F A U 



F E L 



nation of it. Faults consist of fissures 

 traversing the strata, extending often for 

 several miles, and penetrating to a depth, 

 in very few instances ascertained ; they 

 are accompanied by a subsidence of the 

 strata on one side of their line, or, which 

 amounts to the same thing, an elevation 

 of them on the other ; so that it appears, 

 that the same force which has rent the 

 rocks thus asunder, has caused one side 

 of the fractured mass to rise, or the other 

 to sink. If we suppose a thick sheet of 

 ice to be broken into fragments of irregu- 

 lar area, and these fragments again united, 

 after receiving a slight degree of irregular 

 inclination to the plane of the original 

 sheet, the re-united fragments of ice will 

 represent the appearance of the compo- 

 nent portions of the broken masses, while 

 the intervening portion of more recent ice 

 represents the clay and rubbish that fill 

 the faults. In the coal-fields, these 

 faults operate as coffer-dams, and are of 

 the greatest possible advantage. 



FA'UNA. (fauni, Lat.) As the plants 

 peculiar to a country constitute its flora, 

 so do the animals constitute its fauna ,- 

 the zoology of a country. 



FAUX. (Fr.) That portion of the cavity 

 of the first chamber of a shell which may 

 be seen by looking in at the aperture. 



FAVULA'RIA. A genus of fossil plants. 

 Stem-furrowed. Scars of leaves small, 

 square, and of a breadth with the ridges 

 of the stem. In the favularia, the trunk 

 was entirely covered with a mass of dense- 

 ly imbricated foliage, the bases of the 

 leaves are nearly square, and the rows of 

 leaves separated by intermediate grooves. 

 The genus is believed to be extinct, but is 

 found fossil in the coal-formation. 



FEA'THERY. Plumose ; applied to plants 

 furnished with lateral hairs. 



FE'CAL. See F&cal. 



FE'CES. See Faeces, 



FECU'LA. (from fax, Lat. ftcule, Fr.) 



1. The sediment or grounds of any liquid. 

 The word fecula, says Dr. Paris, origin- 

 ally meant to imply any substance which 

 was derived by spontaneous subsidence 

 from a liquid. 



2. The green matter of plants. 

 FE'CUND. (facundus, Lat. ft cond, ~Fr.fe- 



condo,It.) Prolific; fruitful. 



FECUNDA'TION. (fecondation, Fr. fecon- 

 dazione, It.) Impregnation. 



FECU'NDATE. (fecondare, It. feconder, 

 Fr.) To impregnate ; to render fruitful. 



FECU'NDITY. (facunditas, 'La.t.ftconditt, 

 Fr. feconodita, It.) Fruitfulness ; pro- 

 ductiveness ; fertility ; capability of pro- 

 ducing. 



FEE'LERS. In conchology, those crenated 

 arms, evolved from the side of the Lepas 

 anatifera, and other shells of the second 



division of Lepas. While the animal is in 

 the water it continually moves its feelers, 

 evidently for the purpose of entangling 

 minute marine insects as food. Brown. 

 FE'LDSPAR. ) A mineral which enters into 

 FE'LSPAR. 5 the composition of, and, 

 next to quartz, constitutes the chief ma- 

 terial of, many rocks. There are many 

 species and subspecies, or varieties, of 

 this mineral, though all agree nearly in 

 their chemical composition, and all are 

 found both crystallized and massive. 

 Feldspar is lamellar in its structure, but 

 not in so great a degree as mica ; it 

 scratches glass, and is nearly opaque. It is 

 composed of silex 64, alumina 18, potash 

 13, lime 3, and some oxide of iron. 

 Common feldspar is perhaps the most 

 generally diffused mineral next to quartz 

 and iron. It is one of the components 

 of granite, gneiss, and some other pri- 

 mary rocks, and granite owes its variety 

 of appearance and colour principally to 

 the abundance, or otherwise, of the feld- 

 spar it contains. In some kinds of gra- 

 nite the feldspar is in large whitish crys- 

 tals of irregular forms, occasionally of 

 one or two inches in length. From the 

 liability of feldspar to be decomposed by 

 atmospheric action, granite containing 

 large crystals of it is less durable than 

 that which is finer grained, and it is said 

 that Waterloo-bridge, being unfortu- 

 nately built of granite containing large 

 crystals of feldspar, will be less durable 

 than could be wished for. Professor 

 Jameson divides feldspar into five species, 

 namely, 1. Rhombohedral Feldspar, or 

 Nepheline. 2. Prismatic Feldspar, or 

 Common Feldspar. 3. Tetarto-prismatic 

 Feldspar, or Scapolite. 4. Polychromatic 

 or Labrador Feldspar. 5. Pyramidal Feld- 

 spar, or Scapolite. 



1. Therhombohedral feldspar, or nephe- 

 line of Haiiy and Werner, is of a white or 

 grey colour, and occurs both massive and 

 crystallized; it is externally splendent, 

 internally vitreous and shining. Cleav- 

 age fourfold. Fracture conchoidal, melts 

 with difficulty before the blow-pipe. Its 

 crystals form druses. It occurs in drusy 

 cavities. Its constituent parts are, ac- 

 cording to Gmelin, silica 43-36, alumina 

 33-49, soda 13'36, potass 7'13. Other 

 authors, however, give a different analy- 

 sis, stating lime and oxide of iron to form 

 a portion of its constituents. 



2. Prismatic feldspar, or common feld- 

 spar. The prismatischer feldspath of 

 Mohs. Potash feldspar. Of this there 

 are many varieties, namely, adularia, or 

 moonstone, a transparent variety with a 

 silvery or pearly opalescence ; glassy 

 feldspar, a grey variety ; common feld- 

 spar, a translucent variety, with various 



