Chapter D: Caldwell, (7)

BOMBARDIERS, artillery soldiers, who are employed in mortar and howitzer duty. They are to load them on all occasions; and in most services they load the shells and grenades, fix the fuzes, prepare the composition both for fuzes and tubes, and fire both mortars and howitzers on every occasion. In the English service, shells and grenades, composition for the same, fuzes, &c. are prepared in the laboratory by people well-skilled in that business.

In most other armies both officers and soldiers belonging to the companies of bombardiers, have an extraordinary pay, as it requires more mathematical learning to throw shells with some degree of exactness, than is requisite for the rest of the artillery. In the British service a specific number is attached to each company of artillery, and do not form a separate corps as in other countries.

BONAVOGLIE, _Fr._ a man that for a certain consideration voluntarily engages to row.

BONNET, in fortification, implies a small but useful work, that greatly annoys the enemy in their lodgments. This work consists of two faces, which make a salient angle in the nature of a ravelin, without any ditch, having only a parapet 3 feet high, and 10 or 12 feet broad. They are made at the salient angles of the glacis, outworks, and body of the place, beyond the counterscarp, and in the faussebray. See FORTIFICATION.

BONNET _à Prêtre_, or _Priest’s Cap_, in fortification, is an outwork, having three salient and two inward angles, and differs from the double tenaille only in having its sides incline inwards towards the gorge, and those of a double tenaille are parallel to each other. See FORTIFICATION.

BORDER, in military drawings, implies single or double lines, or any other ornament, round a drawing, &c.

BOOKS. There are different books made use of in the army, for the specific purposes of general and regimental economy.

_The general orderly_ BOOK is kept by the brigade major, from which the leading orders of regiments, conveying the parole and countersign, are always taken.

_The regimental orderly_ BOOK contains the peculiar instructions of corps which are given by a colonel or commanding officer to the adjutant--hence _adjutant’s orderly_ BOOK--and from him to the serjeant-major, who delivers the same to the different serjeants of companies assembled in the orderly room for that purpose--hence the _company’s orderly_ BOOK.

_The regimental_ BOOK is kept by the clerk of the regiment, and contains all the records, &c. belonging to the corps.

_The Company_ BOOK, is kept by the commanding officer of every company; and contains returns of all incidents and payments.

_The black_ BOOK is a sort of memorandum which is kept in every regiment, to describe the character and conduct of non-commissioned officers and soldiers; when and how often they have been reduced or punished, &c.

Every quarter-master belonging to the cavalry and infantry, has likewise a book which may not improperly be called a book or inventory of regimental stores, &c.

_Practice_ BOOK. Every officer of the artillery ought to have a book in which he should note every useful fact that occurs in practice.

BOOM, in marine fortification, is a long piece of timber, with which rivers or harbors are stopped, to prevent the enemy’s coming in: it is sometimes done by a cable or chain, and floated with yards, topmasts, or spars of wood lashed to it.

BORE, in gunnery, implies the cavity of the barrel of a gun, mortar, howitzer, or any other piece of ordnance.

BOSSE, _Fr._ a term used in the French artillery, to express a glass bottle which is very thin, contains four or five pounds of powder, and round the neck of which four or five matches are hung under, after it has been well-corked. A cord, two or three feet in length, is tied to the bottle, which serves to throw it. The instant the bottle breaks, the powder catches fire, and every thing within the immediate effects of the explosion is destroyed.

BOTTES, _Fr._ boots.

_Grosses_ BOTTES, _Fr._ jack-boots.

BOTTINE, _Fr._ half-boots worn by the hussars and dragoons in foreign armies.

BOUCHE, _Fr._ means the aperture or mouth of a piece of ordnance, that of a mortar, of the barrel of a musket, and of every species of fire-arms from which a ball or bullet is discharged.

BOUCHES _à feu_, _Fr._ is generally used to signify pieces of ordnance.

BOULER _la Matiere_, _Fr._ to stir up the different metals which are used in casting cannon.

BOULETS _à deux têtes_, chain-shot.

BOULEVART, _Fr._ formerly meant a _bastion_. It is no longer used as a military phrase, although it sometimes occurs in the description of works or lines which cover a whole country, and protect it from the incursions of an enemy. Thus Strasburgh and Landau may be called two principal boulevarts or bulwarks, by which France is protected on this side of the Rhine.

The elevated line or rampart which reaches from the Champs Elysées in Paris beyond the spot where the bastille was destroyed in 1789, is stiled the Boulevart.

In ancient times, when the Romans attacked any place, they raised boulevarts near the circumference of the walls. These boulevarts were 80 feet high, 300 feet broad, upon which wooden towers commanding the ramparts were erected covered on all sides with iron-work, and from which the besiegers threw upon the besieged stones, darts, fire-works, &c. to facilitate the approaches of the archers and battering rams.

BOULINER, _Fr._ a French military phrase. _Bouliner dans un camp_, means to steal or pilfer in a camp. _Un soldat boulineur_, signifies a thief.

BOURGUIGNOTE, _Fr._ Is a helmet or morion which is usually worn with a breast-plate. It is proof against pikes and swords.

BOURRELET, _Fr._ the extremity of a piece of ordnance towards its mouth. It is usually cast in the shape of a tulip on account of its aptitude to fit the construction of embrasures. Bourrelet means likewise a pad or collar.

