Lime should be slaked before being made into mortar. The lime is measured

out, deposited in a heap on a wooden "bank" or platform, and after being

well watered is covered with the correct proportion of sand. This retains

the heat and moisture necessary to thorough slaking; the time required for

this operation depends on the variety of the lime, but usually it is from a

few hours to one and a half days. If the mixing is to be done by hand the

materials must be screened to remove any unslaked lumps of lime. The

occurrence of these may be prevented by grinding the lime shortly before

use. The mass should then be well "larried," _i.e._ mixed together with the

aid of a long-handled rake called the "larry." Lime mortar should be

tempered for at least two days, roughly covered up with sacks or other

material. Before being used it must be again turned over and well mixed

together. Portland and Roman cement mortars must be mixed as required on

account of their quick-setting properties. In the case of Portland cement

mortar, a quantity sufficient only for the day's use should be "knocked

up," but with Roman cement fresh mixtures must be made several times a day,

as near as possible to the place of using. Cement mortars should never be

worked up after setting has taken place. Care should be taken to obtain the

proper consistency, which is a stiff paste. If the mortar be too thick,

extra labour is involved in its use, and much time wasted. If it be so thin

as to run easily from the trowel, a longer time is taken in setting, and

the wall is liable to settle; also there is danger that the lime or cement

will be killed by the excess of water, or at least have its binding power

affected. It is not advisable to carry out work when the temperature is

below freezing point, but in urgent cases bricklaying may be successfully

done by using unslaked lime mortar. The mortar must be prepared in small

quantities immediately before being used, so that binding action takes

place before it cools. When the wall is left at night time the top course

should be covered up to prevent the penetration of rain into the work,

which would then be destroyed by the action of frost. Bricks used during

frosty weather should be quite dry, and those that have been exposed to

rain or frost should never be employed. The question whether there is any

limit to bricklayers' work in frost is still an open one. Among the members

of the Norwegian Society of Engineers and Architects, at whose meetings the

subject has been frequently discussed, that limit is variously estimated at

between -6° to -8° Réaumur (18½° to 14° Fahr.) and -12° to -15° Réaumur (5°

above to 1¾° below zero Fahr.). It has been proved by hydraulic tests that

good bricklayers' work can be executed at the latter minimum. The

conviction is held that the variations in the opinions held on this subject

are attributable to the degree of care bestowed on the preparation of the

mortar. It is generally agreed, however, that from a practical point of

view, bricklaying should not be carried on at temperatures lower than -8°

to -10° Réaumur (14° to 9½° Fahr.), for as the thermometer falls the

expense of building is greatly increased, owing to a larger proportion of

lime being required.

For grey lime mortar the usual proportion is one part of lime to two or

three parts of sand; lias lime mortar is mixed in similar proportions,

except for work below ground, when equal quantities of lime and sand should

be used. Portland cement mortar is usually in the proportions of one to

three, or five, of sand; good results are obtained with lime mortar

fortified with cement as follows:--one part slaked lime, one part Portland

cement, and seven parts sand. Roman cement mortar should consist of one or

one and a half parts of cement to one part of sand. Selenitic lime mortar

is usually in the proportions of one to four or five, and must be mixed in

a particular manner, the lime being first ground in water in the mortar

mill, and the sand gradually added. Blue or black mortar contains equal

parts of foundry ashes and lime; but is improved by the addition of a

proportion of cement. For setting fire-bricks fire-clay is always used.

Pargetting for rendering inside chimney flues is made of one part of lime

with three parts of cow dung free from straw or litter. No efficient

substitute has been found for this mixture, which should be used fresh. A

mortar that has found approval for tall chimney shafts is composed by

grinding in a mortar-mill one part of blue lias lime with one part each of

sand and foundry ashes. In the external walls of the Albert Hall the mortar

used was one part Portland cement, one part grey Burham lime and six parts

pit sand. The lime was slaked twenty-four hours, and after being mixed

[v.04 p.0524] with the sand for ten minutes the cement was added and the

whole ground for one minute; the stuff was prepared in quantities only

sufficient for immediate use. The by-laws dated 1891, made by the London

County Council under section 16 of the Metropolis Management and Building

Acts Amendment Act 1878, require the proportions of lime mortar to be one

to three of sand or grit, and for cement mortar one to four. Clean soft

water only should be used for the purpose of making mortar.

_Grout_ is thin liquid mortar, and is legitimately used in gauged arches

and other work when fine joints are desired. In ordinary work it is

sometimes used every four or five courses to fill up any spaces that may

have been inadvertently left between the bricks. This at the best is but

doing with grout what should be done with mortar in the operation of laying

the bricks; and filling or flushing up every course with mortar requires

but little additional exertion and is far preferable. The use of grout is,

therefore, a sign of inefficient workmanship, and should not be

countenanced in good work. It is liable, moreover, to ooze out and stain

the face of the brickwork.

_Lime putty_ is pure slaked lime. It is prepared or "run," as it is termed,

in a wooden tub or bin, and should be made as long a time as possible

before being used; at least three weeks should elapse between preparation

and use.

[Illustration: FIG. 3.--Forms of Joints.]

The pointing of a wall, as previously mentioned, is done either with the

bricklaying or at the completion of the work. If the [Sidenote: Pointing.]

pointing is to be of the same mortar as the rest of the work, it would

probably greatly facilitate matters to finish off the work at one operation

with the bricklaying, but where, as in many cases, the pointing is required

to be executed in a more durable mortar, this would be done as the scaffold

is taken down at the completion of the building, the joints being raked out

by the bricklayer to a depth of ½ or ¾ in. By the latter method the whole

face of the work is kept uniform in appearance. The different forms of

joints in general use are clearly shown in fig. 3. Flat or flush joints (A)

are formed by pressing the protruding mortar back flush with the face of

the brickwork. This joint is commonly used for walls intended to be coated

with distemper or limewhite. The flat joint jointed (two forms, B and C) is

a development of the flush joint. In order to increase the density and

thereby enhance the durability of the mortar, a semicircular groove is

formed along the centre, or one on each side of the joint, with an iron

jointer and straight-edge. Another form, rarely used, is the keyed joint

shown at D, the whole width of the joint in this case being treated with

the curved key. Struck or bevelled, or weathered, joints have the upper

portion pressed back with the trowel to form a sloping surface, which

throws off the wet. The lower edge is cut off with the trowel to a straight

edge. This joint is in very common use for new work. Ignorant workmen

frequently make the slope in the opposite direction (F), thus forming a

ledge on the brick; this catches the water, which on being frozen rapidly

causes the disintegration of the upper portion of the brick and of the

joint itself. With recessed jointing, not much used, a deep shadow may be

obtained. This form of joint, illustrated in G, is open to very serious

objections, for it encourages the soaking of the brick with rain instead of

throwing off the wet, as it seems the natural function of good pointing,

and this, besides causing undue dampness in the wall, renders it liable to

damage by frost. It also leaves the arrises of the bricks unprotected and

liable to be damaged, and from its deep recessed form does not make for

stability in the work. Gauged work has very thin joints, as shown at H,

formed by dipping the side of the brick in white lime putty. The sketch I

shows a joint raked out and filled in with pointing mortar to form a flush

joint, or it may be finished in any of the preceding forms. Where the wall

is to be plastered the joints are either left open or raked out, or the

superfluous mortar may be left protruding as shown at J. By either method

an excellent key is obtained, to which the rendering firmly adheres. In

tuck pointing (K) the joints are raked out and stopped, i.e. filled in

flush with mortar coloured to match the brickwork. The face of the wall is

then rubbed over with a soft brick of the same colour, or the work may be

coloured with pigment. A narrow groove is then cut in the joints, and the

mortar allowed to set. White lime putty is next filled into the groove,

being pressed on with a jointing tool, leaving a white joint 1/8 to ¼ in.

wide, and with a projection of about 1/16 in. beyond the face of the work.

This method is not a good or a durable one, and should only be adopted in

old work when the edges of the bricks are broken or irregular. In bastard

tuck pointing (L), the ridge, instead of being in white lime putty, is

formed of the stopping mortar itself.

Footings, as will be seen on reference to fig. 1, are the wide courses of

brickwork at the base or foot of a wall. They serve to spread [Sidenote:

Footings.] the pressure over a larger area of ground, offsets 2¼ in. wide

being made on each side of the wall until a width equal to double the

thickness of the wall is reached. Thus in a wall 13½ in. (1½ bricks) thick,

this bottom course would be 2 ft. 3 in. (3 bricks) wide. It is preferable

for greater strength to double the lowest course. The foundation bed of

concrete then spreading out an additional 6 in. on each side brings the

width of the surface bearing on the ground to 3 ft. 3 in. The London

Building Act requires the projection of concrete on each side of the

brickwork to be only 4 in., but a projection of 6 in. is generally made to

allow for easy working. Footings should be built with hard bricks laid

principally as headers; stretchers, if necessary, should be placed in the

middle of the wall.

[Illustration: FIG. 4.--Diagram of Bonding.]

Bond in brickwork is the arrangement by which the bricks of every course

cover the joints of those in the course below it, and so [Sidenote:

Bonding.] tend to make the whole mass or combination of bricks act as much

together, or as dependently one upon another, as possible. The workmen

should be strictly supervised as they proceed with the work, for many

failures are due to their ignorance or carelessness in this particular. The

object of bonding will be understood by reference to fig. 4. Here it is

evident from the arrangement of the bricks that any weight placed on the

topmost brick (a) is carried down and borne alike in every course; in this

way the weight on each brick is distributed over an area increasing with

every course. But this forms a longitudinal bond only, which cannot extend

its influence beyond the width of the brick; and a wall of one brick and a

half, or two bricks, thick, built in this manner, would in effect consist

of three or four half brick thick walls acting independently of each other.

If the bricks were turned so as to show their short sides or ends in front

instead of their long ones, certainly a compact wall of a whole brick

thick, instead of half a brick, would be produced, and while the thickness

of the wall would be double, the longitudinal bond would be shortened by

one-half: a wall of any great thickness built in this manner would

necessarily be composed of so many independent one-brick walls. To produce

a transverse and yet preserve a true longitudinal bond, the bricks are laid

in a definite arrangement of stretchers and headers.

