Page:Dictionary of aviation.djvu/148

 124 DICTIONARY OF AVIATION

cepter type invented by Hiniker; a flyer with revolving aeroplanes.

helicopter ,heli'kept9z, ,hili'kept9z n. [synonymous cognate helicoptere, helicoptere'} a flymg-machine invented by Pe- naud about the year 1870; also, any one of various similar flying^machines, such as those designed or advocated by Leonardo da Vinci, Launoy and Bicnvenu, Phillips, Edison, Berliner, Cernu, and others, depending, for lifting? or sus- taining^power, upon vertical screws or rotating aerofoils; a f lying^screw ; a gyroplane : distinguisht from aeroplane and ornithopter.

helicopteric / heh / kopt3-^ik adj. of the nature of a heli- copter or verticakscrew flyer.

helicoptic ^eli'koptik adj. same meaning as helicopteric. helicoptically ,heli'keptik3-li adv. by means of, or in the

manner of, a helicopter : as, to fly *helicoptically. helices 'heli,siz n. pi. see helix.

heliophotometer ,hii-li-o-f3'temi-t9z n. [also spelt hello- fotometer"} an instrument for mesunng and recording the duration of sunlight introduced by F. Craveri about 1874. helix 'hii-liks n. [plural helices, helixes'} anything of a spi- ral or ceild form whether in two dimensions (like a watch^ spring) or in three dimensions (like a corkscrew) ; (in ge- ometry) a curv formd by a straight line traced on a plane surface which is then wrapt round a cylinder; a curv on any developable surface which becomes a straight line when the surface is unrolled into a plane ; a gyre : some- times distinguisht from spiral, which is often a plane curv. helix of travel, the helix or helical curv described by the extremity of the blade of a screw propeller in its travel or translatory motion thru the air. helm helm n.

1. the handle, tiller, or uuheel by which the rudder of an airship is managed; the steering-wheel ; the steering-gear.

2. a helm-cloud; a helmet.

helm-bar 'helm,ba:z n. a bar of cloud fermd at the summit of a standing wave of air; a roll of cloud suspended below a helm-cloud.

helm-cloud 'helm,k;Laud n. a stationary cloud formd at the summit of a standing wave of air; a dark cloud which rests en the brow of a mountain before a storm; a helm or helmet.

helmet 'helmit n. a helm-cloud; a helm.

helm-wind 'helm,wind n. a wind which produces helm or helm-cloud.

hemipter hi'miptsz n. any insect of the erder hemiptera.

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