BOURRER, _Fr._ to ram the wad or any other materials into the barrel of a fire-arm.

BOURRIQUET, _Fr._ a basket made use of in mining, to draw up the earth, and to let down whatever may be necessary for the miner.

BOUSSOLE, _Fr._ a compass which every miner must be in possession of to direct him in his work.

BOUTE-SELLE, _Fr._ the signal or word which is given to the cavalry to saddle their horses.

BOUTON, _Fr._ the sight of a musquet.

BOW, an ancient weapon of offence, made of steel, wood, or other elastic matter; which, after being bent by means of a string fastened to its two ends, in returning to its natural state, throws out an arrow with prodigious force.

The use of the bow is, without all doubt, of the earliest antiquity. It has likewise been the most universal of all weapons, having obtained amongst the most barbarous and remote people, who had the least communication with the rest of mankind.

The bow is a weapon of offence amongst the inhabitants of Asia, Africa, and America, at this day; and in Europe, before the invention of fire-arms, a part of the infantry was armed with bows. Lewis XII. first abolished the use of them in France, introducing, in their stead, the halbert, pike, and broadsword. The long-bow was formerly in great use in England, and many laws were made to encourage the use of it. The parliament under Henry VII. complained of the disuse of long bows, theretofore the safeguard and defence of that kingdom, and the dread and terror of its enemies.

_Cross_-BOW, is likewise an ancient weapon of offence, of the eleventh century. Philip II. surnamed the Conqueror, introduced cross-bows into France. In this reign Richard I. of England, was killed by a cross-bow at the siege of Chalus.

BOWMAN. See ARCHER.

BOWYER. The man who made or repaired the military bows was so called.

BOXES, in military affairs, are of several sorts, and for various purposes.

_Battery_-BOXES. See BATTERY.

_Cartouch_-BOXES. See CARTOUCH.

_Nave_ BOXES, are made of iron or brass, and fastened one at each end of the nave, to prevent the arms of the axle-tree, about which the boxes turn, from causing too much friction.

_Tin_-BOXES, such as are filled with small shot for grape, according to the size of the gun they are to be fired out of.

_Wood_-BOXES, with lids, for holding grape-shot, &c. each calibre has its own, distinguished by marks of the calibre on the lid.

BOXES _for Ammunition_. The dimensions of the common ammunition boxes vary according to the ammunition they are made to contain, in order that it may pack tight: this variation, however, is confined to a few inches, and does not exceed the following numbers.

Table of general dimensions of Ammunition Boxes.

----+------------------------+------
| Exterior. |Weight
+-------+-------+--------+ when
| Len. | Bre. | Depth. |empty.
----+-------+-------+--------+------
|ft. in.|ft. in.|ft. in. | lbs.
From| 2 2 | 0 10 | 0 8¹⁄₂| 20
To | 2 9 | 1 6 | 1 6 | 30
----+-------+-------+--------+------

Weight when filled, and number contained in each.

------------------------------------+--------------+---------
| | No. of
| Weight of | Rounds
| Boxes when |contained
| filled with | in each
Kinds of Ammunition. | Ammunition. | Box.
------------------------------------+--------------+---------
|cwt. qrs. lbs.| No.
{12 Prs.{ Round | 1 1 10 | 8
Boxes for { { Case. | 0 3 15 | 6
shot fixed { 6 Prs. {Round | 1 2 7 | 12
with { {Case. | 1 0 15 | 12
powder. { 3 Prs.{ Round | 0 2 25 | 16
{ { Case. | 0 2 23 | 14
{24 Prs.{ Round | 1 1 26 | 6
{ { Case. | 2 0 0 | 6
{12 Prs. {Round | 1 2 20 | 12
Box. for shot{ {Case. | 1 2 22 | 8
fixed to wood{ 6 Prs.{ Round | 1 2 20 | 24
bottoms { { Case. | 1 1 12 | 18
without { 3 Prs. {Round | 1 1 0 | 30
powder. { {Case. | 1 1 0 | 30
{How’r {8 | 1 2 2 | 3
{Case. {5¹⁄₂ | 1 2 12 | 10
{ {4¹⁄₂ | 1 2 22 | 20
Boxes {How’r {8 } | 1 2 2 | 3
for {Shells.{5¹⁄₂ }fixed. | 1 2 12 | 10
Shells. { {4¹⁄₂[7]} | 1 2 22 | 20
------------------------------------+--------------+---------

[7] Shells called four and an half, are really four and two-fifths.

The common ammunition waggon will hold from 9 to 13 of these boxes in one tier.

The tonnage of ammunition in boxes is equal to its weight: about 12 boxes make one ton.

BOYAU, in fortification, is a particular trench separated from the others, which, in winding about, incloses different spaces of ground, and runs parallel with the works of the place, that it may not be enfiladed. When two attacks are made at once, one near to the other, the boyau makes a communication between the trenches, and serves as a line of contravallation, not only to hinder the sallies of the besieged, but likewise to secure the miners.

BRACES, in a military sense, are a kind of armor for the arm: they were formerly a part of a coat of mail.

