See also:

• WEIR (from O. Eng. wer, a dam; cognate with werian, to defend, guard; cf. Ger. Wehr, defence)
• WEIR, ROBERT WALTER (1803-1889)

WEIR (from O. Eng. wer, a See also:

• DAM

dam; cognate with werian, to defend, guard; cf. Ger. Wehr, See also:

• DEFENCE
• DEFENCE (Lat. defendere, to defend)

defence)  , a barrier placed across See also:

• RIVERS
• RIVERS, ANTHONY WOODVILLE, or WYDEVILLE, 2ND EARL (c. 1442—1483)
• RIVERS, EARL
• RIVERS, RICHARD SAVAGE, 4TH EARL (c. 1660—1712)

rivers to raise the See also:

• WATER

water-level for catching See also:

• FISH (O. Eng. fist, a word common to Teutonic languages, cf. Dutch visch, Ger. Fisch, Goth. fisks, cognate with the Lat. piscis)
• FISH, HAMILTON (1808-1893)

fish, for See also:

• MILLS, JOHN (d. 1736)
• MILLS, ROGER QUARLES (1832– )

mills, for See also:

• NAVIGATION (from Lat. navis, ship, and agere, to move)

navigation or for See also:

• IRRIGATION (Lat. in, and rigare, to water or wet)

irrigation, the See also:

• DISCHARGE (adapted from the O. Fr. discharge, modern decharge, from a med. Lat. discargare, to unload, dis- and earn care, to load, cf. " charge ")

discharge of the See also:

• RIVER

river taking See also:

• PLACE (through Fr. from Lat. platea, street; Gr. IrAar6s, wide)

place over the See also:

• CREST
• CREST (Lat. crista, a plume or tuft)

crest or through openings made for the purpose . Rough weirs, formed of stakes and twigs, were erected across See also:

• ENGLISH

English rivers in Saxon times for holding up the water and catching fish, and fish-traps, with See also:

• IRON [symbol Fe, atomic weight 55.85 (0=16)]

iron-See also:

• WIRE (A.S. wir, a wire; cf. Swed. vire, to twist, M.H.G. wiere, a gold ornament, Lat. viriae, armlets, ultimately from the root wi, to twist, bind)

wire meshes and See also:

• EEL

eel baskets, are still used sometimes at weirs . Weirs are essential for raising the See also:

• HEAD (in 0. Eng. heafad; the word is common to Teutonic languages; cf. Dutch hoofd, Ger. Haupt, generally taken to be in origin connected with Lat. caput, Gr. KerbOvi7)
• HEAD, SIR EDMUND WALKER, BART
• HEAD, SIR FRANCIS BOND, BART

head of water for water-wheels at mills, and for diverting some of the flow of a river into irrigation canals; but they have received their greatest and most varied See also:

• EXTENSION (Lat. ex, out ; tendere, to stretch)

extension in the canalization of rivers for navigation . There are three distinct classes of weirs, namely, solid weirs, draw-See also:

• DOOR (corresponding to the Gr. Bbpa,. Lat. fores or valvae; the English word, with other forms common in allied languages, comes from the same Indo-European stem as the Gr. Obpa and Lat. fares)

door weirs, including regulating sluices for irrigation, and movable weirs, which retain the water above them for navigation during the See also:

• LOW, SETH (1850- )
• LOW, WILL HICOK (1853- )

low See also:

• STAGE (Fr. 6/age; from Lat. stare, to stand)

stage of the river, and can be lowered or removed so as to leave the channel quite open in See also:

• FLOOD (in O. Eng. flod, a word common to Teutonic languages, cf. Ger. Flut, Dutch vloed, from the same root as is seen in " flow," " float ")
• FLOOD, HENRY (1732-1791)

flood-See also:

• TIME (0. Eng. Lima, cf. Icel. timi, Swed. timme, hour, Dan. time; from the root also seen in " tide," properly the time of between the flow and ebb of the sea, cf. O. Eng. getidan, to happen, " even-tide," &c.; it is not directly related to Lat. tempus)
• TIME, MEASUREMENT OF
• TIME, STANDARD

time . Solid Weirs.—The simplest See also:

• FORM (Lat. forma)

form of See also:

• WEIR (from O. Eng. wer, a dam; cognate with werian, to defend, guard; cf. Ger. Wehr, defence)
• WEIR, ROBERT WALTER (1803-1889)

weir is a solid, watertight See also:

• DAM

dam of See also:

• FIRM

firm earthwork or See also:

• RUBBLE

rubble See also:

• STONE
• STONE (0. Eng. shin; the word is common to Teutonic languages, cf. Ger. Stein, Du. steen, Dan. and Swed. sten; the root is also seen in Gr. aria, pebble)
• STONE, CHARLES POMEROY (1824-1887)
• STONE, EDWARD JAMES (1831-1897)
• STONE, FRANK (1800-1859)
• STONE, GEORGE (1708—1764)
• STONE, LUCY [BLACKWELL] (1818-1893)
• STONE, MARCUS (184o— )
• STONE, NICHOLAS (1586-1647)

stone, faced with stone pitching, with cribs filled with rubble, with See also:

• FASCINE (from the Lat. fascina, fascis, a bundle of sticks)

fascine mattresses weighted with stone, or with See also:

• MASONRY

masonry, and protected from undermining by See also:

• SHEET

sheet piling or one or more rows of well See also:

• FOUNDATIONS

foundations . These weirs, if solidly constructed, possess the advantages of simplicity, strength and durability, and require no superintendence . They, however, See also:

• BLOCK
• BLOCK (from the Fr. bloc, and possibly connected with an Old Ger. Block, obstruction, cf. " baulk ")
• BLOCK, MAURICE (1816–19or)

block up the river channel to the extent of their height, and consequently raise the flood-level above them . This serious defect of solid weirs, where the riparian lands are liable to be injured by inundations, can be slightly mitigated by keeping down the crest of the weir some-what below the required level, and then raising the water-level at the low stage of the river by placing a See also:

• ROW, JOHN (c. 1525—1580)

row of planks along the See also:

• TOP (cf. Dan. top, Ger. Topf, also meaning pot)

top of the weir . See also:

• WASTE (O. Fr. wast, guast, gast, gaste; Lat. vastus, vast, desolate)

Waste weirs resemble See also:

• ORDINARY (med. Lat. ordinarius, Fr. ordinaire)

ordinary solid weirs in providing for the surplus discharge from a See also:

• RESERVOIR

reservoir of an impounded river or See also:

• MOUNTAIN (0. Fr. montaigne; popular Lat. montanea, an adjectival form from the classical mons, montis, whence Eng. " mount," a form usually used along with the name of an individual mountain, e.g. Mt Everest)
• MOUNTAIN, THE (La Montagne)

mountain stream over their crest; but in reality they form See also:

• PART

part of a masonry reservoir dam for storing up water for water-See also:

• SUPPLY (through Fr. from Lat. supplere, to fill up)

supply or irrigation, kept purposely See also:

• LOWER

lower than the See also:

• REST (O. Eng. rest, reste, bed, cognate with other Teutonic forms, e.g. Ger. Rast, Riiste, rest, and probably Gothic Rasta, league, i.e. resting or stopping place)

rest of the dam to allow the excess of water to See also:

• ESCAPE (in mid. Eng. eschape or escape, from the O. Fr. eschapper, modern echapper, and escaper, low Lat. escapium, from ex, out of, and cappa, cape, cloak; cf. for the sense development the Gr. iichueoOat, literally to put off one's clothes, hence to sli

escape down the valley (see WATER-SUPPLY) . Draw-door Weirs.—The discharge of a river at a weir can be .egulated as required and considerably increased in flood-time by introducing a See also:

• SERIES (a Latin word from serere, to join)

series of openings in the centre of a solid weir, with sl::See also:

• ICE (a word common to Teutonic languages; cf. Ger. Eis)

ice-See also:

• GATES, HORATIO (1728-1806)

gates or panels which slide in grooves at the sides of upright frames or masonry piers erected at convenient intervals apart, and which can be raised o. lowered as desired from a See also:

• FOOT

foot-See also:

• BRIDGE

bridge . This arrangement has been provided at several weirs on the See also:

• THAMES

Thames, to afford See also:

• CONTROL (Fr. contrdle, older form contre rolle, from Med. Lat. contra-rotulus, a counter roll or copy of a document used to check the original; there is no instance in English of the use of " control " in this, its literal, meaning)

control of the flood discharge, and reduce the extent of the inundations; the largest of these composite weirs on that river is at the tidal limit at See also:

