ARB 



03 



ARC 



ARAIOX'E'E, Fr. a spider. In military 

 affairs, a branch, return, or gallery of a 

 mine. 



ARA/LIA, a genus of American plants, 

 chiefly arborescent, of which the ange- 

 lica-tree is a species. Pentandria -Penta- 

 gynia. The berries of the angelica-tree 

 (A. spinosa) , are said to be useful in tooth- 

 ache and colic, -whence called tooth-ache 

 tree. It is also called prickly -ash. 



AR\LIA'CE.I, a natural family of plants, 

 of which the genus aralia is the type. 



ARA'NEA, a spider; a genus of arach- 

 nides, of the order pulmonariae. The spe- 

 cies are exceedingly numerous, some so 

 small as to be nearly microscopic, and 

 others so large as to kill small birds, and 

 so poisoning that their bites have proved 

 fatal to man. The domestic spider is a 

 species of this genus ; it is harmless from 

 its want of power to pierce the skin. 



A'BAR, the tree whose wood is chiefly 

 nsed by the Mahometans for the con- 

 struction of their mosques, and whose 

 resin is the sandarach of commerce. 



ARAUCA/RIA., a genus of trees somewhat 

 resembling the pine tribe. IHaecia Mo- 

 nodelphia. Named from Arancania in 

 South America, where one of the species 

 (Sir Joseph Banks' pine) grows plenti- 

 fully, and being the first discovered gave 

 name to the genus. 



AR'BALEST, \ a cross-bow, from arciu, a 

 AR'BALIST, J bow, and balista (q. v.). 

 This instrument consisted of a steel bow 

 set in a shaft or stock of wood, furnished 

 with a spring and trigger. The arrows 

 shot from it were called quarrels. 



ARBITRATION, the hearing and de 

 termining between parties in contro- 

 versy, by arbiters either chosen by the 

 parties or appointed by a magistrate. It 

 is usual for each party to choose an arbiter, 

 and these to nominate a third party called 

 an umpire. The final determination is 

 called an award; and this is binding upon 

 the parties. 



ARBITRATOR. Properly, a person to 

 whom the presiding judge proposes ques- 

 tions depending on scientific or technical 

 knowledge, which affects the matter in 

 dispute. 



AR'BOR, the Latin word for tree, as dis- 

 tinguished from shrub. 1. In gardenin 

 a bower, usually formed of lattice-work 



covered with parasitical plants, as ivy. 



2. Inmechanics, the same with shaft (q. v.). 



3. In chemistry : If mercury be thrown 



into a dilute solution of nitrate of silver 

 the silver is gradually precipitated in a 

 beautiful arborescent form, constituting 

 what is usually called the Arbor Diana 

 /the tree of D! ana') , or Arbor philosophorium 



[the philosophical tree). 4. In anatomy 



"When thi cerebellum is cut vertically 

 the medullary substance appears ramifie< 

 10 as to represent a tree : this dendriform 



arrangement is called the Arbor riiir trre 

 3f life). 5. In botany: A beautiful over- 

 green tree the Thuja occidentals! islike- 

 wise called the Arbor titee. It is a native 

 f Siberia, Canada, Japan, and China. 

 ARBo'REOrs, Lat. arborens, tree-like. 

 Having a permanent woody stem. This 

 erm is sometimes used to distinguish 

 such fungi or mosses as grow upon tree* 

 from those which grow upon the ground. 

 ARBORES'CENCE, from arboresco, to grow 

 ike a tree. The resemblance of a tree 

 frequently observed in crystallizations 

 and in mineral productions. 



ARBORES'CENT, Lat. arborescenn, groTT- 

 ng like a tree (arbor). Becoming woody ; 

 dendriform. A species of Asterias, eaUrt 

 sometimes Capttt 3Iedus<e (Medusa's head), 

 s popularly called the arborescent star- 

 fish, in allusion to its appearance. 



ARBOR'ETCM, a place in parks, pleasure 

 grounds, gardens, or nurseries, in which 

 a collection of different species of trees is 

 cultivated. 



R'BORicrtTTTRE, Lat. from arbor, a 

 tree, and colere, to cultivate. The art of 

 cultivating trees and shrubs grown for 

 timber, or for ornamental purposes. The 

 practice includes propagation by seeds, 

 by cuttings, layers, grafting, raising in 

 beds and rows, transplanting, pruning, 

 thinning, and, finally, felling, and the 

 succession of kinds. 



AR'BCTUS, the strawberry-tree. A genus. 

 Decandria Monogynia. The A. unedo, 

 or true strawberry-tree, is a beautiful 

 evergreen, which, from its frequency and 

 elegant foliage, adds greatly to the lake 

 scenery in Killarney in Ireland. The A. 

 alpina, called popularly the bear-berry, 

 bear's whortleberry, bear's bilberry, wild 

 cranberry, &e., is a trailing shrub found 

 plentifully among the Highland hills of 

 Scotland ; as is also the A. uia ursi, or red 

 bear-berry, which affords excellent food 

 for moor-fowl. This derives the name 

 from Celtic ar, rough or austere, and 

 boise, a bush, which is characteristic of 

 the Scottish species. 



ARC, Lat. arcus, a bow, vault, or arch. 

 In geometry, any part of a curved line 

 which does not consist of contrary curva- 

 tures. It is by means of circular arcs 

 that all angles are measured, the arc 

 being described from the angular point 

 as a centre. See ANGLE. 



ARCA'DE, Fr. from 8p. arcada, from Lat. 

 area. In architecture, a series of recesses 

 with arched ceilings or soffets. 



The use of this word is very vague 

 Some use it for a single arched aperture 

 or inclosure, instead of tattlt, or for the 

 space covered by a continued fault or 

 arch, supported on piers or columns, 

 instead of gallery or corridor; and by 

 others for the space inclosed by two or 

 more arcades, or a wall and an arcade, 



