DICTIONARY OF AVIATION 239
vapor-plane 'vee-p3z,pi,een w. the plane or level at which vapor forms; the level of condensation; the plane of the altitudes or elevations at tuhich ascending currents of meist air are coold to the dewspeint and begin to con- dense into visible vapor.
vapor-pressure 'vee-p9z,p5e$9z n. the elastic pressure ex- erted by any invisible or gaseous vapor, especially that of the watersvapor in the air or atmosfere; vapor^tension.
vaporspout 'vee-pa^spaot n. same -meaning as waterspout.
vapor-tension 'vee-p3z,ten$3n n. same meaning as vapor* pressure.
vapor- value 'vee-paz/vaeliu n. the value of the water^vapor in the atmosfere; the vapor^condition, considerd quantita- tivly, of the aqueous vapor in the air, as at different ele- vations.
vapory 'vee-pa-zi adj. [also spelt vapoury] composed ef or characterized by, vapor; vaporous.
varnish. 'va:z-m$ n. a solution of resinous or elastic mate- rial in alcohol or other limpid liquid, capable of harden- ing into an elastic waterproof and gasproof coating, ap- plied to balloon^envelops to render them impermeable and wetherzproof.
veer vi:z intr. turn; shift or change direction; change; also, in meteorology, shift in the same direction as the course of the sun : as, in the northern hemisfere, from east by way of south to west : said of the wind.
vehicle-speed 'vii-i-ka^spiid n. the speed or velocity of the tjanslatory motion of a vehicle; the rapidity with which a craft moves thru the air. compare pr op ellerf speed.
velocity vi'lesi-ti n. rapidity of motion; speed or quickness in movement; siuiftness.
natural velocity, the velocity at which an aeroplane or plane aerofoil naturally continues to glide indefinitly. compare natural gliding-tangle, under glidingtangle.
velocity-potential vi'}esiti-p9,ten$3l n. a potential, or scalar quantity, whose slope is everywhere equal to the ve- locity of a mass of fluid in irrotational motion.
venation vi'nee-$3n n. the mode of distribution of the veins or nervures of an insect's wings; also, these veins collect- ivly, considerd as to their arrangement.
Venetian-blind vi'nii-$9n,blamd adj. resembling a certain type of window^blind made of slats of wood: said of a mode of aeroplane^constsuction : as, the Phillips *Venetian*: blind method.
vent-feather 'vent,fed3z n. [also spelt venttf ether] a fether located under the tail, behind the vent or anus of a bird;