• TEDDINGTON

Teddington, where the two central bays, with a See also:

• TOTAL

total length of 242ii-, ft., are closed by See also:

• THIRTY

thirty-five draw-doors sliding between iron frames supporting a foot-bridge, from which the doors are raised by a winch.' Ordinary draw-doors, sliding in grooves of moderate See also:

• SIZE

size and raised against a small head of water, can be readily worked in spite of the See also:

• FRICTION (from Lat. fricare, to rub)

friction of the sides of the doors against their supports; but with large draw-doors and a See also:

• CON

con- siderable head, the friction of the surfaces in contact offers a serious impediment in raising them . This fric- tion has been greatly re- duced by making the draw- doors, or sluice-gates, slide on each See also:

• SIDE
• SIDE (mod. Eski Adalia)

side against a verti- cal row of See also:

• FREE

free-rollers See also:

• SUS

sus- pended by an encircling See also:

• CHAIN (through the O. Fr. citable, chcene, &c., from Lat. catena)

chain; and the working a is much facilitated by FIG .

2.—Mechanism of Lifting-See also:

• GATE

gate, counterpoising the doors . See also:

• RICHMOND
• RICHMOND, EARLS AND DUKES OF
• RICHMOND, LEGH (1772-1827)
• RICHMOND, SIR WILLIAM BLAKE (1842– )

Richmond . By these arrangements the large draw-door weir across the Thames at Richmond, with three spans of 66 ft. closed by lifting doors, each 12 ft. high and weighing 32 tons, can be fully opened in seven minutes by two men raising each door from the arched See also:

• DOUBLE
• DOUBLE (from the Mid. Eng. duble, the form which gives the present pronunciation, through the Old Er. duble, from Lat. duplus, twice as much)

double foot-bridge (See also:

• FIGS

figs . 1, 2 and 3) . This weir retains the river above it at See also:

• HALF

half-See also:

• TIDE (O. Eng. lid, cf. Ger. Zeit, time or season, connected with root of Sanskrit a-diti, endless)

tide level, in See also:

• ORDER
• ORDER (through Fr. ordre, for earlier ordene, from Lat. ordo, ordinis, rank, service, arrangement; the ultimate source is generally taken to be the root seen in Lat. oriri, rise, arise, begin; cf. " origin ")
• ORDER, HOLY

order to See also:

• COVER (from the Fr. convert, from couvrir, to cover, Lat. cooperire)

cover the mud-See also:

• BANKS, GEORGE LINNAEUS (1821-1881)
• BANKS, NATHANIEL PRENTISS (1816–1894)
• BANKS, SIR JOSEPH
• BANKS, THOMAS (1735-1805)

banks which had been bared at low tide between Richmond and Teddington by the lowering of the low-water level, owing to the removal of various obstructions in the river below . The weir is raised out of the river as soon as the flood-tide on its lower side has risen to half-tide level, so as not to impede the flow and ebb of the tide up to Teddington above that level, and is not lowered till the tide has fallen again to the same level . In order that the doors when raised may not impede the view under the See also:

• ARCHES, COURT OF

arches, ' L . F . See also:

• VERNON
• VERNON, EDWARD (1684-1757)

Vernon-See also:

• HARCOURT
• HARCOURT, SIMON HARCOURT, 1ST VISCOUNT (c. 1661-1727)
• HARCOURT, SIR WILLIAM GEORGE GRANVILLE VENABLES VERNON (1827-1904)
• HARCOURT, WILLIAM VERNON (1789-1871)

Harcourt, Rivers and Canals, 2nd edition, p . 114, and See also:

• PLATE

plate iii. figs . 15 and 16.the doors are rotated automatically at the top by grooves at the sides of the piers, so as to assume a See also:

• HORIZONTAL

horizontal position and pass out of sight in the central space between the two foot-ways (fig . 2) .