BRACKETS, in gunnery, are the cheeks of the travelling carriage of a mortar; they are made of strong wooden planks. This name is also given to that part of a large mortar-bed, where the trunnions are placed, for the elevation of the mortar: they are sometimes made of wood, and more frequently of iron, of almost a semicircular figure, well fastened with nails and strong plates.

BRANCH. See MINE and GALLERY.

BRAND, an ancient term for a sword; so called by the Saxons.

BRAQUER, _Fr._ is improperly used to express the movement of a cannon to any particular side. The correct expression is, to point the cannon, _pointer le canon_.

BRASSARTS, _Fr._ thin plates of beaten iron which were anciently used to cover the arms above the coat of mail.

Brassarts and cuirasses were worn in the days of St. Louis.

BRASSER _la Matiere_, _Fr._ to mix the different ingredients which are required for the making of gunpowder or other combustible matter.

BREACH, in fortification, a gap, or opening, in any part of the works of a fortified place, made by the artillery or mines of the besiegers, preparatory to the making an assault.

The batteries to make a breach, should commence by marking out as near as possible, the extent of the breach intended to be made; first, by a horizontal line within a fathom of the bottom of the revetement in a dry ditch, and close to the water’s edge in a wet one; and then by lines perpendicular to this line, at short distances from each other, as high as the cordon; then, by continuing to deepen all these cuts, the wall will give way in a body. The guns to produce the greatest effect should be fired as near as possible in _salvos_ or vollies. The breach should be one third the length of the face, from the centre towards the flanked angle. When the wall has given way, the firing must be continued to make the slope of the breach practicable.

Four 24 pounders from the lodgement in the covert way will effect a breach in 4 or 5 days, which may be made practicable in 3 days more.

Another way of making a breach is by piercing the wall sufficiently to admit two or three miners, who cross the ditch, and make their entry during the night into the wall, where they establish two or three small mines, sufficient to make a breach. See ARTILLERY at Siege; see also BATTERY.

_To repair a_ BREACH, is to stop or fill up the gap with gabions, fascines, &c. and prevent the assault.

_To fortify a_ BREACH, is to render it inaccessible by means of chevaux-de-frize, crow’s-feet, &c.

_To make a lodgment in the_ BREACH. After the besieged are driven away, the besiegers secure themselves against any future attack in the breach.

_To clear the_ BREACH, that is, to remove the ruins, that it may be the better defended.

BREAK _off_, a term used when cavalry or infantry are ordered to diminish its front. It is also used to signify wheeling from line; as BREAKING-off to the left, for _wheeling_ to the left.

BREAK-_Ground_, the first opening of the earth to form entrenchments, as at the commencement of a siege. It applies also to the striking of tents and quitting the ground on which any troops had been encamped.

_To_ BREAK _ground_, to begin, to open and work at the trenches in a siege, &c.

BREAST PLATE, in military antiquity, a piece of defensive armor worn on the breast of both men and horses. They are but seldom used now.

BREAST-_work_ See PARAPET.

BREECH _of a gun_, the end near the vent. See CANNON.

BREVET _rank_, is a rank in the army higher than that for which you receive pay; and gives a precedence (when corps are brigaded) to the date of the brevet commission.

BREVET, _Fr._ commission, appointment. Under the old government of France it consisted in letters or appointments signed by the king, by virtue of which every officer was authorised to discharge his particular duty. All officers in the old French service, from a cornet or sub-lieutenant up to a marshal of France were stiled _Officiers à Brévet_.

BREVET _d’Assurance ou de Retenue d’Argent_, _Fr._ certain military and civil appointments granted by the old kings of France, which were distinguished from other places of trust, in as much as every successor was obliged to pay a certain sum of money to the heirs of the deceased, or for the discharge of his debts. Hence the term _brevet d’Assurance ou de retenue_.

BRICKS, in military architecture, supply the place of stone in common buildings, and are composed of an earthy matter, hardened by art, to a resemblance of that kind: they may be very well considered as artificial stone. The Greeks and Romans, &c. generally used bricks in their buildings, witness the Pantheon, &c. In the east they baked their bricks in the sun. The Romans used them unburnt, having first left them to dry in the air for 3, 4, or 5 years.

The best _bricks_ must not be made of any earth that abounds with sand or gravel, not of such as is gritty or stony; but of a greyish marle, or yellow clay, or at least of reddish earth. But if there is a necessity to use that which is sandy, choice should be made of that which is tough and strong.

The best season for making _bricks_ is the spring; because they are subject to crack, when made in the summer: the loam should be well steeped or soaked, and wrought with water. They are shaped in a mould, and, after some drying in the sun or air, are burnt to a hardness. This is our manner of making bricks; but whether they were always made in this manner admits a doubt. We are not clear what was the use of straw in the bricks for building in Egypt, or why in some part of Germany they mix saw-dust in their clay for bricks.

We are in general tied down by custom to one form, and one size; which is truly ridiculous: 8 or 9 inches in length, and 4 in breadth, is the general measure: but beyond doubt there might be other forms, and other sizes, introduced very advantageously.

_Compass_ BRICKS, are of a circular form; their use is for steening of walls; we have also concave, and semi-cylindrical, used for different purposes.

_Grey-Stocks_, are made of the purest earth, and better wrought: they are used in front in building, being the strongest and handsomest of this kind.

_Place_-BRICKS, are made of the same earth, or worse, and being carelessly put out of hand, are therefore weaker and more brittle, and are only used out of sight, and where little stress is laid on them.

