A R A C i£) ) ARC
APPROXIMATION, (approxima-tion, Fr.) in arithmetic or algebra, is acontinued approaching still nearer andnearer to the root or quantity sought,without ever expecting to have it exactly.
APPUI, with horsemen, the stay up-on the horsemans hand, or the recipro-cal sense between the horse’s mouthand the bridle hand; or the horse’ssense of the action of the bridle in thehorseman’s hand. Horses for the armyought to have a full appui, or firm stayupon the hand.
A full Appui, in horsemanship, afirm stay without resting very heavy,and without bearing upon the horse-man’s hand.
A more than full Appui, upon thehand, is when the horse is stopped withsome force; but still so that he doesnot force the hand. This appui is goodfor such riders as depend upon the bri-dle, instead of their thighs.
Appui, (point d'appui , Fr.) any par-ticular given point or body, upon whichtroops are formed, or by which they aremarched in line or column.
Alter d /’Appui, Fr. to go to the as-sistance of any body; to second, to back.
Hauteur //’Appui, Fr. breast-height.
APPUYER, Fr. to sustain, to sup-port. Hence, unc urm'ce appuyte dunhois, dun mar ah; an army which has awood or a marsh on either of its flanks.
Appuyer also signifies to force anything into an object; as, appuyer Vtptronsi un cheval, to drive the spurinto a horse.
APPRELLE, Fr, horse-tail.
APRON, in gunnery, a square plateof lead that covers the vent of a cannon,to keep the charge dry, and the ventclean and open.
AQUEDUCT , a channel to conveywater from one place to another. Aque-ducts, in military architecture, are ge-nerally made to bring water from aspring or river to a fortress, &c.; theyare likewise used to carry canals overlow grounds, and over brooks or smallj’ivers : they are built with arches like abridge, only not so wide, and are cover-ed above by an arch, to prevent dust ordirt from being thrown into the water.See Muller’s Practical Fortification.
The Romans had aqueducts which ex-tended 100 miles. That of Louis XIV .near Maintenon , which carries the riverBute to Versailles , is 7000 toises long.
ARAIGNEE, Fr, in fortification. SeeGallery.
ARABESQUE,^ something done af-
ARABESK, ) ter the manner ofthe Arabians .
Arabesk, grotesque, and moresque, areterms applied to such paintings, orna-ments of friezes,, &c. on which there areno human or animal figures; hut whichconsist wholly of imaginary foliages,plants, stalks, &c.
The terms are derived from the Arabs ,Moors , and other Mahometans, whouse these kinds of ornaments, becausetheir religion forbids them to make anyimages or figures of men, or of otheranimals.
ARABIAN horse, a horse supposedto be of high value, but not so useful asthe common English breed.
ABASEMENT, Fr. in masonry, thelast course of stone or brick upon a wallof an equal height.
ARASER, Fr. to carry the differentcourses of stone or brick to an equalheight.
A RASES, Fr. stones or bricks whichare larger or smaller than those of theother courses, and are used to make anygiven height.
ARBALET , in the ancient art of war,a cross-how, made of steel, set in a shaftof wood, with a string and trigger, bentwith a piece of iron fitted for that pur-pose, and used to throw bullets, largearrows, darts, &c. Also a mathemati-cal instrument called a Jacob's Staff] tomeasure the height of the stars upon thehorizon.
ARBALETE a jalet, Fr. a stone how.
ARBALETRIER, Fr. a cross-bow-man.
A RBALETitiF.it dune galicre, Fr.that part of a galley where the cross-bowmen were placed during an engage-ment.
ARBORER, Fr. to plant, to hoist.Arborer Vetendart, to plant the stand-ard.
ARBRE , Fr. tree; in mechanics, thethickest piece of timber upon which allother pieces turn, that it supports.
ARC, Fr. a bow; an arch in building.
Arc en plein ceintre , Fr. ia architec-ture, an arch which is formed of a per-fect half-circle.
Arc en anse dc panier,Tr. au ellipticarcli drawn upon three centers.
Arc buns, ou de cote, Fr. an archwhose piedroits are not even with theirplans.
Arc rampant, Fr. that which in anD. 2