Part 784

He`li*og"ra*phy (?), n. [Helio- + -graphy.] Photography. R. Hunt.

He`li*o*grav"ure (?), n. [F. hÈliogravure.] The process of photographic engraving.

He`li*ol"a*ter (?), n. [Helio- + Gr. &?; servant, worshiper.] A worshiper of the sun.

He`li*ol"a*try (?), n. [Helio- + Gr. &?; service, worship.] Sun worship. See Sabianism.

He"li*o*lite (?), n. [Helio- + -lite.] (Paleon.) A fossil coral of the genus Heliolites, having twelve-rayed cells. It is found in the Silurian rocks.

He`li*om"e*ter (?), n. [Helio- + -meter: cf. F. hÈliomËtre.] (Astron.) An instrument devised originally for measuring the diameter of the sun; now employed for delicate measurements of the distance and relative direction of two stars too far apart to be easily measured in the field of view of an ordinary telescope.

{ He`li*o*met"ric (?), He`li*o*met"ric*al (?), } a. Of or pertaining to the heliometer, or to heliometry.

He`li*om"e*try (?), n. The apart or practice of measuring the diameters of heavenly bodies, their relative distances, etc. See Heliometer.

||He`li*op"o*ra (?), n. [NL., fr. Gr. &?; the sun + &?; a passage, ||pore.] (Zoˆl.) An East Indian stony coral now known to belong to the ||Alcyonaria; -- called also blue coral.

He"li*o*scope (?), n. [Helio- + -scope: cf. F. hÈlioscope.] (Astron.) A telescope or instrument for viewing the sun without injury to the eyes, as through colored glasses, or with mirrors which reflect but a small portion of light. -- He`li*o*scop`ic (#), a.

He"li*o*stat (?), n. [Helio- + Gr. &?; placed, standing, fr. &?; to place, stand: cf. F. hÈliostate.] An instrument consisting of a mirror moved by clockwork, by which a sunbeam is made apparently stationary, by being steadily directed to one spot during the whole of its diurnal period; also, a geodetic heliotrope.

He"li*o*trope (?), n. [F. hÈliotrope, L. heliotropium, Gr. &?;; &?; the sun + &?; to turn, &?; turn. See Heliacal, Trope.] 1. (Anc. Astron.) An instrument or machine for showing when the sun arrived at the tropics and equinoctial line.

2. (Bot.) A plant of the genus Heliotropium; -- called also turnsole and girasole. H. Peruvianum is the commonly cultivated species with fragrant flowers.

3. (Geodesy & Signal Service) An instrument for making signals to an observer at a distance, by means of the sun's rays thrown from a mirror.

4. (Min.) See Bloodstone (a).

Heliotrope purple, a grayish purple color.

He"li*o*tro`per (?), n. The person at a geodetic station who has charge of the heliotrope.

He`li*o*trop"ic (?), a. (Bot.) Manifesting heliotropism; turning toward the sun.

He`li*ot"ro*pism (?), n. [Helio- + Gr. &?; to turn.] (Bot.) The phenomenon of turning toward the light, seen in many leaves and flowers.

He"li*o*type (?), n. [Helio- + -type.] A picture obtained by the process of heliotypy.

He`li*o*typ"ic (?), a. Relating to, or obtained by, heliotypy.

He"li*o*ty`py (?), n. A method of transferring pictures from photographic negatives to hardened gelatin plates from which impressions are produced on paper as by lithography.

||He`li*o*zo"a (?), n. pl. [NL., fr. Gr. &?; the sun + &?; an animal.] ||(Zoˆl.) An order of fresh-water rhizopods having a more or less ||globular form, with slender radiating pseudopodia; the sun ||animalcule.

Hel`i*spher"ic (?), Hel`i*spher"ic*al (&?;), a. [Helix + spheric, spherical.] Spiral.

Helispherical line (Math.). the rhomb line in navigation. [R.]

He"li*um (?), n. [NL., fr. Gr. &?; the sun.] (Chem.) A gaseous element found in the atmospheres of the sun and earth and in some rare minerals.

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He"lix (?), n.; pl. L. Helices (#), E. Helixes (#). [L. helix, Gr. &?;, &?;, fr. &?; to turn round; cf. L. volvere, and E. volute, voluble.] 1. (Geom.) A nonplane curve whose tangents are all equally inclined to a given plane. The common helix is the curve formed by the thread of the ordinary screw. It is distinguished from the spiral, all the convolutions of which are in the plane.