The barrage at the head of the See also:

• NILE
• NILE, BATTLE OF THE
• NILE, SOBAT

Nile See also:

• DELTA (from the shape of the Gr. letter A, delta, originally used of the mouth of the Nile)

delta, and the regulating sluices across the Nile at See also:

• ASSIUT, or SLUT

Assiut and See also:

• ESNA, or ESNEH

Esna in Upper See also:

• EGYPT

Egypt below See also:

• ASSUAN

Assuan, are examples of draw-door weirs, with their numerous openings closed by sluice-gates sliding on free rollers, which control the discharge of water from the river for irrigation . Movable Weirs.—There are three See also:

• MAIN (from the Aryan root which appears in " may " and " might," and Lat. magnus, great)
• MAIN (Lat. Moenus)

main types of movable weirs, namely See also:

• FRAME

frame weirs, shutter weirs and See also:

• DRUM (early forms drome or dromme, a word common to many Teut. languages, cf. Dan. tromme, Ger. Trommel: the word is ultimately the same as " trumpet," and is probably onomatopoeic in origin; it appears late in Eng. about the middle of the 16th century)

drum weirs, which, however, See also:

• PRESENT

present several See also:

• VARIATIONS
• VARIATIONS, CALCULUS
• VARIATIONS, CALCULUS OF

variations in their arrangements . The ordinary form of frame weir consists of a series of iron frames placed across a river end on to the current, between 3 and 4 ft . apart, hinged to a masonry See also:

• APRON (a corruption arising from a wrong division of " a napron " into " an apron," from the Fr. naperon, napperon, a diminutive of nappe, Lat. mappa, a napkin)

apron on the See also:

• BED
• BED (a common Teutonic word, cf. German Bett, probably connected with the Indo-European root bhodh, seen in the Lat. fodere, to dig; so " a dug-out place " for safe resting, or in the same sense as a garden " bed ")

bed of the Frame river and carrying a foot-bridge along the top, from which weir. the actual barrier, resting against the frames and See also:

• CROSS

cross- bars at the top and a See also:

• SILL
• SILL (O.Eng. syl, Mid. E. sylle, selle; the word appears in Icel. syll, svill, Swed. syll, and Dan. syld, and in German, as Schwelle; Skeat refers to the Teutonic root swal-, swell, the word meaning the rise or swell formed by a beam at a threshold; the L
• SILL, EDWARD ROWLAND (1841-1887)

sill at the bottom, is put into place or removed for closing or opening the weir . The barrier was originally formed of a number of See also:

• LONG, GEORGE (1800-1879)
• LONG, JOHN DAVIS (1838– )

long square wooden spars which could be readily handled by one See also:

• MAN
• MAN, ISLE OF (anc. Mona)

man, being inclined slightly from the See also:

• VERTICAL (from Lat. vertex, highest point)

vertical and placed See also:

• CLOSE
• CLOSE (from Lat. clausum, shut)
• CLOSE, MAXWELL HENRY (1822-1903)

close together for shutting the weir; but panels of See also:

• WOOD, ANTHONY A2 (1632-1695)
• WOOD, JOHN GEORGE (1827—1889)
• WOOD, MRS HENRY [ELLEN] (1814—1887)
• WOOD, SEARLES VALENTINE (1798—188o)

wood or sheet-iron closing the space between adjacent frames and sliding in grooves at the sides, and See also:

• ROLLING

rolling-up curtains composed of a series of horizontal wooden laths connected by leathern hinges, have also been employed . The See also:

• NEEDLE (O. Eng. ncedl; the word appears in various forms in Teutonic languages, Ger. Nadel, Dutch naal, the root being ne-, to sew, cf. Ger. nahen, and probably Lat. nere, to spin, Gr. vi)ats, spinning)

needle weir, so called from the Iong, slender spars being termed aiguilles in See also:

• FRANCE
• FRANCE, ANATOLE (1844– )

France, had the merit of simplicity in its earliest form; and by means of some ingenious contrivances, comprising a See also:

• HOOK, JAMES CLARKE (1819-1907)
• HOOK, THEODORE EDWARD (1788-1841)
• HOOK, WALTER FARQUHAR (1798-1875)

hook, winch, See also:

• LEVER (through O. Fr. leveour, levere, mod. levier, from Lat. levare, to lift, raise)
• LEVER, CHARLES JAMES (1806-1872)

lever and rotating See also:

• BAR
• BAR (0. Fr. barre, Late Lat. barra, origin unknown)
• BAR, CONFEDERATION OF
• BAR, FRANCOIS DE (1538-1606)
• BAR, THE

bar, for assisting the weir-keepers in placing and releasing the needles, the See also:

