Page:Dictionary of aviation.djvu/214

 190 DICTIONARY OF AVIATION

��rudder-lever 'zActo^hi-vaz n. a lever in an airship, used to

control a rudder. rudder-plane 'zAdgz^pteen n. an aeroplane used in or as a

rudder, as in a Zeppelin airship; a steenng^plane. rudder-rope 'zAda^zoop n. the rope by tuhich the steersman

or aeronaut controls the rudder of an airship. rudder- tail 'zAdaz^teel n. a tail acting as a rudder; an air-

ship^tail designed to function as a rudder; a steenng^tail. rudder-wheel 'eAdaz,iuiil n. a wheel by which the rudder of

an airship is contjold; a steermg^iuheel. rule zuul n. the expression of a uniformity among fenemena;

a minor law; a formula.

Archibald's rule, the rule stated by E. D. Archibald as to

the rate of diminution of wind^velecity with altitude. Broun' s rule, the rule stated by J. Allan Broun, in 1845,

as to the direction of the movement of lower cumulus scud,

etc.

Buchan's rule, the rule formulated by A. Buchan, in 1865,

as fellows : "Stand with your left hand toward the center of

low barometer and your right hand toward the high, then,

in the northern hemisfere, the wind will be en your

back."

Espy's rule, the rough rule stated by Espy, about 1834,

that the altitude (in feet), above the observer, of the base of

cumulus cloud is 300 times the depression of the dew-point

(in Fahrenheit degrees) at the locality of the observer. Gallon's anticyclonic rule, see under anticyclonic. Meldrum's rules, the rules formulated by C. Meldrum for

guidance in hurricanes in the Indian Ocean. These rules

were elaborated by Blanford, in 1888.

Stevenson's rule, a rule or formula stated by Stevenson

as to the velocity of wind, over level land^surfaces in-

creasing with the altitude. run zAn n. the buttock and tail (taken together) of an aero-

foil or other streamline body; the stern or afterbody of an

airship of streamline form : as, the flow has net time to

close in round the *run : distinguisht from entrance. runner 'zAnaz n. a skid, skate, or the like, attacht under a

flying^machine so as to allow it to run or slide along upon

the ground in alighting; a landing^skid. running-gear 'zAnin,gi:z n the gear or apparatus by

which a flying^machine is run or operated; the underbedy

or chassis. running-rope 'zAnirj,zoop n. a fastening^rope, as in an air-

ship or flyer, tuhich, as it is loosend or let go and allowd

to run out, permits the craft to rise.

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