EMB 



EMB 



a corky excrescence on the bark. 

 Many of this genus are highly orna- 

 mental, as the white, campcstris, inon- 

 tana, macrophylla, gracilis, effusa, and 

 Chincnsis. 



ELUTIIIATION. The separation 

 of substances by washing them in 

 large quantities of water, so that the 

 heavier particles fall to the bottom, 

 and the lighter ones, remaining some 

 time suspended, are gradually depos- 

 ited in a finely-divided state. 



E L Y M U S. The genus of lymc 

 grasses. They are perennial, large 

 and coarse, mostly water or seashore 

 plants. The E. arcnarius is of ser- 

 vice in binding together loose sea- 

 shore sands, and resisting the en- 

 croachments of the sea. The salt- 

 marsh grasses are frequently of this 

 genus. 



ELYTRUM (from e?.vTpov, a 

 sheath). The outer hard wings of 

 beetles. 



EMACIATION. The act of be- 

 coming lean. It is a symptom of 

 diseased intestines or stomach, and 

 should be attended to at once when 

 set in ; but a sudden change of food 

 from that which is oily to starchy is 

 attended with considerable falling off. 



EMARGIXATE. In botany, notch- 

 ed, having a sharp indentation on the 

 leaf, &c. 



EMASCULATE. To castrate. 



EMBANKMENT. " It is often 

 necessary to raise mounds or dikes 

 along the course of rivers, to keep 

 them within their channels, and pre- 

 vent their flooding the lands which 



lie near them, when the waters rise 

 above their usual level. Those allu- 

 vial lands which lie near the mouths 

 of rivers, and are below the line of 

 high water, cannot be cultivated to 

 advantage unless they are secured 

 from inundation by proper embank- 

 ments ; and as these alluvial depos- 

 ites are generally very fertile, it am- 

 ply repays the expense of construct- 

 ing dikes and keeping them in repair 

 The whole of the provinces of Hoi 

 land and Zealand, and several other 

 districts in the Low Countries, could 

 not be inhabited if the sea were not 

 kept out by strong embankments; 

 and tlie destruction of a dike fre- 

 quently desolates great tracts of coun- 

 try. The art of constructing dikes, 

 and of keeping them in repair, is 

 therefore one of the greatest impor- 

 tance to the proprietors of low lands 

 situated as above described. 



"The first thing to be attended to in 

 forming embankments is to enable 

 them to resist the pressure of the 

 highest floods which are likely to oc- 

 cur, and to prevent the effect of the 

 waves and currents in washing them 

 away. When it is the simple press- 

 ure of a column of water which is to 

 be withstood, a simple earthen bank 

 made of the soil immediately at hand, 

 provided it be not of a porous nature, 

 is sufficient. Its form should be a 

 very broad base, with sloping sides 

 and with a flat top, which may serve 

 as a path, or even a carriage-road, if 

 the bank be of considerable dimen- 

 sions. The side towards the water 



should slope more gradually than to- 

 wards the land, where it may form 

 an angle of 45^^ with the horizon. A 

 ditch is usually dug along the inside 

 of the bank, and sometimes on both 

 sides, when the dike is at some dis- 

 tance from the usual channel of the 

 water, and is only a precaution against 

 unusual floods. Tht; inner ditch col- 

 lects the water which is produced by 



Y 'Z 



rains or may find its way by filtration 

 through the bank or the soil. 



" To raise these simple dikes, no- 

 thing is requisite but to carry the 

 earth from below, and consolidate it 

 by treading or ramming it in a moist 

 state, that no interstices be left. But 

 where a considerable river winds 

 through an extensive plain, and is 

 apt to change its bed by the wearing 



257 



