EEL-GRASS 



Eel-grass ( Valisneria spiralis). 

 Perennial aquatic herb of the 

 natural order Hydrocharidaoeae 

 It is a native 

 of warm and 

 temperate re- 

 gions, includ- 

 ing S. Europe. 

 The short stem 

 is immersed in 

 the mud of 

 rivers and 

 lakes, and from 

 itarisesatuftof Eel-grass. Plants 

 thin grass-like of the aqaatic herb 

 leaves a yaid long, but only i in. 

 wide. The female flower has a very 

 long spiral stalk which enables it 

 to lie upon the surface of the water. 

 The male flowers (produced by 

 separate plants) have very short 

 stalks which break away from 

 their attachment, so that they float 

 to the surface, where they pollinate 

 the females. This accomplished, 

 the female, by the spiral contrac- 

 tion of its stalk, is withdrawn to 

 the bottom, where it develops into 

 a cvlindrical berry. 



Eel Pie Island. Islet in the 

 Thames opposite York House, 

 Twickenham. Also called Twicken- 

 ham Eyot, it has long been noted 

 as a favourite resort of anglers and 

 boating parties. The inn on the 

 islet occupies the place of Eel Pie 

 House, pulled down in 1830. 



Eel Pout (Lota vulgaris). Popu- 

 lar name for the burbot. It is a 

 fresh-water fish, common in Euro- 

 pean and American rivers, but found 

 in Great Britain chiefly in the Cam 

 andtheOuse. Itisaboutayardlong, 

 and somewhat eel-like in shape. 



Effendi. Turkish title of re- 

 spect. * It is applied in the East to 

 government officials, men of learn- 

 ing, and others. It is a corruption 

 of the Greek authentes (mod. pron. 

 afthendes), a lord. 



Effervescence (Lat. efferves- 

 cere, to boil up). Name applied 

 to the phenomenon of the rapid 

 escape of gas from a liquid. It 

 is usually the result of chemical 

 action. A familiar example is seen 

 in the mixing of a seidlitz powder 

 with water. When soda water is 

 withdrawn from a syphon the 

 evolution of carbon dioxide is du- 

 to physical causes. 



Efficiency (Lat. efficientia, a 

 carrying out) Term meaning in 

 general the quality of producing 

 some desired result. Apart from 

 its use in engineering, it is in- 

 creasingly used in industrialism and 

 economics, considerable attention 

 being paid by doctors and others 

 to the efficiency of the worker. 



In engineering, efficiency is the 

 ratio of the amount of energy 

 given out from a conducting, con- 

 verting, or transmitting device to 



2810 



the energy received by it. In all 

 cases the efficiency is less than 

 unity, as some of the energy is 

 dissipated or used up unprofitably. 

 The efficiency of a joint is the 

 ratio of the strength of the joint 

 to a similar section of unjointed 

 material. In aeronautics, where 

 the main spars are spliced, the 

 efficiency of the splice is its 

 strength relative to that of the 

 unspliced wood of similar section. 

 The heat-absorbing efficiency of 

 a boiler is represented by the per- 

 centage of the heat units of the 

 burnt fuel which is found in the 

 water and steam. The efficiency in 

 very good boilers may be as high 

 as 80 p.c. The heat-converting 

 efficiency of a steam engine is its 

 capacity for converting units of 

 heat energy into units of me- 

 chanical work on the basis of one 

 thermal unit being equivalent to 

 778 foot-pounds of work. So much 

 heat is wasted by conduction, con- 

 densation, etc., that the efficiency, 

 even in the best engines, does not 

 exceed 15 p.c. to 18 p.c. The brake 

 or effective h.p. of an engine is less 

 than the indicated h.p., owing to 

 loss in overcoming friction. Simi- 

 larly, the converting efficiency of 

 a dynamo or electric motor re- 

 spectively is its capacity for trans- 

 forming mechanical into electrical, 

 or electrical into mechanical energy. 

 The difference between energy 

 units received and delivered de- 

 cides the transmitting efficiency of 

 lines of shafting, belt drives, etc. 



EFFIGY 



A good example of the cumula- 

 tive effect of losses due to effi- 

 ciencies being less than unity is 

 afforded by the propelling appa- 

 ratus of a ship. Assuming a 

 boiler efficiency of 75 p.c., an 

 engine heat-efficiency of 15 p.c., a 

 transmitting efficiency of 90 p.c., 

 and a propeller efficiency of 60 p.c. 

 all well above the average out 

 of 100 units of heat-energy de- 

 veloped by the burning of boiler fuel 

 only (100X T V<y X ^ X &% X T ff ) 

 =6'075 p.c. are con verted into use- 

 ful work. See Boiler; ; Steam Engine. 



Effigy (Lat. effigies, image, like- 

 ness ). Monumental effigies on tomb- 

 lids in Christian churches from the 

 13th century onwards abound in 

 England and W. Europe. Originally 

 carvings in low relief, which gave 

 rise to monumental brasses, they 

 developed into figures in the round, 

 usually recumbent. Ancestral effi- 

 gies, kept in great houses in ancient 

 Egypt and Rome, suggested to 

 medieval Europe the funeral effigies 

 placed upon the biers of royal and 

 other personages. 



In primitive culture effigies are 

 important adjuncts of sympathetic 

 magic. There are palaeolithic 

 cave-portraits of food-animals, 

 speared symbolically to ensure 

 success in hunting. The piercing 

 or melting of waxen images to 

 induce sickness or death, practised 

 in early Egypt, Babylonia, Vedic 

 India, Greece, and Rome, prevailed 

 throughout 13th -17th century 

 Christendom. See Numismatics. 



Effigy. 

 mi DS tor 



Two examples in wax. Left: Effigy of Queen Elizabeth in West- 

 Abbey. Right (by courtesy of Messrs. Tussaitd): Effigy of Queen 

 Marie Antoinette, originally shown at Versailles 



