ECH 



285 



ECH 



n*s for working the -valves of steam- en- 

 gine*. It consists of a wheel situated 

 upon the main-shaft, but fixed out of its 

 centre. It is fitted in a brass ring to 



tus, bristly; set 



which shafts are attached ; these are con- 

 nected with the valve-lever, so that, as 

 the eccentric turns round with the shaft, 

 an alternate motion is communicated to 

 the lever, and the valves thereby opened 

 and closed. In astronomy, the eccentric 

 place of a planet is its place as it would 

 appear to a spectator at the sun, and 

 which, when referred to the ecliptic, co- 

 incides with, the heliocentric longitude. 

 And the distance between the centre of 

 the planet's orbit and focus is called the 

 planet's eccentricity, a term used to de- 

 note the distance of either focus of an 

 ellipse from the true centre. 



ECCHE'IA, } from yyt"' to sound - So- 



ECHE'A, ) norous bell-shaped vases of 



bronze, &c., used in the construction of 



ancient theatres, to give additional power 



to the voices of the actors. 



ECCLESIASTICAL COURTS. The Archdea- 

 con's, the Consistory, the Court of Arches, 

 the Peculiars, the Prerogatht, and the 

 Court of Delegates. 



ECCLE'SIA, izzXvirict. In ancient history, 

 the great assembly of the Athenian people, 

 at which every free citizen had a vote. 



EccRixoL'oor.from tzxyvu, to excrete, 

 and Aayef , discourse, the doctrine of ex- 

 cretions. 



ECH'ELON (Fr.), from fchelle, a ladder, a 

 scale. A term used by military tacticians, 

 to denote the position of an army, when 

 the divisions of which it is composed 

 inarch on parallel lines, but all differently 

 advanced. The object is to bring one 

 part into action, and reserve the others. 

 ECHE'NEIS, a genus of fishes ; order Ma- 

 lacopterygii sttb-brachiati, and family Dis- 

 coboli, Cuv. There are two species. The 

 best known is the Remora (tlieE.remora, 

 Lin.) which inhabits the Mediterranean. 

 It is sometimes called the Sucking-fish, 

 from its attaching itself firmly to bodies, 

 as ships at sea, sharks, and other large 

 fishes. From this it takes its generic 

 name, i%et, to detain, and ^vs , a ship, 

 as it was supposed capable of stopping a 

 ship on her course. 



ECH'IMTS, from i%i( and put, the 

 spring-rat; a genus of mammalia of the 

 rodentian order, considerably larger than 

 the brown rat. The fur of some of the 

 species is intermixed with flattened spines 

 like sword blade*. America. 



ECHINODER'MATA, echinoderms, a class 

 of radiated animals, thus named from 

 t%,ivos, a hedgehog, and gs^at, skin, as 

 the skin is generally armed with points or 

 moveable spines. The star-fish and sea- 

 urchin are examples. 



ECHINORHTNCCS, a numerous genus of 

 intestinal worms composing the family 

 Acanthocephala of Cuvier. Name from 

 vo;> a hedgehog, and ^vy^6;, a probo- 

 scis. The E. bicornis only has been found 

 n the human subject. 



ECHI'NUS, IKIVOS , the hedgehog. 1. The 

 generic name of the sea-urchins : Class 

 Echinodermata ; order Pedicellata, Cuv. The 

 body is invested by a shell or calcareous 

 crust, composed of angular pieces, which 

 join together exactly. The surface is armed 

 with spines which move at the will of the 

 animal. The animal feeds on shell-fish.- 

 The shells of echini are very abundant in 

 ancient strata, principally those of chalk, 

 where they are usually filled with silex. 



2. In architecture, an ornament near 



the bottom of the Ionic, Corinthian, and 

 Composite capitals. It is a convex mould- 

 ing, generally ornamented with sphe- 

 roids ; the upper ends cut off ; the upper 

 part of the axis projecting and the lower 

 receding. The echinus is only used in 

 columns, in the entablature and capital. 



E'CHinM.the viper-bugloss, a numerous 

 genus of plants. Pcntnndria Monogynia. 

 Name from i%it, a viper ; because it was 

 supposed to heal the sting of a viper. 



ECH'O, from Yi^ot, sound; a sound re- 

 flected from some surface, and thence 

 repeated to the ear. That a speaker may 

 hear a distinct echo of his own voice, he 

 must stand at least 63 feet from the re- 

 flecting surface. This is owing to the 

 relation between the velocity with which 

 sound travels and the readiness of the ear 

 to distinguish sounds. Caverns, grottoes, 

 mountains, and ruined buildings gene- 

 rally, reflect sound; and as every point 

 against which the pulses of sound strike 

 becomes the centre of a new series of 

 pulses, and as sound describes equal dis- 

 tances in equal times, these frequently 

 give more than a single echo of a sound. 

 That at Woodstock, in Oxfordshire, re- 

 peats the same sound 50 times. Archi- 

 tects have exercised their ingenuity in 

 i the construction of vaults, arches, &c., 



