDGE.

_Embrasures._ See EMBRASURE.

_Envelope_, is a work of earth raised occasionally in the ditch, sometimes like a plain parapet, at others like a small rampart with a parapet to it. Envelopes are generally made before weak places.

_Epaulement._ See EPAULEMENT.

_Epaule_, or the shoulder of the bastion, the angle made by the union of the face and flank.

_Escarp._ See SCARP.

_Esplanade._ See ESPLANADE.

_Exterior side of a fortification_, is the distance, or imaginary line drawn from one point of the bastion to that of the next.

_Faces_ of the bastion. See BASTION.

_Faces_, of any work, in fortification, are those parts where the rampart is made, which produce an angle pointing outwards.

_Face prolonged_, that part of the line of defence rasant, which is terminated by the curtain, and the angle of the shoulder.

_Fascine._ See FASCINES.

_Fausse bray_, is a low rampart going quite round the body of the place; its height is about 3 feet above the level ground, and its parapet is about 3 or 4 fathom distant from that of the body of the place. These works are made at a very great expence: their faces are very easily enfiladed, and their flank of course is seen in reverse: the enemy is under cover the minute he becomes master of them; and a great quantity of shells which may be thrown into them, and must of necessity lodge there, will go near to make a breach, or at worst to drive every one out. Hence they are liable to do more harm than good, and contribute no way to the defence of the place. M. Vauban only makes them before the curtains, and as such calls them tenailles.

_Flanks_, in fortification, are, generally speaking, any parts of a work, which defend another work along the outsides of its parapets.

_Flank of the bastion_, is the part between the face and the curtain; the flank of one bastion serves to defend the ditch before the curtain and face of the opposite bastion.

_Flanking_, is the same thing in fortification, as defending.

_Retired flanks_, are those made behind the line which joins the extremity of the face and the curtain, towards the capital of the bastion.

_Concave flanks_, are those which are made in the arc of a circle.

_Direct, or grazing flank_, is that which is perpendicular to the opposite face produced, and oblique or fichant, when it makes an acute angle with that face.

_Second flank._ When the face of a bastion produced does not meet the curtain at its extremity, but in some other point, then the part of the curtain between that point and the flank, is called the second flank. The modern engineers have rejected this method of fortifying. See FLANK.

_Flêche_, a work of two faces, often constructed before the glacis of a fortified place, when threatened with a siege, in order to keep the enemy as long at a distance as possible.

_Gallery_, is a passage made under ground, leading to the mines: galleries are from 4¹⁄₂ to 5 feet high, and about 3¹⁄₂ or 4 feet broad; supported at top by wooden frames, with boards over them.

_Genouilliere_, the undermost part of the rampart of a battery, or that part from the platform to the sole of the embrasures.

_Glacis_, is the part beyond the covert way, to which it serves as a parapet, and terminates towards the field in an easy slope at any required number of fathoms distance. Sometimes double glacis are made parallel to the esplanade, and at the distance of 16, or 20 fathoms.