helen1um

[Lat. Helenium; Gr. helen i on =a plant, perhaps elecampane. ( Liddell & Scott.)] Bot.: The typical genus of the sub-tribe Heleniese (q. v.). The species are yellow-flowered plants of this country. hê-li-, hê-li-o-, pref. [Greek helios =the sun.] [HELIACAL.] hê-li-ạc, hế-li-ac-al, a . [Gr. hēliakos =of or belonging to the sun, helios =the sun; cf. Sansc. sura =the sun; Lat. sol ; Goth. sunna ; Eng. sun (q. v.).] Astron.: Closely connected with the sun; rising just before the sun; a term used when a star rises just before the sun. As the sun moves in its orbit, a particular star which had for some time risen after the sun or with him, remaining however invis ible, owing to his beams, will at length rise a sufficient length of time before him to be seen. When it does so, this is called its heliacal rising, or it is said to rise heliacally. As in bygone ages the prece ion of the equinoxes has made various stars in succe ion rise heliacally, a means, of which Sir Isaac Newton made use, is afforded of computing ancient dates, in cases in which observers have accurately recorded which star in any year rose heliacally. "The cosmical ascension of a star we term that, when it ariseth together with the sun, or the same degree of the ecliptic wherein the sun abideth; and that the heliacal (ascension), when a star which before for the vicinity of the sun was not visible, being further removed, beginneth to appear."- Browne : Vulgar Errors , bk. iv., ch. xiii. heliacal-year, s. Astron.: The same as CANICULAR YEAR (q. v.). hě li-a-cal-ly, adv. [Eng. heliacal; -ly.] In a heliacal manner. "Heliacally, that is, its emersion from the rays of the sun."-Browne: Vulgar Errors, bk. iv., ch. xiii. hěl-i-ăn-the-mum, s. [Pref. heli- (q. v.), and Lat. an the mum; Gr.an the mon, the same as anthos =a flower.] Bot.: Rock-rose, a genus of Cistacese (q. v.). It contains herbs or under-shrubs, with five petals; stamens, as a rule, many; an imperfectly three celled capsule, with many seeds. About thirty species are known, in Europe, West Asia, and this country. Sir Joseph Hooker divides the genus into three sub-sections: Helianthemum proper, Turberaria, and Pseudos-cistus. The leaves are opposite, entire. It had once some reputation as a vulnerary. Above a hundred and thirty species are cultivated in gardens.