DICTIONARY OF AVIATION 193
the edges of the sun, moon, and planets, often including changes of color when the stars are near the horizon or when the observer shakes his bed, and due to the irregular refraction by the warm and cold currents of the atmosfere.
scintillometer ,sinti'lemi-t3z._ n. an instrument devised by Mentigny for mesuring the scintillation of the stars.
scirocco si'zeko n. same meaning as sirocco.
scout skaut intr. observ or explore as a scout; watch the enemy's movements.
scout-airship 'skaut,e:z-$ip n. an airship which is used for scoutmg-purposes ; an aerial scouting-craft.
scouting-craft 'skau-tir),k5a:ft n. an aircraft used for scout- ing; a .scouting-airship.
scouting-machine 'skao-tin-m3,$iin n. a flying-machine designed for military scouting or reconneitering; an aerial scouting-craf t; a scouting-airship.
screw sksou n. a cylinder of wood, metal, or other material, having a spiral ridge or thred winding round it, used for fastening things together or for imparting motion; also, a rotary, bladed propeller or flyer constructed on the same principle.
aerial screw, a screw propeller designed for use in the air; an air-screw.
doubletbladed screw, a propelling-screw with two blades or vanes; a double-vaned screw.
doublefuaned screw, same meaning as doubletbladed screw.
flying screw, see flyingfscrew. screw propeller, see under propeller.
tractor screw, a screw propeller which is placed in the front or fore part of an air-craft, thus acting as a tractor drawing the machine forward; a tractor propeller; a front propeller.
screw-blade 'sksou,bleed n. one of the blades or vanes of an aerial screw, screw propeller, or lifting-screw.
screw-plane 'sksou,pLeen n. an aeroplane or aerofeil in the form of a screw; an air-screw; an aerial screw pro- peller.
screw-propeller 'sksou-psD,pel9z n. same meaning as screw propeller, see under propeller.
screw-slip 'sksuu,SLip n. the slip of a screw propeller; the drag of an air-screw.
screw- vane 'sksou,veen n. the vane of an aerial screw; a screw-blade.
scud skAd n. irregular fragments or patches of cloud torn from, or floating below, a nimbus or rain-cloud; small de-
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