[Illustration: FIG. 5.--English Bond.

In this and following illustration of bond in brickwork the position of

bricks in the second course is indicated by dotted lines.]

In "English bond" (fig. 5), rightly considered the most perfect in use, the

bricks are laid in alternate courses of headers and stretchers, thus

combining the advantages of the two previous modes of arrangement. A

reference to fig. 5 will show how the process of bonding is pursued in a

wall one and a half bricks in thickness, and how the quoins are formed. In

walls which are a multiple of a whole brick, the appearance of the same

course is similar on the elevations of the front and back faces, but in

walls where an odd half brick must be used to make up the thickness, as is

the case in the illustration, the appearance of the opposite sides of a

course is inverted. The example illustrates the principle of English bond;

thicker walls are constructed in the same manner by an extension of the

same methods. It will be observed that portions of a brick have to be

inserted near a vertical end or a quoin, in order to start the regular

bond. These portions equal a half header in width, and are called queen

closers; they are placed next to the first header. A three-quarter brick is

obviously as available for this purpose as a header and closer combined,

but the latter method is preferred because by the use of it uniformity of

appearance is preserved, and whole bricks are retained on the returns. King

closers are used at rebated openings formed in walls in Flemish bond, and

by reason of the greater width of the back or "tail," add strength to the

work. They are cut on the splay so that the front end is half the width of

a header and one side half the length of the brick. An example of their use

will be seen in fig. 15. In walls of almost all thicknesses above 9 in.,

except in the [v.04 p.0525] English bond, to preserve the transverse and

yet not destroy the longitudinal bond, it is frequently necessary to use

half bricks. It may be taken as a general rule that a brick should never be

cut if it can be worked in whole, for a new joint is thereby created in a

construction, the difficulty of which consists in obviating the debility

arising from the constant recurrence of joints. Great insistence must be

laid on this point, especially at the junctions of walls, where the

admission of closers already constitutes a weakness which would only be

increased by the use of other bats or fragments of bricks.

[Illustration: FIG. 6.--Flemish Bond.]

Another method of bonding brickwork, instead of placing the bricks in

alternate courses of headers and stretchers, places them alternately as

headers and stretchers in the same course, the appearance of the course

being the same on each face. This is called "Flemish bond." Closers are

necessary to this variety of bond. From fig. 6 it will be seen that, owing

to the comparative weakness of the transverse tie, and the numbers of half

bricks required to be used and the thereby increased number of joints, this

bond is not so perfect nor so strong as English. The arrangements of the

face joints, however, presenting in Flemish bond a neater appearance than

in English bond, it is generally selected for the external walls of

domestic and other buildings where good effect is desirable. In buildings

erected for manufacturing and similar purposes, and in engineering works

where the greatest degree of strength and compactness is considered of the

highest importance, English bond should have the preference.

A compromise is sometimes made between the two above-mentioned bonds. For

the sake of appearance the bricks are laid to form Flemish bond on the

face, while the backing is of English bond, the object being to combine the

best features of the two bonds. Undoubtedly the result is an improvement on

Flemish bond, obviating as it does the use of bats in the interior of the

wall. This method of bonding is termed "single Flemish bond," and is shown

in fig. 7.

In stretching bond, which should only be used for walls half a brick in

thickness, all the bricks are laid as stretchers, a half brick being used

in alternate courses to start the bond. In work curved too sharply on plan

to admit of the use of stretchers, and for footings, projecting mouldings

and corbels, the bricks are all laid as headers, i.e. with their ends to

the front, and their length across the thickness of the wall. This is

termed "heading bond."

[Illustration: FIG. 7.--Single Flemish Bond.]

In thick walls, three bricks thick and upwards, a saving of labour is

effected without loss of strength, by the adoption of "herring bone" or

"diagonal bond" in the interior of the wall, the outer faces of the wall

being built in English and Flemish bond. This mode should not be had

recourse to for walls of a less thickness than 27 in., even that being

almost too thin to admit of any great advantage from it.

Hoop-iron, about 1½ in. wide and 1/16 in. thick, either galvanized or well

tarred and sanded to retard rusting, is used in order to obtain additional

longitudinal tie. The customary practice is to use one strip of iron for

each half-brick in thickness of the wall. Joints at the angles, and where

necessary in the length, are formed by bending the ends of the strips so as

to hook together. A patent stabbed iron now on the market is perforated to

provide a key for the mortar.

A difficulty often arises in bonding when facing work with bricks of a

slightly different size from those used in "backing," as it is technically

termed. As it is, of course, necessary to keep all brickwork in properly

levelled courses, a difference has to be made in the thickness of the

mortar joints. Apart from the extra labour involved, this obviously is

detrimental to the stability of the wall, and is apt to produce unequal

settlement and cracking. Too much care cannot be taken to obtain both

facing and backing bricks of equal size.

[Illustration: FIG. 8.]

Dishonest bricklayers do not hesitate, when using for the face of a wall

bricks of a quality superior to those used for the interior, to use

"snapped headers," that is cutting the heading bricks in halves, one brick

thus serving the purposes of two as regards outward appearance. This is a

most pernicious practice, unworthy of adoption by any craftsman of repute,

for a skin of brickwork 4½ in. thick is thus carried up with a straight

mortar joint behind it, the proper bonding with the back of the wall by

means of headers being destroyed.

American building acts describe the kind of bond to be used for ordinary

walls, and the kind for faced walls. Tie courses also require an extra

thickness where walls are perforated with over 30% of flues.

The importance for sanitary and other reasons of keeping walls dry is

admitted by all who have observed the deleterious action of damp upon a

building.

Walls are liable to become damp, (1) by wet rising up the wall from the

earth; (2) by water soaking down from the top of the [Sidenote: Prevention

of damp.] wall; (3) by rain being driven on to the face by wind. Dampness

from the first cause may be prevented by the introduction of damp-proof

courses or the construction of dry areas; from the second by means of a

coping of stone, cement or other non-porous material; and from the third by

covering the exterior with impervious materials or by the adoption of

hollow walls.

[Illustration: FIG. 9.]

After the footings have been laid and the wall has been brought up to not

less than 6 in. above the finished surface of the ground, and previous to

fixing the plate carrying the ground floor, there should always be

introduced a course of some damp-proof material to prevent the rise of

moisture from the soil. There are several forms of damp-proof course. A

very usual one is a double layer of roofing slates laid in neat Portland

cement (fig. 8), the joints being well lapped. A course or two of

Staffordshire blue bricks in cement is excellent where heavy weights have

to be considered. Glazed stoneware perforated slabs about 2 in. thick are

specially made for use as damp-proof courses. Asphalt (fig. 9) recently has

come into great favour with architects; a layer ½ or ¾ in. thick is a good

protection against damp, and not likely to crack should a settlement occur,

but in hot weather it is liable to squeeze out at the joints under heavy

weights. Felt covered with bitumen is an excellent substitute for asphalt,

and is not liable to crack or squeeze out. Sheet lead is efficient, but

very costly and also somewhat liable to squeezing. A damp-proof course has

been introduced consisting of a thin sheet of lead sandwiched between

layers of asphalt. Basement storeys to be kept dry require, besides the

damp-proof course horizontally in the wall, a horizontal course, usually of

asphalt, in the thickness of the floor, and also a vertical damp-proof

course from a level below that of the floor to about 6 in. above the level

of the ground, either built in the thickness of the wall or rendered on the

outside between the wall and the surrounding earth (fig. 10).

By means of dry areas or air drains (figs. 11 and 12), a hollow [v.04

p.0526] space 9 in. or more in width is formed around those portions of the

walls situated below the ground, the object being to prevent them from

coming into contact with the brickwork of the main walls and so imparting

its moisture to the building. Arrangements should be made for keeping the

area clear of vermin and for ventilating and draining it. Dry areas, being

far from sanitary, are seldom adopted now, and are being superseded by

asphalt or cement applied to the face of the wall.

[Illustration: FIG. 10.]

[Illustration: FIG. 11.]

[Illustration: FIG. 12.]

Moisture is prevented from soaking down from the top of the wall by using a

covering of some impervious material in the form of a coping. This may

consist of ordinary bricks set on edge in cement with a double course of

tiles immediately below, called a "creasing," or of specially made

non-porous coping bricks, or of stone, cast-iron, or cement sloped or

"weathered" in order to throw the rain off.

[Illustration: FIG. 13.]

The exterior of walls above the ground line may be protected by coating the

surface with cement or rough cast; or covering with slates or tiles fixed

on battens in a similar manner to those on a roof (fig.13).

The use of hollow walls in exposed positions has already been referred to.

The by-laws dated 1891, made by the London County Council under section 16

of the Metropolis Management and Buildings Acts Amendment Act 1878, require

that "every wall of a house or building shall have a damp course composed

of materials impervious to moisture approved by the district surveyor,

extending throughout its whole thickness at the level of not less than 6

in. below the level of the lowest floor. Every external wall or enclosing

wall of habitable rooms or their appurtenances or cellars which abuts

against the earth shall be protected by materials impervious to moisture to

the satisfaction of the district surveyor..." "The top of every party-wall

and parapet-wall shall be finished with one course of hard, well-burnt

bricks set on edge, in cement, or by a coping of any other waterproof and

fire-resisting material, properly secured."

Arches are constructions built of wedge-shaped blocks, which by reason of

their shape give support one to another, and to the [Sidenote: Arches.]

super-imposed weight, the resulting load being transmitted through the

blocks to the abutments upon which the ends of the arch rest. An arch

should be composed of such materials and designed of such dimensions as to

enable it to retain its proper shape and resist the crushing strain imposed

upon it. The abutments also must be strong enough to take safely the thrust

of the weighted arch, as the slightest movement in these supports will

cause deflection and failure. The outward thrust of an arch decreases as it

approaches the semicircular form, but the somewhat prevalent idea that in

the latter form no thrusting takes place is at variance with fact.

[Illustration: FIG. 14.]