_Red Stocks_, are made of a particular earth, well wrought, and little injured by mixtures: they are used in fine work, and ornaments.

_Hedgerly_ BRICKS, are made of a yellowish colored loam, very hard to the touch, containing a great quantity of sand: their particular excellence is, that they will bear the greatest violence of fire without hurt.

BRICOLE, an improved kind of traces used by the French in drawing and manœuvring artillery; analogous to the old drag rope, but having the addition of a leather strap or girdle with a buckle, to which the drag is affixed; and an iron ring and hook at the end to drag by.

BRIDGES. Manner of laying a pontoon bridge across a river.

The bank on each side, where the ends of the bridge are to be, must be made solid and firm, by means of fascines, or otherwise. One end of the cable must be carried across the river; and being fixed to a picket, or any thing firm, must be drawn tight by means of a capstan, across where the heads of the boats are to be ranged. The boats are then launched, having on board each two men, and the necessary ropes, &c. and are floated _down_ the stream, under the cable, to which they are lashed endwise, by the rings and small ropes, at equal distances, and about their own breadth asunder; more or less, according to the strength required. If the river be very rapid, a second cable must be stretched across it, parallel to the first, and at the distance of the length of the boats; and to which the other ends of the boats must be lashed. The spring lines are then lashed diagonally from one boat to the other, to brace them tight; and the anchors, if necessary, carried out, up the stream, and fixed to the cable or sheer line across the river. One of the chesses is then laid on the edge of the bank, at each end of the bridge, bottom up; these serve to lay the ends of the baulks upon, and as a direction for placing them at the proper distances, to fit the chesses that cover the bridge. The baulks should then be laid across the boats, and keyed together: their numbers proportioned to the strength required in the bridge. If the gangboards are laid across the heads and sterns of the boats from one side of the river to the other, they will give the men a footing for doing the rest of the work. Across the baulks are laid the chesses, one after another, the edges to meet; and the baulks running between the cross pieces on the under side of the chesses. The gangboards are then laid across the ends of the chesses on each edge of the bridge.

Precautions for passing a bridge of boats.

Whatever size the bridge may be, infantry should never be allowed to pass at the same time with carriages or cavalry. The carriages should always move at a certain distance behind each other, that the bridge may not be shook, by being overloaded. The horses should not be allowed to trot over the bridge; and the cavalry should dismount and lead their horses over. Large flocks of cattle must not be allowed to cross at once.

For the dimensions, weight, and equipage of a pontoon, see the word _Pontoon_.

When bridges are made to facilitate the communication between different parts of the approaches at a siege, they should, if possible, be placed above the town; or the besieged will take advantage of the current to float down large trees, or other bodies, in order to destroy the bridge. Two of such bridges should always be placed close to each other, in order to prevent the confusion of crossing and recrossing on the same bridge; the one being intended to pass over one way, and the other to return. Pontoon bridges will generally not support a greater weight than 4 or 5,000 pounds. Pontoons, when united as a bridge, will no doubt bear more in proportion, than when acted upon separately: but the weight which a pontoon will bear may be easily ascertained, by loading it with water till it sinks to any required depth, and then by calculating the number of cubic feet of water it contains, ascertain the number of pounds required to sink it to that particular depth.

BRIDGES, in military affairs, are of several sorts and denominations, viz.

_Rush_-BRIDGES, are made of large bundles of rushes, bound fast together, over which planks are laid, and fastened: these are put in marshy places, for an army to pass over on any emergency.

_Pendant_ or _hanging_ BRIDGES, are those not supported by posts, pillars, or butments, but hung at large in the air, sustained only at the two ends; as the new bridge at the Falls of Schuylkill, five miles from Philadelphia, 1809.

_Draw_-BRIDGE, that which is fastened with hinges at one end only, so that the other may be drawn up (in which case the bridge is almost perpendicular) to hinder the passage of a ditch, &c. There are others made to draw back and hinder the passage; and some that open in the middle; one half of which turns away to one side, and the other half to the other, and both again join at pleasure.

_Flying_-BRIDGE, is generally made of two small bridges, laid one over the other, in such a manner that the uppermost stretches, and runs out by the help of certain cords running through pullies placed along the sides of the upper bridge, which push it forwards, till the end of it joins the place it is intended to be fixed on. They are frequently used to surprise works, or out-posts that have but narrow ditches. There is a curious bridge of this kind on the Ohio, worthy of attention.

BRIDGE _of boats_, is a number of common boats joined parallel to each other, at the distance of 6 feet, till they reach across the river; which being covered with strong planks, and fastened with anchors and ropes, the troops march over.

BRIDGE _of communication_, is that made over a river, by which two armies, or forts, which are separated by that river, have a free communication with one another.

_Floating_-BRIDGE, a bridge made use of in form of a work in fortification called a redoubt; consisting of two boats, covered with planks, which are solidly framed, so as to bear either horse or artillery. Bridges of this kind are frequently used.

Floating bridges made of large logs of light timber bound together with a floor along them are common in the United States.

_Ponton_-BRIDGE, a number of tin or copper boats placed at the distance of 7 or 8 feet asunder, each fastened with an anchor, or a strong rope that goes across the river, running through the rings of the pontons. They are covered with baulks, and then with chests or planks, for the army to march over. See PONTON.

