240 DICTIONARY OF AVIATION
one of the under tail^coverts ; a f ether of the crissum; a crissal fether.
vertex 'vB:z,teks n. [plural vertices, vertexes] the point in the hevens directly overhed; the zenith.
vertical 'vezti-kal adj. ef or relating to the vertex or ze- nith; perpendicular to the plane of the horizon; straight up in the air : that is, not diagonal, slanting, or oblique.
angle of the vertical, the angle between the astronomical zenith and the geocentric zenith, see under zenith. This angle reaches its maximum value in latitude 45 degrees, where it is about n minutes.
vertically 'vsztxka-h adv. in a vertical manner or direction ; straight up in the air.
vertices 'vBzti,siz n. pi. see vertex.
vessel 'vesal n. an airship; an aircraft; a ship, a craft. aerial vessel, an airship.
vexilla /vek'site n. pi. see vexillum.
vexillum /vek'sitam n. [ploral vexilla] the vane or web of a bird's fether en either side of the shaft or stem; the po- gonium; the van.
viscosity ,vis'kesi-ti n. the state or property of being vis- cous; the quality of flowing slowly; also, in fysics, internal friction; resistance to the motion of the molecules of a fluid among themselvs : the epposit of mobility.
viscous 'viskas adj. having the property of viscosity or in- ternal molecular friction; characterized by resistance to internal motion; net mobile.
volant 'voo-tent adj. passing thru the air; flying; able to fly; capable of flight; velitant.
volation ,vo'lee-$an n. flight, as of a bird; the power or fac- ulty of flight; velitation.
volational ,vo'lee-$9-nl adj. of volation or flight; velita- tional.
volator ,vo'Jee-t3z n. that which flies; specifically, a flyings fish.
volitant 'veh-tnt adj. flying; capable of flight; volant: as, a bat is a velitant mammal.
volitation ,veh'tee-$9n n. the act of flying; the power or capacity to fly; the habitual practis of flight; volation; flight.
volitational ,veJi'tee-$3-nl adj. of velitation; volational.
volplane 'vel,pz,een intr. fly in, or by means ef, an aeroplane flying^machine; plane, glide, coast: as, tuhile he was "'vol- planing down to earth.
volplane 've},pi>een n. the action of the verb volplane : as, his *velplane of a mile from the clouds to the ground.
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