Arches in brickwork may be classed under three heads: plain arches,

rough-cut and gauged. Plain arches are built of uncut bricks, and since the

difference between the outer and inner periphery of the arch requires the

parts of which an arch is made up to be wedge-formed, which an ordinary

brick is not, the difference must be made in mortar, with the result that

the joints become wedge-shaped. This obviously gives an objectionable

inconsistency of material in the arch, and for this reason to obtain

greatest strength it is advisable to build these arches in independent

rings of half-brick thickness. The undermost rings should have thin joints,

those of each succeeding ring being slightly thickened. This prevents the

lowest ring from settling while those above remain in position, which would

cause an ugly fissure. In work of large span bonding blocks or "lacing

courses" should be built into the arch, set in cement and running through

its thickness at intervals, care being taken to introduce the lacing course

at a place where the joints of the various rings coincide. Stone blocks in

the shape of a voussoir (fig. 14) may be used instead. Except for these

lacing courses hydraulic lime mortar should be used for large arches, on

account of its slightly accommodating nature.

Rough-cut arches are those in which the bricks are roughly cut with an axe

to a wedge form; they are used over openings, such as doors and windows,

where a strong arch of neat appearance is desired. The joints are usually

made equal in width to those of the ordinary brickwork. Gauged arches are

composed of specially made soft bricks, which are cut and rubbed to gauges

or templates so as to form perfectly fitting voussoirs. Gauging is, of

course, equally applicable to arches and walling, as it means no more than

bringing every brick exactly to a certain form by cutting and rubbing.

Gauged brickwork is set in lime putty instead of common mortar; the

finished joints should not be more than 1/32 in. wide. To give stability

the sides of the voussoirs are gauged out hollow and grouted in Portland

cement, thus connecting each brick with the next by a joggle joint. Gauged

arches, being for the most part but a half-brick in thickness on the soffit

and not being tied by a bond to anything behind them--for behind them is

the lintel with rough discharging arch over, supporting the remaining width

of the wall--require to be executed with great care and nicety. It is a

common fault with workmen to rub the bricks thinner behind than before to

lessen the labour required to obtain a very fine face joint. This practice

tends to make the work bulge outwards; it should rather be inverted if it

be done at all, though the best work is that in which the bricks are gauged

to exactly the same thickness at the back as at the front. The same fault

occurs when a gauged arch is inserted in an old wall, on account of the

difficulty of filling up with cement the space behind the bricks.

The bond of an arch obtains its name from the arrangement of headers and

stretchers on its soffit. The under side of an arch built in English bond,

therefore, will show the same arrangement as the face of a wall built in

English bond. If the arch is in Flemish the soffit presents the same

appearance as the elevation of a wall built in that bond.

It is generally held that the building of wood into brickwork [Sidenote:

Plates.] should as far as is possible be avoided. Wall plates of wood are,

however, necessary where wood joists are used, and where these plates may

not be supported on corbels of projecting brickwork or iron they must be

let flush into the wall, taking the place of a course of bricks. They form

a uniform bed for the joists, to which easy fixing is obtained. The various

modes adopted for resting and fixing the ends of joists on walls are

treated in the article CARPENTRY.

[Illustration: FIG. 15.]

Lintels, which may be of iron, steel, plain or reinforced concrete, or

stone, are used over square-headed openings instead of or in conjunction

with arches. They are useful to preserve the square form and receive the

joiners' fittings, but except when made of steel or of concrete reinforced

with steel bars, they should have relieving arches turned immediately over

them (Fig.15).

"Fixing bricks" were formerly of wood of the same size as the ordinary

brick, and built into the wall as required for fixing joinery. Owing to

their liability to shrinkage and decay, their use is now practically

abandoned, their place being taken by bricks of coke-breeze concrete, which

do not shrink or rot and hold fast nails or screws driven into them.

Another method often adopted for [v.04 p.0527] providing a fixing for

joinery is to build in wood slips the thickness of a joint and 4½ in. wide.

When suitable provision for fixing has not been made, wood plugs are driven

into the joints of the bricks. Great care must be taken in driving these in

the joints of reveals or at the corners of walls, or damage may be done.

The name "brick-ashlar" is given to walls faced with ashlar stonework

backed in with brickwork. Such constructions are liable in an aggravated

degree to the unequal settling and its attendant evils pointed out as

existing in walls built with different qualities of bricks. The outer face

is composed of unyielding stone with few and very thin joints, which

perhaps do not occupy more than a hundredth part of its height, while the

back is built up of bricks with about one-eighth its height composed of

mortar joints, that is, of a material that by its nature and manner of

application must both shrink in drying and yield to pressure. To obviate

this tendency to settle and thus cause the bulging of the face or failure

of the wall, the mortar used should be composed of Portland cement and sand

with a large proportion of the former, and worked as stiff as it

conveniently can be. In building such work the stones should be in height

equal to an exact number of brick courses. It is a common practice in

erecting buildings with a facing of Kentish rag rubble to back up the

stonework with bricks. Owing to the great irregularity of the stones, great

difficulty is experienced in obtaining proper bond between the two

materials. Through bonding stones or headers should be frequently built in,

and the whole of the work executed in cement mortar to ensure stability.

Not the least important part of the bricklayer's art is the formation of

chimney and other flues. Considerable skill is required in [Sidenote:

Chimneys and flues.] gathering-over properly above the fireplace so as to

conduct the smoke into the smaller flue, which itself requires to be built

with precision, so that its capacity may not vary in different parts. Bends

must be made in gradual curves so as to offer the least possible resistance

to the up-draught, and at least one bend of not less than 60° should be

formed in each flue to intercept down-draughts. Every fireplace must have a

separate flue. The collection of a number of flues into a "stack" is

economical, and tends to increase the efficiency of the flues, the heat

from one flue assisting the up-draught in those adjoining it. It is also

desirable from an aesthetic point of view, for a number of single flue

chimneys sticking up from various parts of the roof would appear most

unsightly. The architects of the Elizabethan and later periods were masters

of this difficult art of treating a stack or stacks as an architectural

feature. The shaft should be carried well above the roof, higher, if

possible, than adjacent buildings, which are apt to cause down-draught and

make the chimney smoke. When this is found impossible, one of the many

forms of patent chimney-pots or revolving cowls must be adopted. Each flue

must be separated by smoke-proof "withes" or divisions, usually half a

brick in thickness; connexion between them causes smoky chimneys. The size

of the flue for an ordinary grate is 14×9 in.; for a kitchen stove 14×14

in. The outer wall of a chimney stack may with advantage be made 9 in.

thick. Fireclay tubes, rectangular or circular in transverse section, are

largely used in place of the pargetting; although more expensive than the

latter they have the advantage in point of cleanliness and durability.

Fireplaces generally require more depth than can be provided in the

thickness of the wall, and therefore necessitate a projection to contain

the fireplace and flues, called the "chimney breast." Sometimes, especially

when the wall is an external one, the projection may be made on the back,

thus allowing a flush wall in the room and giving more space and a more

conveniently-shaped room. The projection on the outside face of the wall

may be treated as an ornamental feature. The fireplace opening is covered

by a brick relieving arch, which is fortified by wrought-iron bar from ½ to

¾ in. thick and 2 to 3 in. wide. It is usually bent to a "camber," and the

brick arch built upon it naturally takes the same curve. Each end is

"caulked," that is, split longitudinally and turned up and down. The

interior of a chimney breast behind the stove should always be filled in

solid with concrete or brickwork. The flooring in the chimney opening is

called the "hearth"; the back hearth covers the space between the jambs of

the chimney breast, and the front hearth rests upon the brick "trimmer

arch" designed to support it. The hearth is now often formed in solid

concrete, supported on the brick wall and fillets fixed to the floor

joists, without any trimmer arch and finished in neat cement or glazed

tiles instead of stone slabs.

Tall furnace chimneys should stand as separate constructions, unconnected

with other buildings. If it is necessary to bring other work close up, a

straight joint should be used. The shaft of the chimney will be built

"overhand," the men working from the inside. Lime mortar is used, cement

being too rigid to allow the chimney to rock in the wind. Not more than 3

ft. in height should be erected in one day, the work of necessity being

done in small portions to allow the mortar to set before it is required to

sustain much weight. The bond usually adopted is one course of headers to

four of stretchers. Scaffolding is sometimes erected outside for a height

of 25 or 30 ft., to facilitate better pointing, especially where the

chimney is in a prominent position. The brickwork at the top must,

according to the London Building Act, be 9 in. thick (it is better 14 in.

in shafts over 100 ft. high), increasing half a brick in thickness for

every additional 20 ft. measured downwards. "The shaft shall taper

gradually from the base to the top at the rate of at least 2½ in. in 10 ft.

of height. The width of the base of the shaft if square shall be at least

one-tenth of the proposed height of the shaft, or if round or any other

shape, then one-twelfth of the height. Firebricks built inside the lower

portion of the shaft shall be provided, as additional to and independent of

the prescribed thickness of brickwork, and shall not be bonded therewith."

The firebrick lining should be carried up from about 25 ft. for ordinary

temperatures to double that height for very great ones, a space of 1½ to 3

in. being kept between the lining and the main wall. The lining itself is

usually 4½ in. thick. The cap is usually of cast iron or terra-cotta

strengthened with iron bolts and straps, and sometimes of stone, but the

difficulty of properly fixing this latter material causes it to be

neglected in favour of one of the former. (See a paper by F.J. Bancroft on

"Chimney Construction," which contains a tabulated description of nearly

sixty shafts, _Proc. Civ. and Mech. Eng. Soc._, December 1883.)

The work of laying bricks or tiles as paving falls to the lot of the

bricklayer. Paving formed of ordinary bricks laid flat or on their

[Sidenote: Brick paving.] edges was once in general use, but is now almost

abandoned in favour of floors of special tiles or cement paving, the latter

being practically non-porous and therefore more sanitary and cleaner.

Special bricks of extremely hard texture are made for stable and similar

paving, having grooves worked on the face to assist drainage and afford

good foothold. A bed of concrete 6 in. thick is usually provided under

paving, or when the bricks are placed on edge the concrete for external

paving may be omitted and the bricks bedded in sand, the ground being

previously well rammed. The side joints of the bricks are grouted in with

lime or cement. Dutch clinkers are small, hard paving bricks burned at a

high temperature and of a light yellow colour; they are 6 in. long, 3 in.

wide, 1½ in. thick. A variety of paving tile called "oven tiles" is of

similar material to the ordinary red brick, and in size is 10 or 12 in.

square and 1 to 2 in. thick. An immense variety of ornamental paving and

walling tiles is now manufactured of different colours, sizes and shapes,

and the use of these for lining sculleries, lavatories, bathrooms,

provision shops, &c., makes for cleanliness and improved sanitary

conditions. Besides, however, being put to these uses, tiles are often used

in the ornamentation of buildings, externally as well as internally.

Mosaic work is composed of small pieces of marble, stone, glass or pottery,

laid as paving or wall lining, usually in some ornamental pattern or

design. A firm bed of concrete is required, the pieces of [v.04 p.0528]

material being fixed in a float of cement about half or three-quarters of

an inch thick. Roman mosaic is formed with cubes of marble of various

colours pressed into the float. A less costly paving may be obtained by

strewing irregularly-shaped marble chips over the floated surface: these

are pressed into the cement with a plasterer's hand float, and the whole is

then rolled with an iron roller. This is called "terazzo mosaic." In either

the Roman or terazzo method any patterns or designs that are introduced are

first worked in position, the ground-work being filled in afterwards. For

the use of cement for paving see PLASTER.

The principal publications on brickwork are as follows:--Rivington, _Notes

on Building Construction_, vols. i. ii. iii.; Col. H.E. Seddon, _Aide

Memoir_, vol. ii.; _Specification_; J.P. Allen, _Building Construction_;

F.E. Kidder, _Building Construction and Superintendence_, part i. (1903);

Longmans & Green, _Building Construction_; E. Dobson, _Bricks and Tiles_;

Henry Adams, _Building Construction_; C.F. Mitchell, _Building

Construction_, vols. i. ii.; E. Street, _Brick and Marble Architecture in

Italy_.

(J. BT.)

BRICOLE (a French word of unknown origin), a military engine for casting

heavy stones; also a term in tennis for a sidestroke rebounding off the

wall of the court, corrupted into "brickwall" from a supposed reference to

the wall, and in billiards for a stroke off the cushion to make a cannon or

hazard.

BRIDAINE (or BRYDAYNE), JACQUES (1701-1767), French Roman Catholic

preacher, was born at Chuslan in the department of Gard on the 21st of

March 1701. He was educated at Avignon, first in the Jesuit college and

afterwards at the Sulpician seminary of St Charles. Soon after his

ordination to the priesthood in 1725, he joined the _Missions Royales_,

organized to bring back to the Catholíc faith the Protestants of France. He

gained their good-will and made many converts; and for over forty years he

visited as a missionary preacher almost every town of central and southern

France. In Paris, in 1744, his sermons created a deep impression by their

eloquence and sincerity. He died at Roquemaure, near Avignon, on the 22nd

of December 1767. He was the author of _Cantiques spirituels_ (Montpelier,

1748, frequently reprinted, in use in most French churches); his sermons

were published in 5 vols. at Avignon in 1823 (ed. Paris, 1861).

See Abbé G. Carron, _Le Modèle des prêtres_ (1803).

BRIDE (a common Teutonic word, e.g. Goth. _bruths_, O.Eng. _bryd_, O.H.Ger.

_prût_, Mod. Ger. _Braut_, Dut. _bruid_, possibly derived from the root

_bru-_, cook, brew; from the med. latinized form _bruta_, in the sense of

daughter-in-law, is derived the Fr. _bru_), the term used of a woman on her

wedding-day, and applicable during the first year of wifehood. It appears

in combination with many words, some of them obsolete. Thus "bridegroom" is

the newly married man, and "bride-bell," "bride-banquet" are old

equivalents of wedding-bells, wedding-breakfast. "Bridal" (from

_Bride-ale_), originally the wedding-feast itself, has grown into a general

descriptive adjective, e.g. the _bridal_ party, the _bridal_ ceremony. The

_bride-cake_ had its origin in the Roman _confarreatio_, a form of

marriage, the essential features of which were the eating by the couple of

a cake made of salt, water and flour, and the holding by the bride of three

wheat-ears, symbolical of plenty. Under Tiberius the cake-eating fell into

disuse, but the wheat ears survived. In the middle ages they were either

worn or carried by the bride. Eventually it became the custom for the young

girls to assemble outside the church porch and throw grains of wheat over

the bride, and afterwards a scramble for the grains took place. In time the

wheat-grains came to be cooked into thin dry biscuits, which were broken

over the bride's head, as is the custom in Scotland to-day, an oatmeal cake

being used. In Elizabeth's reign these biscuits began to take the form of

small rectangular cakes made of eggs, milk, sugar, currants and spices.

Every wedding guest had one at least, and the whole collection were thrown

at the bride the instant she crossed the threshold. Those which lighted on

her head or shoulders were most prized by the scramblers. At last these

cakes became amalgamated into a large one which took on its full glories of

almond paste and ornaments during Charles II.'s time. But even to-day in

rural parishes, e.g. north Notts, wheat is thrown over the bridal couple

with the cry "Bread for life and pudding for ever," expressive of a wish

that the newly wed may be always affluent. The throwing of rice, a very

ancient custom but one later than the wheat, is symbolical of the wish that

the bridal may be fruitful. The _bride-cup_ was the bowl or loving-cup in

which the bridegroom pledged the bride, and she him. The custom of breaking

this wine-cup, after the bridal couple had drained its contents, is common

to both the Jews and the members of the Greek Church. The former dash it

against the wall or on the ground, the latter tread it under foot. The

phrase "bride-cup" was also sometimes used of the bowl of spiced wine

prepared at night for the bridal couple. _Bride-favours_, anciently called

bride-lace, were at first pieces of gold, silk or other lace, used to bind

up the sprigs of rosemary formerly worn at weddings. These took later the

form of bunches of ribbons, which were at last metamorphosed into rosettes.

_Bridegroom-men_ and _bridesmaids_ had formerly important duties. The men

were called bride-knights, and represented a survival of the primitive days

of marriage by capture, when a man called his friends in to assist to

"lift" the bride. Bridesmaids were usual in Saxon England. The senior of

them had personally to attend the bride for some days before the wedding.

The making of the bridal wreath, the decoration of the tables for the

wedding feast, the dressing of the bride, were among her special tasks. In

the same way the senior groomsman (the _best man_) was the personal

attendant of the husband. The _bride-wain_, the wagon in which the bride

was driven to her new home, gave its name to the weddings of any poor

deserving couple, who drove a "wain" round the village, collecting small

sums of money or articles of furniture towards their housekeeping. These

were called bidding-weddings, or bid-ales, which were in the nature of

"benefit" feasts. So general is still the custom of "bidding-weddings" in

Wales, that printers usually keep the form of invitation in type. Sometimes

as many as six hundred couples will walk in the bridal procession. The

_bride's wreath_ is a Christian substitute for the gilt coronet all Jewish

brides wore. The crowning of the bride is still observed by the Russians,

and the Calvinists of Holland and Switzerland. The wearing of orange

blossoms is said to have started with the Saracens, who regarded them as

emblems of fecundity. It was introduced into Europe by the Crusaders. The

_bride's veil_ is the modern form of the _flammeum_ or large yellow veil

which completely enveloped the Greek and Roman brides during the ceremony.

Such a covering is still in use among the Jews and the Persians.

See Brand, _Antiquities of Great Britain_ (Hazlitt's ed., 1905); Rev J.

Edward Vaux, _Church Folklore_ (1894).

BRIDEWELL, a district of London between Fleet Street and the Thames, so

called from the well of St Bride or St Bridget close by. From William the

Conqueror's time, a castle or Norman tower, long the occasional residence

of the kings of England, stood there by the Fleet ditch. Henry VIII., Stow

says, built there "a stately and beautiful house," specially for the

housing of the emperor Charles V. and his suite in 1525. During the hearing

of the divorce suit by the Cardinals at Blackfriars, Henry and Catharine of

Aragon lived there. In 1553 Edward VI. made it over to the city as a

penitentiary, a house of correction for vagabonds and loose women; and it

was formally taken possession of by the lord mayor and corporation in 1555.

The greater part of the building was destroyed in the Great Fire of 1666.

New Bridewell, built in 1829, was pulled down in 1864. The term has become

a synonym for any reformatory.

BRIDGE, a game of cards, developed out of the game of whist. The country of

its origin is unknown. A similar game is said to have been played in

Denmark in the middle of the 19th century. A game in all respects the same

as bridge, except that in "no trumps" each trick counted ten instead of

twelve, was played in England about 1884 under the name of Dutch whist.

Some connect it with Turkey and Egypt under the name of "Khedive," or with

a Russian game called "Yeralash." It was in Turkey that it first won a

share of popular favour. Under the synonyms of "Biritch," "Bridge," or

"Russian whist," it found its way to the London clubs about 1894, from

which date its popularity rapidly increased.

_Ordinary Bridge._--Bridge, in its ordinary form, differs from [v.04

p.0529] whist in the following respects:--Although there are four players,

yet in each hand the partner of the dealer takes no part in the play of

that particular hand. After the first lead his cards are placed on the

table exposed, and are played by the dealer as at dummy whist; nevertheless

the dealer's partner is interested in the result of the hand equally with

the dealer. The trump suit is not determined by the last card dealt, but is

selected by the dealer or his partner without consultation, the former

having the first option. It is further open to them to play without a trump

suit. The value of tricks and honours varies with the suit declared as

trumps. Honours are reckoned differently from whist, and on a scale which

is somewhat involved. The score for honours does not count towards winning

or losing the rubber, but is added afterwards to the trick score in order

to determine the value of the rubber. There are also scores for holding no

trumps ("chicane"), and for winning all the tricks or all but one ("slam").

The score has to be kept on paper. It is usual for the scoring block to

have two vertical columns divided halfway by a horizontal line. The left

column is for the scorers' side, and the right for the opponents'. Honours

are scored above the horizontal line, and tricks below. The drawback to

this arrangement is that, since the scores for each hand are not kept

separately, it is generally impossible to trace an error in the score

without going through the whole series of hands. A better plan, it seems,

is to have four columns ruled, the inner two being assigned to tricks, the

outer ones to honours. By this method a line can be reserved for each hand,

and any discrepancy in the scores at once rectified.