• SYSTEM

system has been applied successfully to the weirs of greater height required on the See also:

• MEUSE
• MEUSE (Flem. Maes, Du. Maas)

Meuse, the Main and the Moldau (fig . 4) . The needle weir has, however, attained its greatest development in the See also:

• UNITED

United States across the Big Sandy river at Louisa, where, instead of needles 3 to 4 in. square, beams 12 in. square and 182 ft. long have been resorted to, provided with a See also:

• STEEL, FLORA ANNIE (1847– )

steel See also:

• EYE
• EYE (O. Eng. edge, Ger. Auge; derived from an Indo-European root also seen in Lat. oc-ulus, the organ of vision (q.v.)

eye at the top and a See also:

• RING (O.E. hring; a word common to Teutonic languages; and probably cognate with the Lat. circus, Gr. KtpKOS or KpLKOS, Skt'. chakra, wheel, circle, cf. also " harangue "); in art, a band of circular shape of varying sizes, made of any material and used f

ring near the centre of gravity to enable them to be worked (fig . 5) . The needles are put in place one by one against the raised frames, or trestles, by a See also:

• DERRICK

derrick on a See also:

• BARGE (Med. Lat. barca, possibly connected with Lat. baris, Gr. flaps, a boat used on the Nile)

barge lifting them by their ring, whilst a man on the foot-bridge, taking hold of the eye at the top, arranges them in position close together . The weir is opened by joining the needles of each See also:

• BAY

bay by a chain passed through the eyes at the top and a See also:

• LINE

line of wire through the central rings, so that when released at the top by the tilting of the escape bar by the derrick, they See also:

• FLOAT (in O. Eng. floc and flota, in the verbal form f eotan; the Teutonic root is flut-, another form of flu-, seen in " flow," cf. " fleet "; the root is seen in Gr. a-M e, to sail, Lat. pluere, to rain; the Lat, fluere and fluctus, wave, is not connect

float down as a raft, and are caught by a man in a See also:

• BOAT (0. Eng. bdt; the true etymological connexion with Dutch and Ger. boot, Fr. bateau, Ital. battello presents great difficulties; Celtic forms are from O. Eng.)

boat, or, when the cur- See also:

• RENT

rent is strong, they arer,a0oosgo See also:

• OHIO

OHIO See also:

• DRAWN

drawn to the See also:

• BANK

bank by— a rope attached to them previously to their See also:

• RELEASE (O.Fr. reles, variant of relais, from relaisser, to release, let go, Lat. relaxare)

release . The trestles of this weir are, as usual, hinged to the apron, so that in flood-time they can be completely lowered FIG .

5.—Spar Weir, Louisa, Big Sandy into a See also:

• RECESS (Lat. recessus, a going back, withdrawal, from recedere, to withdraw)

recess across the River, U.S.A . apron by means of chains actuated by a winch, leaving the channel perfectly open for the discharge of floods and for the passage of vessels when the See also:

• LOCK (from the O. Eng. loc.; the word appears, in different forms, in many Teutonic languages, but with such various meanings as " hole," Ger. Loch, " lid," Swed. lock, &c.; probably the original was a root meaning " to enclose ")
• LOCK, MATTHIAS

lock is submerged . Whereas, however, ordinary frames placed nearer together than their height overlap one another when lowered on to the apron, the trestles of the Louisa weir See also:

• LIE, JONAS LAURITZ EDEMIL (1833—1908)
• LIE, MARIUS SOPHUS (1842–1899)

lie clear of each other quite See also:

• FLAT (a modification of O. Eng. flet, an obsolete word of Teutonic origin, meaning the ground beneath the feet)

flat on the apron . The frame weir closed by sliding panels or rolling-up curtains (fig . 6) possesses the See also:

• ADVANTAGE

advantage that the panels or laths can be diminished in thickness towards the top in proportion to the reduced water-pressure; whereas the needles, being of See also:

• UNIFORM

uniform cross-See also:

• SECTION
• SECTION (Lat. sectio, cutting, secare, to cut)

section, have to be made stout enough to sustain the maximum bottom pressure . An objection has occasionally been urged against frames lowered on to the bed of a river that they are liable to be covered over by detritus or See also:

• DRIFT (from "drive ")

drift brought down by floods, and consequently are subject to injury or impediments in being raised .