_Cask_, or _Barrel_ BRIDGE, a number of empty casks that support baulks and planks, made as above into a bridge, where pontons, &c. are wanting. Experience has taught us that 5 ton of empty casks will support above water 9000 pounds: hence any calculation may be made.

BRIDGES are made of carpentry or masonry. The number of arches of a bridge is generally made odd; either that the middle of the stream or chief current may flow freely without interruption of a pier; or that the two halves of the bridge, by gradually rising from the ends to the middle, may there meet in the highest and largest arch; or else, for the sake of grace, that by being open in the middle, the eye in viewing it may look directly through there as we always expect to do in looking at it, and without which opening we generally feel a disappointment in viewing it.

If the bridge be equally high throughout, the arches, being all of a height, are made all of a size, which causes a great saving of centering. If the bridge be higher in the middle than at the ends, let the arches decrease from the middle towards each end, but so that each half have the arches exactly alike, and that they decrease in span proportionally to their height, so as to be always the same kind of figure. Bridges should rather be of few and large arches, than of many and small ones, if the height and situation will allow of it.

Names of all the terms, peculiar to BRIDGES, &c.

_Abutment._ See _Butments_.

_Arch_, an opening of a bridge, through or under which the water, &c. passes, and which is supported by piers or butments. Arches are denominated circular, elliptical, cycloidal, caternarian, equilibrial, gothic, &c. according to their figure or curve.

_Archivolt_, the curve or line formed by the upper sides of the voussoirs or arch-stones. It is parallel to the intrados or under side of the arch when the voussoirs are all of the same length; otherwise not.

By the archivolt is also sometimes understood the whole set of voussoirs.

_Banquet_, the raised foot-path at the sides of the bridge next the parapet: it is generally raised about a foot above the middle or horse-passage, and 3, 4, 5, 6, or 7, &c. feet broad, according to the size of the bridge, and paved with large stones, whose length is equal to the breadth of the walk.

_Battardeau_, or _Coffer-dam_, a case of piling, &c. without a bottom, fixed in the river, water-tight or nearly so, by which to lay the bottom dry for a space large enough to build the pier on. When it is fixed, its sides reaching above the level of the water, the water is pumped out of it, or drawn off by engines, &c. till the space be dry; and it is kept so by the same means, until the pier is built up in it, and then the materials of it are drawn up again. Battardeaux are made in various manners, either by a single inclosure, or by a double one, with clay or chalk rammed in between the two, to prevent the water from coming through the sides: and these inclosures are also made either with piles only, driven close by one another, and sometimes notched or dove-tailed into each other, or with piles grooved in the sides, driven in at a distance from one another, and boards let down between them in the grooves.

_Butments_, are the extremities of a bridge, by which it joins to, or abuts upon, the land, or sides of the river, &c.

These must be made very secure, quite immoveable, and more than barely sufficient to resist the drift of its adjacent arch, so that, if there are not rocks or very solid banks to raise them against, they must be well re-inforced with proper walls or returns, &c.

_Caisson_, a kind of chest, or flat-bottomed boat, in which a pier is built, then sunk to the bed of the river, and the sides loosened and taken off from the bottom, by a contrivance for that purpose; the bottom of it being left under the pier as a foundation. It is evident, therefore, that the bottoms of the caissons must be made very strong and fit for the foundations of the piers. The caisson is kept afloat till the pier be built to the height of low water mark; and for that purpose, its sides must either be made of more than that height at first, or else gradually raised to it, as it sinks by the weight of the work, so as always to keep its top above water: and therefore the sides must be made very strong, and kept asunder by cross-timbers within, lest the great pressure of the ambient water crush the sides in, and so not only endanger the work, but also drown the workmen within it. The caisson is made of the shape of the pier, but some feet wider on every side to make room for the men to work; the whole of the sides are of two pieces, both joined to the bottom quite round, and to each other at the salient angle, so as to be disengaged from the bottom, and from each other, when the pier is raised to the desired height, and sunk. It is also convenient to have a little sluice made in the bottom, occasionally to open and shut, to sink the caisson and pier sometimes by, before it be finished, to try if it bottom level and rightly; for by opening the sluice, the water will rush in and fill it to the height of the exterior water, and the weight of the work already built will sink it: then by shutting the sluice again, and pumping out the water, it will be made to float again, and the rest of the work may be completed. It must not however be sunk except when the sides are high enough to reach above the surface of the water, otherwise it cannot be raised and laid dry again. Mr. Labelye states, that the caissons in which he built Westminster bridge, London, contained above 150 load of fir timber, of 40 cubic feet each, and were of more tonnage or capacity than a 40 gun ship of war.

_Centres_, are the timber frames erected in the spaces of the arches to turn them on, by building on them the voussoirs of the arch. As the centre serves as a foundation for the arch to be built on, when the arch is completed, that foundation is struck from under it, to make way for the water and navigation, and then the arch will stand of itself from its curved figure. The centre must be constructed of the exact figure of the intended arch, convex, as the arch is concave, to receive it on as a mould. If the form be circular, the curve is struck from a central point by a radius; if it be elliptical, it should be struck with a double cord, passing over two pins fixed in the focusses, as the mathematicians describe their ellipses; and not by striking different pieces or arcs of circles from several centres; for these will form no ellipsis at all, but an irregular misshapen curve made up of broken pieces of different circular arches; but if the arch be of any other form, the several abscissas and ordinates should be calculated; then their corresponding lengths, transferred to the centering, will give so many points of the curve; by bending a bow of pliable matter, according to those points, the curve may be drawn.