The Portland Club, London, drew up a code of laws in 1895, and this code,

with a few amendments, was in July 1895 adopted by a joint committee of the

Turf and Portland Clubs. A revised code came into force in January 1905,

the provisions of which are here summarized.

Each trick above 6 counts 2 points in a spade declaration, 4 in a club, 6

in a diamond, 8 in a heart, 12 in a no-trump declaration. The game consists

of 30 points made by tricks alone. When one side has won two games the

rubber is ended. The winners are entitled to add 100 points to their score.

Honours consist of ace, king, queen, knave, ten, in a suit declaration. If

a player and his partner conjointly hold 3 (or "simple") honours they score

twice the value of a trick; if 4 honours, 4 times; if 5 honours, 5 times.

If a player in his own hand hold 4 honours he is entitled to score 4

honours in addition to the score for conjoint honours; thus, if one player

hold 4 honours and his partner the other their total score is 9 by honours.

Similarly if a player hold 5 honours in his own hand he is entitled to

score 10 by honours. If in a no-trump hand the partners conjointly hold 3

aces, they score 30 for honours; if 4 aces, 40 for honours. 4 aces in 1

hand count 100. On the same footing as the score for honours are the

following: _chicane_, if a player hold no trump, in amount equal to simple

honours; _grand slam_, if one side win all the tricks, 40 points; _little

slam_, if they win 12 tricks, 20 points. At the end of the rubber the total

scores, whether made by tricks, honours, chicane, slam, or rubber points,

are added together, and the difference between the two totals is the number

of points won.

At the opening of play, partners are arranged and the cards are shuffled,

cut and dealt (the last card not being turned) as at whist; but the dealer

cannot lose the deal by misdealing. After the deal is completed, the dealer

makes the trump or no-trump (_sans atout_) declaration, or passes the

choice to his partner without remark. If the dealer's partner make the

declaration out of his turn, the adversary on the dealer's left may,

without consultation, claim a fresh deal. If an adversary make a

declaration, the dealer may claim a fresh deal or disregard the

declaration. Then after the declaration, either adversary may double, the

leader having first option. The effect of doubling is that each trick is

worth twice as many points as before; but the scores for honours, chicane

and slam are unaltered. If a declaration is doubled, the dealer and his

partner have the right of redoubling, thus making each trick worth four

times as much as at first. The declarer has the first option. The other

side can again redouble, and so on; but the value of a trick is limited to

100 points. In the play of the hand the laws are nearly the same as the

laws of whist, except that the dealer may expose his cards and lead out of

turn without penalty; after the second hand has played, however, he can

only correct this lead out of turn with the permission of the adversaries.

Dummy cannot revoke. The dealer's partner may take no part in the play of

the hand beyond guarding the dealer against revoking.

_Advice to Players._--In the choice of a suit two objects are to be aimed

at: first, to select the suit in which the combined forces have the best

chance of making tricks; secondly, to select the trump so that the value of

the suit agrees with the character of the hand, _i.e._ a suit of high value

when the hands are strong and of low value when very weak. As the deal is a

great advantage it generally happens that a high value is to be aimed at,

but occasionally a low value is desirable. The task of selection should

fall to the hand which has the most distinctive features, that is, either

the longest suit or unusual strength or weakness. No consultation being

allowed, the dealer must assume only an average amount of variation from

the normal in his partner's hand. If his own hand has distinctive features

beyond the average, he should name the trump suit himself, otherwise pass

it to his partner. It may here be stated what is the average in these

respects.

As regards the length of a suit, a player's long suit is rather more likely

to be fewer than five than over five. If the dealer has in his hand a suit

of five cards including two honours, it is probable that he has a better

suit to make trumps than dummy; if the suit is in hearts, and the dealer

has a fair hand, he ought to name the trump. As regards strength, the

average hand would contain ace, king, queen, knave and ten, or equivalent

strength. Hands stronger or weaker than this by the value of a king or less

may be described as featureless. If the dealer's hand is a king over the

average, it is more likely than not that his partner will either hold a

stronger hand, or will hold such a weak hand as will counteract the

player's strength. The dealer would not generally with such a hand declare

no trump, especially as by making a no-trump declaration the dealer

forfeits the advantage of holding the long trumps.

_Declarations by Dealer._--In calculating the strength of a hand a knave is

worth two tens, a queen is worth two knaves, a king is worth a queen and

knave together, and an ace is worth a king and queen together. A king

unguarded is worth less than a queen guarded; a queen is not fully guarded

unless accompanied by three more cards; if guarded by one small card it is

worth a knave guarded. An ace also loses in value by being sole.

A hand to be strong enough for a no-trump declaration should be a king and

ten above the average with all the honours guarded and all the suits

protected. It must be a king and knave or two queens above the average if

there is protection in three suits. It must be an ace or a king and queen

above the average if only two suits are protected. An established black

suit of six or more cards with a guarded king as card of entry is good

enough for no trumps. With three aces no trumps can be declared. Without an

ace, four kings, two queens and a knave are required in order to justify

the declaration. When the dealer has a choice of declarations, a sound

heart make is to be preferred to a doubtful no-trump. Four honours in

hearts are to be preferred to any but a very strong no-trump declaration;

but four aces counting 100 points constitute a no-trump declaration without

exception.

Six hearts should be made trumps and five with two honours unless the hand

is very weak; five hearts with one honour or four hearts with three honours

should be declared if the hand is nearly strong enough for no trumps, also

if the hand is very irregular with one suit missing or five of a black

suit. Six diamonds with one honour, five with three honours or four all

honours should be declared; weaker diamonds should be declared if the suits

are irregular, especially if blank in hearts. Six clubs with three honours

or five with four honours should be declared. Spades are practically only

declared with a weak hand; with only a king in the hand a suit of five

spades should be declared as a defensive measure. With nothing above a ten

a suit of two or three spades can be declared, though even with the weakest

hands a suit of five clubs or of six red cards will probably prove less

expensive.

_Declarations by Dummy._--From the fact that the call has been passed, the

dealer's partner must credit the dealer with less than average strength as

regards the rank of his cards, and probably a slightly increased number of

black cards; he must therefore be more backward in making a high

declaration whenever he can make a sound declaration of less value. On the

other hand, he has not the option of passing the declaration, and may be

driven to declare on less strength because the only alternative is a short

suit of spades. For example, with the hand: Hearts, ace, kv. 2; diamonds,

qn. 9, 7, 6, 3; clubs, kg. 10, 4; spades, 9, 2, the chances are in the

dealer's favour with five trumps, but decidedly against with only two, and

the diamond declaration is to be preferred to the spade. Still, a hand may

be so weak that spades should be declared with two or less, but five clubs

or six diamonds would be preferable with the weakest of hands.

[v.04 p.0530] _Declarations to the Score._--When one's score is over

twenty, club declarations should be made more frequently by the dealer.

Spades should be declared with six at the score of twenty-six and with five

at twenty-eight. When much behind in the score a risky no-trumper such as

one with an established suit of seven or eight cards without a card of

entry, may be declared.

Declaring to the score is often overdone; an ordinary weak no-trump

declaration carries with it small chances of three by tricks unless dummy

holds a no-trump hand.

_Doubling._--Practically the leader only doubles a no-trump declaration

when he holds what is probably an established suit of seven cards or a suit

which can be established with the loss of one trick and he has good cards

of re-entry. Seven cards of a suit including the ace, king and queen make

sound double without any other card of value in the hand, or six cards

including king, queen and knave with two aces in other suits.

Doubling by the third hand is universally understood to mean that the

player has a very strong suit which he can establish. In response to the

double his partner, according to different conventions, leads either a

heart or his own shortest suit as the one most likely to be the third

player's strongest. Under the short suit convention, if the doubler holds

six of a suit headed by the ace, king and queen, it is about an even chance

that his suit will be selected; he should not double with less strength.

Under the heart convention it is not necessary to have such great strength;

with a strong suit of six hearts and good cards of re-entry, enough tricks

will be saved to compensate for the doubled value. A player should

ascertain the convention followed before beginning to play.

Before doubling a suit declaration a player should feel almost certain that

he is as strong as the declarer. The minimum strength to justify the

declaration is generally five trumps, but it may have been made on six. If,

then, a player holds six trumps with an average hand as regards the rank of

his cards, or five trumps with a hand of no-trump strength, it is highly

probable that he is as strong as the declarer. It must be further taken

into account that the act of doubling gives much valuable information to

the dealer, who would otherwise play with the expectation of finding the

trumps evenly distributed; this is counterbalanced when the doubler is on

the left of the declaring hand by the intimation given to his partner to

lead trumps through the strong hand. In this position, then, the player

should double with the strength stated above. When on the declarer's right,

the player should hold much greater strength unless his hand is free from

tenaces. When a spade declaration has been made by dummy, one trump less is

necessary and the doubler need not be on the declarer's left. A spade

declaration by the dealer can be doubled with even less strength. A

declaration can be rather more freely doubled when a single trick undoubled

will take the dealer out, but even in this position the player must be

cautious of informing the dealer that there is a strong hand against him.

_Redoubling._--When a declaration has been doubled, the declarer knows the

minimum that he will find against him; he must be prepared to find

occasionally strength against him considerably exceeding this minimum.

Except in the case of a spade declaration, cases in which redoubling is

justifiable are very rare.

_The Play of the Hand._--In a no-trump declaration the main object is to

bring in a long suit. In selecting the suit to establish, the following are

favourable conditions:--One hand should hold at least five cards of the

suit. The two hands, unless with a sequence of high cards, should hold

between them eight cards of the suit, so as to render it probable that the

suit will be established in three rounds. The hand which contains the

strong suit should be sufficiently strong in cards of re-entry. The suit

should not be so full of possible tenaces as to make it disadvantageous to

open it. As regards the play of the cards in a suit, it is not the object

to make tricks early, but to make all possible tricks. Deep finesses should

be made when there is no other way of stealing a trick. Tricks may be given

away, if by so doing a favourable opening can be made for a finesse. When,

however, it is doubtful with which hand the finesse should be made, it is

better to leave it as late as possible, since the card to be finessed

against may fall, or an adversary may fail, thus disclosing the suit. It is

in general unsound to finesse against a card that must be unguarded. From a

hand short in cards of re-entry, winning cards should not be led out so as

to exhaust the suit from the partner's hand. Even a trick should sometimes

be given away. For instance, if one hand holds seven cards headed by ace,

king, and the other hand hold's only two of the suit, although there is a

fair chance of making seven tricks in the suit, it would often be right to

give the first trick to the adversaries. When one of the adversaries has

shown a long suit, it is frequently possible to prevent its being brought

in by a device, such as holding up a winning card, until the suit is

exhausted from his partner's hand, or playing in other suits so as to give

the player the lead whilst his partner his a card of his suit to return,

and to give the latter the lead when he has no card to return. The dealer

should give as little information as possible as to what he holds in his

own hand, playing frequent false cards. Usually he should play the higher

or highest of a sequence; still, there are positions in which playing the

higher gives more information than the lower; a strict adherence to a rule

in itself assists the adversaries.

