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 DICTIONARY OF AVIATION 195

the lateral motions of the driver's body are communicated to the balancing-planes, compare bodyicradle and shoulder* yoke.

secondary 'sekan/lez-i n. a secondary remex or flight-fether of a bird's wing; one of the large quill-fethers of a bird's wing which are seated upon the forearm, between the pri- maries and tertiaries.

section 'sekj^n n. a cutting or division; a representation, as of an aerofoil or airship as it would appear if cut by an intersecting plane : as, a longitudinal *section, a tjans- verse *section.

fish section, a section, as of a streamline bedy, which resembles the longitudinal section of a fish, being blunt at one end and tapering at the other end.

sectional 'sek$9-nl adj. characterized by the presence of sections, divisions, or compartments : as, the *sectional con- struction of a Zeppelin airship.

self-raising ,self'zee-zirj adj. capable of raising or lifting itself into the air : as, a *self-raising, self-sustaining, and self-propelling flying-machine.

self-register ^elfzedsi-st^z n. an automatic register or srlf-registering device, as for an anemometer.

self-registering ,srlf'rrd5i-str,irj adj. registering automat- ically; sHf-rccerding : as, *self-registenng instruments; a
 * selfsiregrstering balloon.

self-righting ^elf zai-tirj adj. capable of righting itself, as a gliding-machine, when capsized or disturbed in its mo- tion or balance.

self-sustained ,se}f-S9'steend adj. [also spelt selftsustaind] sustaind or held up in the air by its own power or move- ment, altho hevier than air, as an aeroplane flying-machine.

self-sustaining ,self-s9'stee-nir| adj. capable of sustaining or holding itself up in the air, as a flying-machine.

semirigid /semi'zidsid adj. [also spelt semi-rigid'} partly rigid : said of balloons, airships, or gas-vessels which are neither wholly rigid nor wholly non-rigid.

sennit 'senit n. [also spelt sennet] flat braided cordage, some- times used as belting for transmitting power from the motor to the propeller in airships.

settle 'set! intr. descend gradually; sink.

sextant 'sekstnt n. an instrument consisting of a graduated arc of a sixth part of a circle, used for mesuring the angu- lar distance of two stars or other distant objects in the sky, er the altitude of a star above the horizon.

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