The centres are constructed of beams of timber, firmly pinned and bound together, into one entire compact frame, covered smooth at top with planks or boards to place the voussoirs on; the whole supported by off-sets in the sides of the piers, and by piles driven into the bed of the river, and capable of being raised and depressed by wedges contrived for that purpose, and for taking them down when the arch is completed. They should also be constructed of a strength more than sufficient to bear the weight of the arch.

In taking the centre down, first let it down a little, all in a piece, by easing some of the wedges; then let it rest a few days to try if the arch makes any efforts to fall, or any joints open, or any stones crush or crack, &c. that the damage may be repaired before the centre is entirely removed, which is not to be done till the arch ceases to make any visible efforts.

_Chest._ See CAISSON.

_Coffer-dam._ See BATTARDEAU.

_Drift_, _Shoot_, or _Thrust_, of an arch, is the push or force which it exerts in the direction of the length of the bridge. This force arises from the perpendicular gravitation of the stones of the arch, which being kept from descending by the form of the arch, and the resistance of the pier, exert their force in a lateral or horizontal direction. This force is computed in _Prop. 10_, of Mr. Hutton’s _Principles of Bridges_, where the thickness of the pier is determined that is necessary to resist it, and is greater the lower the arch is, _cæteris paribus_.

_Elevation_, the orthographic projection of the front of a bridge, on the vertical plane, parallel to its length. This is necessary to shew the form and dimensions of the arches and other parts, as to height and breadth, and therefore has a plain scale annexed to it, to measure the parts by. It also shews the manner of working up and decorating the fronts of the bridge.

_Extrados_, the exterior curvature or line of an arch. In the propositions of the second section in Professor Hutton’s _Principles of Bridges_, it is the outer or upper line of the wall above the arch; but it often means only the upper or exterior curve of the voussoirs.

_Foundations_, the bottoms of the piers, &c. or the bases on which they are built. These bottoms are always to be made with projections, greater or less, according to the spaces on which they are built: and according to the nature of the ground, depth and velocity of water, &c. the foundations are laid and the piers built after different manners, either in caissons, in battardeaux, on stilts with sterlings, &c. for the particular method of doing which, see each under its respective term.

The most obvious and simple method of laying the foundations and raising the piers up to the water-mark, is to turn the river out of its course above the place or the bridge, into a new channel cut for it near the place where it makes an elbow or turn; then the piers are built on dry ground, and the water turned into its old course again; the new one being securely banked up. This is certainly the best method, when the new channel can be easily and conveniently made. This, however, is seldom or never the case.

Another method is, to lay only the space of each pier dry till it be built, by surrounding it with piles and planks driven down into the bed of the river, so close together as to exclude the water from coming in; then the water is pumped out of the inclosed space, the pier built in it, and lastly the piles and planks drawn up. This is coffer-dam work, but evidently cannot be practised if the bottom be of a loose consistence, admitting the water to ooze and spring up through it.

When neither the whole nor part of the river can be easily laid dry as above, other methods are to be used; such as to build either in caissons or on stilts, both which methods are described under their proper words; or yet by another method, which hath, though seldom, been sometimes used, without laying the bottom dry, and which is thus: the pier is built upon strong rafts or gratings of timber, well bound together, and buoyed up on the surface of the water by strong cables, fixed to the other floats or machines, till the pier is built; the whole is then gently let down to the bottom, which must be made level for the purpose; but of these methods, that of building in caissons is best.

But before the pier can be built in any manner, the ground at the bottom must be well secured, and made quite good and safe, if it be not so naturally. The space must be bored into, to try the consistence of the ground; and if a good bottom of stone, or firm gravel, clay, &c. be met with, within a moderate depth below the bed of the river, the loose sand, &c. must be removed and digged out to it, and the foundation laid on the firm bottom on a strong grating or base of timber made much broader every way than the pier, that there may be the greater base to press on, to prevent its being sunk; but if a solid bottom cannot be found at a convenient depth to dig to, the space must then be driven full of strong piles, whose tops must be sawed off level some feet below the bed of the water, the sand having been previously dug out for that purpose; and then the foundation on a grating of timber laid on their tops as before: or, when the bottom is not good, if it be made level, and a strong grating of timber, 2, 3, or 4 times as large as the base of the pier be made, it will form a good base to build on, its great size preventing it from sinking. In driving the piles, begin at the middle, and proceed outwards all the way to the borders or margin; the reason of which is, that if the outer ones were driven first, the earth of the inner space would be thereby so jammed together, as not to allow the inner piles to be driven; and besides the piles immediately under the piers, it is also very prudent to drive in a single, double, or triple row of them round, and close to the frame of the foundation, cutting them off a little above it, to secure it from slipping aside out of its place, and to bind the ground under the pier firmer: for, as the safety of the whole bridge depends on the foundation, too much care cannot be used to have the bottom made quite secure.

_Jettée_, the border made round the stilts under a pier. See STERLING.