With a suit declaration, if there is no chance of letting the weak hand

make a trump by ruffing, it will generally be the dealer's aim to discard

the losing cards in the declaring hand either to high cards or to the cards

of an established suit in the other hand, sometimes after the adverse

trumps have been taken out, but often before, there being no time for

drawing trumps. With no card of any value in a suit in one hand, the lead

should come from that hand, but it is better, if possible, to let the

adversaries open the suit. It is generally useless to lead a moderately

high card from the weaker hand in order to finesse it, when holding no

cards in sequence with it in either hand. Sometimes (especially in

no-trumps) it is the better play to make the weak hand third player. For

instance, with king, 8, 7, 5, 2 in one hand, knave, 4 in the other, the

best way of opening is from the hand that holds five cards.

In a no-trump declaration the opponents of the dealer should endeavour to

find the longest suit in the two hands, or the one most easily established.

With this object the leader should open his best suit. If his partner next

obtains the lead he ought to return the suit, unless he himself has a suit

which he considers better, having due regard to the fact that the first

suit is already partially established. The opponents should employ the same

tactics as the dealer to prevent the latter from bringing in a long suit;

they can use them with special effect when the long suit is in the exposed

hand.

Against no-trumps the leader should not play his winning cards unless he

has a good chance of clearing the suit without help from his partner; in

most cases it is advisable to give away the first trick, especially if he

has no card of re-entry, in order that his partner on gaining the lead may

have a card of the suit to return; but holding ace, king and queen, or ace,

king with seven in the suit, or ace, king, knave, ten with six, the player

may lead out his best. With three honours any two of which are in sequence

(not to the ace) the player should lead the higher of the sequence. He

should lead his highest card from queen, knave, ten; from queen, knave,

nine; from knave, ten, nine; knave, ten, eight, and ten, nine, eight. In

other cases the player should lead a small card; according to the usual

convention, the fourth best. His partner, and also the dealer, can credit

him with three cards higher than the card led, and can often place the

cards of the suit: for instance, the seven is led, dummy holds queen and

eight, playing the queen, the third player holds the nine and smaller

cards; the unseen cards higher than the seven are ace, king, knave and ten

of which the leader must hold three; he cannot hold both knave and ten or

he would have led the knave; he must therefore hold the ace, king and

either knave or ten. The "eleven" rule is as follows: the number of pips in

the card led subtracted from eleven (11-7=4 in the case stated) gives the

number of cards higher than the one led not in the leader's hand; the three

cards seen (queen, nine and eight) leave one for the dealer to hold. The

mental process is no shorter than assigning three out of the unseen cards

to the leader, and by not noting the unseen cards much valuable information

may be missed, as in the illustrative case given.

With a suit declared the best opening lead is a singleton, failing which a

lead from a strong sequence. A lead from a tenace or a guarded king or

queen is to be avoided. Two small cards may be led from, though the lead is

objected to by some. A suit of three small cards of no great strength

should not be opened. In cases of doubt preference should be given to

hearts and to a less extent to diamonds.

To lead up to dummy's weak suits is a valuable rule. The converse, to lead

through strength, must be used with caution, and does not apply to no-trump

declarations. It is not advisable to adopt any of the recent whist methods

of giving information. It is clear that, if the adversaries signal, the

dealer's hand alone is a secret, and he, in addition to his natural

advantage, has the further advantage of better information than either of

the adversaries. The following signals are however, used, and are of great

trick-making value: playing an unnecessarily high card, whether to one's

partner's suit or in discarding in a no-trump declaration, indicates

strength in the suit; in a suit declaration a similar method of play

indicates two only of the suit and a desire to ruff,--it is best used in

the case of a king led by one's partner.

The highest of a sequence led through dummy will frequently tell the third

player that he has a good finesse. The lowest of a sequence led through the

dealer will sometimes explain the position to the third player, at the same

time keeping the dealer in the dark.

When on dummy's left it is futile to finesse against a card not in dummy's

hand. But with ace and knave, if dummy has either king or queen, the knave

should usually be played, partly because the other high card may be in the

leader's hand, partly because, if the finesse fails, the player may still

hold a tenace over dummy. When a player is with any chance of success

trying to establish his long suit, he should keep every card of it if

possible, whether it is a suit already opened or a suit which he wishes his

partner to lead; when, however, the main object of the hand is to establish

one's partner's suit, it is not necessary for a player to keep his own long

suit, and he should pay attention to guarding the other suits. In some

circles a discard from a suit is always understood to indicate strength in

the suit; this convention, while it makes the game easier for inferior

players, frequently causes the player to throw away one of his most

valuable cards.

_Playing to the Score._--At the beginning of the hand the chances are so

great against any particular result, that at the score of love-all the

advantage of getting to any particular score has no appreciable [v.04

p.0531] effect in determining the choice of suit. In the play of the hand,

the advantage of getting to certain points should be borne in mind. The

principal points to be aimed at are 6, 18, and, in a less degree, 22. The

reason is that the scores 24, 12 and 8, which will just take the dealer out

from the respective points, can each be made in a variety of ways, and are

the most common for the dealer to make. The 2 points that take the score

from 4 to 6 are worth 4, or perhaps 5, average points; and the 2 points

that take the score from 6 to 8 are worth 1 point. When approaching game it

is an advantage to make a declaration that may just take the player out,

and, in a smaller degree, one that will not exactly take the adversaries

out. When the score is 24 to 22 against the dealer, hearts and clubs are

half a trick better relatively to diamonds than at the score of love-all.

In the first and second games of the rubber the value of each point scored

for honours is probably about a half of a point scored for tricks--in a

close game rather less, in a one-sided game rather more. In the deciding

game of the rubber, on account of the importance of winning the game, the

value of each point scored for honours sinks to one-third of a point scored

for tricks.

_Other Forms of Bridge._--The following varieties of the game are also

played:--

_Three-handed Bridge._--The three players cut; the one that cuts the lowest

card deals, and takes dummy for one deal: each takes dummy in turn. Dummy's

cards are dealt face downwards, and the dealer declares without seeing

them. If the dealer declares trumps, both adversaries may look at their

hands; doubling and redoubling proceeds as at ordinary bridge, but dummy's

hand is not exposed till the first card has been led. If the dealer passes

the declaration to dummy, his right-hand adversary, who must not have

looked at his own hand, examines dummy's, and declares trumps, not,

however, exposing the hand. The declaration is forced: with three or four

aces _sans atout_ (no trumps) must be declared: in other cases the longest

suit: if suits are equal in length, the strongest, _i.e._ the suit

containing most pips, ace counting eleven, king, queen and knave counting

ten each. If suits are equal in both length and strength, the one in which

the trick has the higher value must be trumps. On the dummy's declaration

the third player can only double before seeing his own cards. When the

first card has been led, dummy's hand is exposed, never before the lead.

The game is 30: the player wins the rubber who is the first to win two

games. Fifty points are scored for each game won, and fifty more for the

rubber. Sometimes three games are played without reference to a rubber,

fifty points being scored for a game won. No tricks score towards game

except those which a player wins in his own deal; the value of tricks won

in other deals is scored above the line with honours, slam and chicane. At

the end of the rubber the totals are added up, and the points won or lost

are adjusted thus. Suppose A is credited with 212, B with 290, and C with

312, then A owes 78 to B and 100 to C; B owes 22 to C.

_Dummy Bridge._--The player who cuts the lowest card takes dummy. Dummy

deals the first hand of all. The player who takes dummy always looks at his

own hand first, when he deals for himself or for dummy; he can either

declare trumps or "leave it" to dummy. Dummy's declaration is compulsory,

as in three-handed bridge. When the dealer deals for dummy, the player on

the dealer's _left_ must not look at his cards till either the dealer has

declared trumps or, the declaration having been left to dummy, his own

partner has led a card. The latter can double, but his partner can only

double without seeing his hand. The dealer can only redouble on his own

hand. When the player of dummy deals for himself, the player on his _right_

hand looks at dummy's hand if the declaration is passed, the positions and

restrictions of his partner and himself being reversed. If the player of

dummy declares from his own hand, the game proceeds as in ordinary bridge,

except that dummy's hand is not looked at till permission to play has been

given. When the player on dummy's right deals, dummy's partner may look at

dummy's hand to decide if he will double, but he may not look at his own

till a card has been led by dummy. In another form of dummy bridge two

hands are exposed whenever dummy's adversaries deal, but the game is

unsuited for many players, as in every other hand the game is one of

double-dummy.

_Misery Bridge._--This is a form of bridge adapted for two players. The

non-dealer has the dummy, whilst the dealer is allowed to strengthen his

hand by discarding four or fewer cards and taking an equal number from the

fourth packet dealt; the rest of the cards in that packet are unused and

remain unseen. A novel and interesting addition to the game is that the

three of clubs (called "Cato") does not rank as a club but can be played to

any trick and win it. The dealer, in addition to his other calls, may

declare "misery" when he has to make less than two tricks.

_Draw- or Two-handed Bridge._--This is the best form of bridge for two

players. Each player has a dummy, which is placed opposite to him; but the

cards are so arranged that they cannot be seen by his opponent, a special

stand being required for the purpose. The dealer makes the declaration or

passes it to his dummy to make by the same rules as in three-handed or

dummy bridge. The objection to this is that, since the opponent does not

see the dealer's dummy, he has no chance of checking an erroneous

declaration. This could be avoided by not allowing the dealer the option of

passing.

_Auction Bridge._--This variety of the game for four players, which adds an

element characteristic of poker, appears to have been suggested about 1904,

but was really introduced at the Bath Club, London, in 1907, and then was

gradually taken up by a wider circle. The laws were settled in August 1908

by a joint committee of the Bath and Portland clubs. The scoring (except as

below), value of suits, and play are as at ordinary bridge, but the variety

consists in the method of declaration, the declaration not being confined

in auction bridge to the dealer or his partner, and the deal being a

disadvantage rather than otherwise. The dealer, having examined his hand,

_must_ declare to win at least one "odd" trick, and then each player in

turn, beginning with the one on the dealer's left, has the right to pass

the previous declaration, or double, or redouble, or overcall by making a

declaration of higher value any number of times till all are satisfied, the

actual play of the combined hands (or what in ordinary bridge would be

dealer and dummy) resting eventually with the partners making the final

declaration; the partner who made the first call (however small) in the

suit finally constituting the trump (or no-trump) plays the hands, the

other being dummy. A declaration of a greater number of tricks in a suit of

lower value, which equals a previous call in value of points (_e.g._ two in

spades as against one in clubs) is "of higher value"; but doubling and

redoubling only affect the score and not the declaration, so that a call of

two diamonds overcalls one no-trump even though this has been doubled. The

scoring in auction bridge has the additional element that when the eventual

player of the two hands wins what was ultimately declared or more, his side

score the full value below the line (as tricks), but if he fails the

opponents score 50 points above the line (as honours) for each under-trick

(_i.e._ trick short of the declaration), or 100 or 200 if doubled or

redoubled, nothing being scored by either side below the line; the loss on

a declaration of one spade is limited, however, to a maximum of 100 points.

A player whose declaration has been doubled and who fulfils his contract,

scores a bonus of 50 points above the line and a further 50 points for each

additional trick beyond his declaration; if there was a redouble and he

wins, he scores double the bonus. The penalty for a revoke (unaffected by a

double) is (1) in the case of the declarer, that his adversaries add 150

above the line; (2) in the case of one of his adversaries, that the

declarer may either add 150 points above the line or may take three tricks

from his opponents and add them to his own; in the latter case such tricks

may assist him to fulfil his contract, but shall not entitle him to any

bonus for a double or redouble. A revoking side may score nothing either

above or below the line except for honours or chicane. As regards the

essential feature of auction bridge, the competitive declaration, it is

impossible here to discuss the intricacies involved. It entails, clearly,

much reliance on a good partner, since the various rounds of bidding enable

good players to draw inferences as to where the cards lie. The game opens

the door to much larger scores than ordinary bridge, and since the end only

comes from scores made below the line, there are obvious ways of prolonging

it at the cost of scores above the line which involve much more of the

gambling element. It by no means follows that the winner of the rubber is

the winner by points, and many players prefer to go for points (_i.e._

above the line) extorted from their opponents rather than for fulfilling a

declaration made by themselves.

AUTHORITIES.--"Hellespont," _Laws and Principles of Bridge_; W. Dalton,

_Saturday Bridge_, containing full bibliography (London, 1906); J. B.

Elwell, _Advanced Bridge_; R. F. Foster, _Bridge Tactics_; "Badsworth,"

_Laws and Principles of Bridge_; E. Bergholt, _Double-Dummy Bridge:

Biritch, or Russian Whist_, pamphlet in Brit. Mus.; W. Dalton, _Auction

Bridge_ (1908).

(W. H. W.*)

BRIDGEBUILDING BROTHERHOOD, a confraternity (_Fratres Pontifices_) that

arose in the south of France during the latter part of the 12th century,

and maintained hospices at the chief fords of the principal rivers, besides

building bridges and looking after ferries. The brotherhood was recognized

by Pope Clement III. in 1189.

BRIDGE-HEAD (Fr. _tête-du-pont_), in fortification, a work designed to

cover the passage of a river by means of fortifications [v.04 p.0532] on

one or both banks. As the process of moving an army over bridges is slow

and complicated, it is usually necessary to secure it from hostile

interruption, and the works constituting the bridge-head must therefore be

sufficiently far advanced to keep the enemy's artillery out of range of the

bridges. In addition, room is required for the troops to form up on the

farther bank. In former days, with short-range weapons, a bridge-head was

often little more than a screen for the bridge itself, but modern

conditions have rendered necessary far greater extension of bridge

defences.

BRIDGEND, a market town in the southern parliamentary division of

Glamorganshire, Wales, on both sides of the river Ogwr (whence its Welsh

name Penybont-ar-Ogwr). Pop. of urban district (1901) 6062. It has a

station 165 m. from London on the South Wales trunk line of the Great

Western railway, and is the junction of the Barry Company's railway to

Barry via Llantwit Major. Bridgend has a good market for agricultural

produce, and is an important centre owing to its being the natural outlet

for the mining valleys of the Llynvi, Garw and the two Ogwr rivers, which

converge about 3 m. north of the town and are connected with it by branch

lines of the Great Western railway. Though without large manufacturing

industries, the town has joinery works, a brass and iron foundry, a tannery

and brewery. There are brick-works and stone quarries, and much lime is

burnt in the neighbourhood. Just outside the town at Angelton and Parc

Gwyllt are the Glamorgan county lunatic asylums.

There was no civil parish of Bridgend previous to 1905, when one was formed

out of portions of the parishes of Newcastle and Coity. Of the castle of

Newcastle, built on the edge of a cliff above the church of that parish,

there remain a courtyard with flanking towers and a fine Norman gateway. At

Coity, about 2 m. distant, there are more extensive ruins of its castle,

originally the seat of the Turbervilles, lords of Coity, but now belonging

to the earls of Dunraven. Coity church, dating from the 14th century, is a

fine cruciform building with central embattled tower in Early Decorated

style.

BRIDGE OF ALLAN, a police burgh of Stirlingshire, Scotland. Pop. (1901)

3240. It lies on the Allan, a left-hand tributary of the Forth, 3 m. N. of

Stirling by the Caledonian railway and by tramway. Built largely on the

well-wooded slopes of Westerton and Airthrey Hill, sheltered by the Ochils

from the north and east winds, and environed by charming scenery, it has a

great reputation as a health resort and watering-place, especially in

winter and spring. There is a pump-room. The chief buildings are the

hydropathic and the Macfarlane museum of fine art and natural history. The

industries include bleaching, dyeing and paper-making. The Strathallan

Gathering, usually held in the neighbourhood, is the most popular athletic

meeting in mid-Scotland. Airthrey Castle, standing in a fine park with a

lake, adjoins the town on the south-east, and just beyond it are the old

church and burying-ground of Logie, beautifully situated at the foot of a

granite spur of the Ochil range.

BRIDGEPORT, a city, a port of entry, and one of the county-seats of

Fairfield county, Connecticut, U.S.A., co-extensive with the town of

Bridgeport, in the S.W. part of the state, on Long Island Sound, at the

mouth of the Pequonnock river; about 18 m. S.W. of New Haven. Pop. (1880)

27,643; (1890) 48,866; (1900) 70,996, of whom 22,281 were foreign-born,

including 5974 from Ireland, 3172 from Hungary, 2854 from Germany, 2755

from England, and 1436 from Italy; (1910) 102,054. Bridgeport is served by

the New York, New Haven & Hartford railway, by lines of coast steamers, and

by steamers to New York City and to Port Jefferson, directly across Long

Island Sound. The harbour, formed by the estuary of the river and Yellow

Mill Pond, an inlet, is excellent. Between the estuary and the pond is a

peninsula, East Bridgeport, in which are some of the largest manufacturing

establishments, and west of the harbour and the river is the main portion

of the city, the wholesale section extending along the bank, the retail

section farther back, and numerous factories along the line of the railway

far to the westward. There are two large parks, Beardsley, in the extreme

north part of the city, and Seaside, west of the harbour entrance and along

the Sound; in the latter are statues of Elias Howe, who built a large

sewing-machine factory here in 1863, and of P.T. Barnum, the showman, who

lived in Bridgeport after 1846 and did much for the city, especially for

East Bridgeport. In Seaside Park there is also a soldiers' and sailors'

monument, and in the vicinity are many fine residences. The principal

buildings are the St Vincent's and Bridgeport hospitals, the Protestant

orphan asylum, the Barnum Institute, occupied by the Bridgeport Scientific

and Historical Society and the Bridgeport Medical Society; and the United

States government building, which contains the post-office and the customs

house.

In 1905 Bridgeport was the principal manufacturing centre in Connecticut,

the capital invested in manufacturing being $49,381,348, and the products

being valued at $44,586,519. The largest industries were the manufacture of

corsets--the product of Bridgeport was 19.9% of the total for the United

States in 1905, Bridgeport being the leading city in this industry--sewing

machines (one of the factories of the Singer Manufacturing Co. is here),

steam-fitting and heating apparatus, cartridges (the factory of the Union

Metallic Cartridge Co. is here), automobiles, brass goods, phonographs and

gramophones, and typewriters. There are also large foundry and machine

shops. Here, too, are the winter headquarters of "Barnum and Bailey's

circus" and of "Buffalo Bill's Wild West Show." Bridgeport is a port of

entry; its imports in 1908 were valued at $656,271. Bridgeport was

originally a part of the township of Stratford. The first settlement here

was made in 1659. It was called Pequonnock until 1695, when its name was

changed to Stratfield. During the War of Independence it was a centre of

privateering. In 1800 the borough of Bridgeport was chartered, and in 1821

the township was incorporated. The city was not chartered until 1836.

See S. Orcutt's _History of the Township of Stratford and the City of

Bridgeport_ (New Haven, 1886).

BRIDGES, ROBERT (1844- ), English poet, born on the 23rd of October 1844,

was educated at Eton and at Corpus Christi College, Oxford, and studied

medicine in London at St Bartholomew's hospital. He was afterwards

assistant physician at the Children's hospital, Great Ormond Street, and

physician at the Great Northern hospital, retiring in 1882. Two years later

he married Mary, daughter of Alfred Waterhouse, R.A. As a poet Robert

Bridges stands rather apart from the current of modern English verse, but

his work has had great influence in a select circle, by its restraint,

purity, precision, and delicacy yet strength of expression; and it embodies

a distinct theory of prosody. His chief critical works are _Milton's

Prosody_ (1893), a volume made up of two earlier essays (1887 and 1889),

and _John Keats, a Critical Essay_ (1895). He maintained that English

prosody depended on the number of "stresses" in a line, not on the number

of syllables, and that poetry should follow the rules of natural speech.

His poetry was privately printed in the first instance, and was slow in

making its way beyond a comparatively small circle of his admirers. His

best work is to be found in his _Shorter Poems_ (1890), and a complete

edition of his _Poetical Works_ (6 vols.) was published in 1898-1905. His

chief volumes are _Prometheus_ (Oxford, 1883, privately printed), a "mask

in the Greek Manner"; _Eros and Psyche_ (1885), a version of Apuleius; _The

Growth of Love_, a series of sixty-nine sonnets printed for private

circulation in 1876 and 1889; _Shorter Poems_ (1890); _Nero_ (1885), a

historical tragedy, the second part of which appeared in 1894; _Achilles in

Scyros_ (1890), a drama; _Palicio_ (1890), a romantic drama in the

Elizabethan manner; _The Return of Ulysses_ (1890), a drama in five acts;

_The Christian Captives_ (1890), a tragedy on the same subject as

Calderon's _El Principe Constante_; _The Humours of the Court_ (1893), a

comedy founded on the same dramatist's _El secreto á voces_ and on Lope de

Vega's _El Perro del hortelano_; _The Feast of Bacchus_ (1889), partly

translated from the _Heauton-Timoroumenos_ of Terence; _Hymns from the

Yattendon Hymnal_ (Oxford, 1899); and _Demeter, a Mask_ (Oxford, 1905).

[v.04 p.0533] BRIDGES. 1. _Definitions and General

Considerations._--Bridges (old forms, _brig_, _brygge_, _brudge_; Dutch,

_brug_; German, _Brücke_; a common Teutonic word) are structures carrying

roadways, waterways or railways across streams, valleys or other roads or

railways, leaving a passage way below. Long bridges of several spans are

often termed "viaducts," and bridges carrying canals are termed

"aqueducts," though this term is sometimes used for waterways which have no

bridge structure. A "culvert" is a bridge of small span giving passage to

drainage. In railway work an "overbridge" is a bridge over the railway, and

an "underbridge" is a bridge carrying the railway. In all countries there

are legal regulations fixing the minimum span and height of such bridges

and the width of roadway to be provided. Ordinarily bridges are fixed

bridges, but there are also movable bridges with machinery for opening a

clear and unobstructed passage way for navigation. Most commonly these are

"swing" or "turning" bridges. "Floating" bridges are roadways carried on

pontoons moored in a stream.

In classical and medieval times bridges were constructed of timber or

masonry, and later of brick or concrete. Then late in the 18th century

wrought iron began to be used, at first in combination with timber or cast

iron. Cast iron was about the same time used for arches, and some of the

early railway bridges were built with cast iron girders. Cast iron is now

only used for arched bridges of moderate span. Wrought iron was used on a

large scale in the suspension road bridges of the early part of the 19th

century. The great girder bridges over the Menai Strait and at Saltash near

Plymouth, erected in the middle of the 19th century, were entirely of

wrought iron, and subsequently wrought iron girder bridges were extensively

used on railways. Since the introduction of mild steel of greater tenacity

and toughness than wrought iron (_i.e._ from 1880 onwards) it has wholly

superseded the latter except for girders of less than 100 ft. span. The

latest change in the material of bridges has been the introduction of

ferro-concrete, armoured concrete, or concrete strengthened with steel bars

for arched bridges. The present article relates chiefly to metallic

bridges. It is only since metal has been used that the great spans of 500

to 1800 ft. now accomplished have been made possible.

2. In a bridge there may be distinguished the _superstructure_ and the

_substructure_. In the former the main supporting member or members may be

an arch ring or arched ribs, suspension chains or ropes, or a pair of

girders, beams or trusses. The bridge flooring rests on the supporting

members, and is of very various types according to the purpose of the

bridge. There is also in large bridges wind-bracing to stiffen the

structure against horizontal forces. The _substructure_ consists of (a) the

piers and end piers or abutments, the former sustaining a vertical load,

and the latter having to resist, in addition, the oblique thrust of an

arch, the pull of a suspension chain, or the thrust of an embankment; and

(b) the foundations below the ground level, which are often difficult and

costly parts of the structure, because the position of a bridge may be

fixed by considerations which preclude the selection of a site naturally

adapted for carrying a heavy structure.

3. _Types of Bridges_.--Bridges may be classed as _arched bridges_, in

which the principal members are in compression; _suspension bridges_, in

which the principal members are in tension; and _girder bridges_, in which

half the components of the principal members are in compression and half in

tension. But there are cases of bridges of mixed type. The choice of the

type to be adopted depends on many and complex considerations:--(1) The

cost, having regard to the materials available. For moderate spans brick,

masonry or concrete can be used without excessive cost, but for longer

spans steel is more economical, and for very long spans its use is

imperative. (2) The importance of securing permanence and small cost of

maintenance and repairs has to be considered. Masonry and concrete are more

durable than metal, and metal than timber. (3) Aesthetic considerations

sometimes have great weight, especially in towns. Masonry bridges are

preferable in appearance to any others, and metal arch bridges are less

objectionable than most forms of girder.

Most commonly the engineer has to attach great importance to the question

of cost, and to design his structure to secure the greatest economy

consistent with the provision of adequate strength. So long as bridge

building was an empirical art, great waste of material was unavoidable. The

development of the theory of structures has been largely directed to

determining the arrangements of material which are most economical,

especially in the superstructure. In the case of bridges of large span the

cost and difficulty of erection are serious, and in such cases facility of

erection becomes a governing consideration in the choice of the type to be

adopted. In many cases the span is fixed by local conditions, such as the

convenient sites for piers, or the requirements of waterway or navigation.

But here also the question of economy must be taken into the reckoning. The

cost of the superstructure increases very much as the span increases, but

the greater the cost of the substructure, the larger the span which is

economical. Broadly, the least costly arrangement is that in which the cost

of the superstructure of a span is equal to that of a pier and foundation.

For masonry, brick or concrete the arch subjected throughout to compression

is the most natural form. The arch ring can be treated as a blockwork

structure composed of rigid voussoirs. The stability of such structures

depends on the position of the line of pressure in relation to the extrados

and intrados of the arch ring. Generally the line of pressure lies within

the middle half of the depth of the arch ring. In finding the line of

pressure some principle such as the principle of least action must be used

in determining the reactions at the crown and springings, and some

assumptions must be made of not certain validity. Hence to give a margin of

safety to cover contingencies not calculable, an excess of material must be

provided. By the introduction of hinges the position of the line of

resistance can be fixed and the stress in the arch ring determined with

less uncertainty. In some recent masonry arched bridges of spans up to 150

ft. built with hinges considerable economy has been obtained.

For an elastic arch of metal there is a more complete theory, but it is

difficult of application, and there remains some uncertainty unless (as is

now commonly done) hinges are introduced at the crown and springings.

In suspension bridges the principal members are in tension, and the

introduction of iron link chains about the end of the 18th century, and

later of wire ropes of still greater tenacity, permitted the construction

of road bridges of this type with spans at that time impossible with any

other system of construction. The suspension bridge dispenses with the

compression member required in girders and with a good deal of the

stiffening required in metal arches. On the other hand, suspension bridges

require lofty towers and massive anchorages. The defect of the suspension

bridge is its flexibility. It can be stiffened by girders and bracing and

is then of mixed type, when it loses much of its advantage in economy.

Nevertheless, the stiffened suspension bridge will probably be the type

adopted in future for very great spans. A bridge on this system has been

projected at New York of 3200 ft. span.

The immense extension of railways since 1830 has involved the construction

of an enormous number of bridges, and most of these are girder bridges, in

which about half the superstructure is in tension and half in compression.

The use of wrought iron and later of mild steel has made the construction

of such bridges very convenient and economical. So far as superstructure is

concerned, more material must be used than for an arch or chain, for the

girder is in a sense a combination of arch and chain. On the other hand, a

girder imposes only a vertical load on its piers and abutments, and not a

horizontal thrust, as in the case of an arch or suspension chain. It is

also easier to erect.

A fundamental difference in girder bridges arises from the mode of support.

In the simplest case the main girders are supported at the ends only, and

if there are several spans they are _discontinuous_ or _independent_. But a

main girder may be supported at two or more points so as to be _continuous_

over two [v.04 p.0534] or more spans. The continuity permits economy of

weight. In a three-span bridge the theoretical advantage of continuity is

about 49% for a dead load and 16% for a live load. The objection to

continuity is that very small alterations of level of the supports due to

settlement of the piers may very greatly alter the distribution of stress,

and render the bridge unsafe. Hence many multiple-span bridges such as the

Hawkesbury, Benares and Chittravatti bridges have been built with

independent spans.

Lastly, some bridges are composed of cantilevers and suspended girders. The

main girder is then virtually a continuous girder hinged at the points of

contrary flexure, so that no ambiguity can arise as to the stresses.

[Illustration: FIG. 1.--Trajan's Bridge.]

Whatever type of bridge is adopted, the engineer has to ascertain the loads

to be carried, and to proportion the parts so that the stresses due to the

loads do not exceed limits found by experience to be safe. In many

countries the limits of working stress in public and railway bridges are

prescribed by law. The development of theory has advanced _pari passu_ with

the demand for bridges of greater strength and span and of more complex

design, and there is now little uncertainty in calculating the stresses in

any of the types of structure now adopted. In the modern metal bridge every

member has a definite function and is subjected to a calculated straining

action. Theory has been the guide in the development of bridge design, and

its trustworthiness is completely recognized. The margin of uncertainty

which must be met by empirical allowances on the side of safety has been

steadily diminished.

The larger the bridge, the more important is economy of material, not only

because the total expenditure is more serious, but because as the span

increases the dead weight of the structure becomes a greater fraction of

the whole load to be supported. In fact, as the span increases a point is

reached at which the dead weight of the superstructure becomes so large

that a limit is imposed to any further increase of span.

[Illustration: FIG. 2.--Bridge of Alcantara.]