_Impost_, is the part of the pier on which the feet of the arches stand, or from which they spring.

_Key-stone_, the middle voussoir, or the arch-stone in the top or immediately over the centre of the arch. The length of the key-stone, or thickness of the archivolt at top, is allowed to be about ¹⁄₁₅th or ¹⁄₁₆th of the span, by the best architects.

_Orthography_, the elevation of a bridge, or front view, as seen at an infinite distance.

_Parapet_, the breast-wall made on the top of a bridge to prevent passengers from falling over. In good bridges, to build the parapet but a little part of its height close or solid, and upon that a balustrade to above a man’s height, has an elegant effect.

_Piers_, the walls built for the support of the arches, and from which they spring as their bases. They should be built of large blocks of stone, solid throughout, and cramped together with iron, which will make the whole as one solid stone. Their faces or ends, from the base up to high-water-mark, should project sharp out with a salient angle, to divide the stream: or, perhaps the bottom of the pier should be built flat or square up to about half the height of low-water-mark, to allow a lodgement against it for the sand and mud, to go over the foundation; lest, by being kept bare, the water should in time undermine, and so ruin or injure it. The best form of the projection for dividing the stream, is the triangle; and the longer it is, or the more acute the salient angle, the better it will divide it, and the less will the force of the water be against the pier; but it may be sufficient to make that angle a right one, as it will make the work stronger; and in that case the perpendicular projection will be equal to half the breadth or thickness of the pier. In rivers, on which large heavy craft navigate and pass the arches, it may, perhaps, be better to make the ends semicircular: for, although it does not divide the water so well as the triangle, it will both better turn off and bear the shock of the craft.

The thickness of the piers should be such as will make them of weight or strength sufficient to support their interjacent arch independent of any other arches; and then, if the middle of the pier be run up to its full height, the centering may be struck to be used in another arch before the hanches are filled up. The whole theory of the piers may be seen in the third section of Professor Hutton’s _Principles of Bridges_.

They should be made with a broad bottom on the foundation, and gradually diminishing in thickness by off-sets up to low-water-mark.

_Piles_, are timbers driven into the bed of the river for various purposes, and are either round, square, or flat like planks. They may be of any wood which will not rot under water; but oak and fir are mostly used, especially the latter, on account of its length, straightness, and cheapness. They are shod with a pointed iron at the bottom, the better to penetrate into the ground, and are bound with a strong iron band or ring at top, to prevent them from being split by the violent strokes of the ram by which they are driven down.

Piles are either used to build the foundations on, or they are driven about the pier as a border of defence, or to support the centres on; and in this case, when the centreing is removed, they must either be drawn up, or sawed off very low under water; but it is better to saw them off and leave them sticking in the bottom, lest the drawing of them out should loosen the ground about the foundation of the pier. Those to build on, are either such as are cut off by the bottom of the water, or rather a few feet within the bed of the river; or else such as are cut off at low-water mark, and then they are called stilts. Those to form borders of defence, are rows driven in close by the frame of a foundation, to keep it firm, or else they are to form a case or jettée about the stilts, to keep the stones within it, that are thrown in to fill it up: in this case, the piles are grooved, driven at a little distance from each other, and _plank-piles_ let into the grooves between them, and driven down also, till the whole space is surrounded. Besides using this for stilts, it is sometimes necessary to surround a stone pier with a sterling, or jettée, and fill it up with stones to secure an injured pier from being still more damaged, and the whole bridge ruined. The piles to support the centres may also serve as a border of piling to secure the foundation, cutting them off low enough after the centre is removed.

_Pile-driver_, an engine for driving down the piles. It consists of a large ram or iron sliding perpendicularly down between two guide posts; which being lifted up to the top of them, and there let fall from a great height, comes down upon the top of the pile with a violent blow. It is worked either with men or horses, and either with or without wheel-work. The bridge on Schuylkill, Philadelphia, is a master-piece of workmanship; and the new bridge at Trenton, over the Delaware, is equally bold and ingenious in its plan--in the latter the floor is suspended from the voussoirs of the arches, by stirrups of iron.

_Pitch_, of an arch, the perpendicular height from the spring or impost to the key stone.

_Plan_, of any part, as of the foundations, or piers, or superstructure, is the orthographic projection of it on a plane parallel to the horizon.

_Push_, of an arch. See DRIFT.

_Salient angle_, of a pier, the projection of the end against the stream, to divide itself. The right-lined angle best divides the stream, and the more acute, the better for that purpose; but the right angle is generally used, as making the best masonry. A semicircular end, though it does not divide the stream so well, is sometimes better in large navigable rivers, as it carries the craft the better off, or bears their shocks the better.

_Shoot_, of an arch. See DRIFT.

_Springers_, are the first or lowest stones of an arch, being those at its feet, and bearing immediately on the impost.

_Sterlings_, or _Jettées_, a kind of case made about a pier of stilts, &c. to secure it, and is particularly described under the next word, _Stilts_.

_Stilts_, a set of piles driven into the space intended for the pier, whose tops being sawed level off, above low-water mark, the pier is then raised on them. This method was formerly used when the bottom of the river could not be laid dry; and these stilts were surrounded, at a few feet distance, by a row of piles and planks, &c. close to them like a coffer-dam, and called a _sterling_, or _jettée_; after which loose stones, &c. are thrown or poured down into the space, till it is filled up to the top, by that means forming a kind of pier of rubble of loose work, and which is kept together by the sides or sterlings: this is then paved level at the top, and the arches turned upon it. This method was formerly much used, most of the large old bridges in England being erected that way, such as London bridge, Newcastle bridge, Rochester bridge, &c. But the inconveniences attending it are so great, that it is now quite disused; for, because of the loose composition of the piers, they must be made very large or broad, or else the arch must push them over, and rush down as soon as the centre was drawn; which great breadth of piers and sterlings so much contracts the passage of the water, as not only very much to incommode the navigation through the arch, from the fall and quick motion of the water; but likewise to put the bridge itself in much danger, especially in time of floods, when the water is too much for the passage. Add to this, that besides the danger there is of the pier bursting out the sterlings, they are also subject to much decay and damage by the velocity of the water and the craft passing through the arches.

_Thrust._ See DRIFT.

_Voussoirs_, the stones which immediately form the arch, their undersides constituting the intrados. The middle one, or key-stone, should be about ¹⁄₁₅th or ¹⁄₁₆th of the span, as has been observed; and the rest should increase in size all the way down to the impost: the more they increase the better, as they will the better bear the great weight which rests upon them without being crushed; and also will bind the firmer together. Their joints should also be cut perpendicular to the curve of the intrados. For more information, see Professor Hutton’s _Principles of Bridges_, in 8vo.

BRIDGE, in gunnery, the two pieces of timber which go between the two transoms of a gun-carriage, on which the coins are placed, for elevating the piece. See CARRIAGE.

BRIDLE-_Arm Protect_, a guard used by the cavalry, which consists in having the sword-hilt above the helmet; the blade crossing the back of the head, the point of the left shoulder, and the bridle-arm; its edge directed to the left, and turned a little upwards, in order to bring the mounting in a proper direction to protect the hand.

BRIDON, or BRIDOON, the snaffle and rein of a military bridle, which acts independent of the bit and curb at the pleasure of the rider.

BRIGADE, in military affairs, implies a party or division of a body of soldiers, whether horse, foot, or artillery, under the command of a brigadier. There are, properly speaking, three sorts of brigades, viz. the brigade of an army, the brigade of a troop of horse, and the brigade of artillery. A brigade of the army is either foot or dragoons, whose exact number is not fixed, but generally consists of 3, 4, 5 or 6 regiments, or battalions: a brigade of horse may consist of 8, 10 or 12 squadrons; and that of artillery, of 6, 8 or 10 pieces of cannon, with all their appurtenances. The eldest brigade takes the right of the first line, the second of the second line, and the rest in order, the youngest always possessing the centre, unless the commander deems a different arrangement expedient; and in such case mere etiquette always bends to orders. The cavalry and artillery observe the same order.

_The Horse Artillery_ in the British service are called the _horse Brigade_; and consist of 6 troops, with their guns and stores. Their head-quarters are at Woolwich, where handsome barracks, detached from those of the royal artillery, have been erected for their accommodation.

A BRIGADE, in the French ordination, is the same as our _Regiment_; but it consists of 3 battalions, each of which is equal to one of our regiments or 1000 men; a demi brigade is half a regiment, or a French battalion.

BRIGADE-_Major_, an officer appointed by the brigadier, to assist him in the management of his brigade. The most experienced captains are generally nominated to this post; who act in the brigade as major-generals do in the armies, receiving their orders from their commanders.

BRIGADE-_Major-General_. The military commands in Great Britain being divided into districts, an office has been established for the sole transaction of brigade duties. Through this office all orders from the commander-in-chief to the generals of districts relative to corps of officers, &c. must pass. For further information on this head, see James’s _Regimental Companion_, 2d edition, vol. i. page 25.

BRIGADE _de Boulangers_, _Fr._ It was usual in the old French service, to brigade the bakers belonging to the army. Each brigade consisted of one master baker and three boys; the system is continued in the modern French army.

BRIGADIER, a military officer, whose rank is next above that of a colonel; appointed to command a corps, consisting of several battalions or regiments, called a brigade. This title in England is suppressed in time of peace, but revived in actual service in the field. Every brigadier marches at the head of his brigade upon duty. On the United States establishment, there is only one brigadier-general, who is chief in actual command; provision has been lately made by law for two more in case of war.

BRIGANDINE, or BRIGANTINE, in ancient military history, a coat of mail, or kind of defensive armor, consisting of tin.

BRINGERS-_up_, an antiquated military expression, to signify the whole rear rank of a battalion drawn up, as being the hindmost men of every file.

BRINS-_d’Est_, _Fr._ large sticks or poles resembling small pickets, with iron at each end. They are used to cross ditches, particularly in Flanders.

BRISURE, in fortification, is a line of four or five fathom, which is allowed to the curtain and orillon, to make the hollow tower, or to cover the concealed flank.

BROADSIDE, in a sea fight, implies the discharge of all the artillery on one side of a ship of war.

BROAD-SWORD, a sword with a broad blade, chiefly designed for cutting; not at present much used in the British service, except by some few regiments of cavalry and Highland infantry. Among the cavalry, this weapon has in general given place to the sabre.

The principal guards with the broad-sword are: