620 HELIOSCOPE HELLAS ous other places. The sacrifices offered to him were rams, boars, bulls, goats, lambs, white horses, and honey. Among the animals sacred to him the cock was preeminent. Helios was usually represented as riding in a chariot drawn by four horses. HELIOSCOPE. See TELESCOPE. IIELIOSTAT, and Heliotrope, instruments used by surveyors for rendering distant stations vis- ible. The heliostat was invented by 's Grave- sande about 150 years ago, and consists of a mirror turned by clockwork in the pathway of the sun, in such a manner that it will re- flect his rays in a certain direction. A mirror of only one inch diameter can be seen eight miles, and appears as a brilliant star at a dis- tance of two miles. The heliotrope is simply a mirror fixed permanently at a station so as to throw its rays to another station, or always in one direction. This requires of course that an observation should be taken at a certain moment, as the direction of the reflected beam is constantly changing. For most observations the latter instrument answers all the purposes of the former, and is much less expensive. HELIOTROPE (heliotropium, Linn.), the name of annual or perennial plants belonging to the natural order ~boraginacece. H. curassamcum is a smooth annual found in Virginia, Illinois, and southward. H. Europceum occurs sparingly in the southern states as an introduced weed. The species in cultivation are H. Perumanum and H. corymbosum ; these have woody stems, ob- long hairy leaves of a pale green color, and terminal, branching flower stalks. The pleas- antly fragrant flowers are small, but they grow compactly in the recurved spikes. The corolla lleaotrope. is intersected at its mouth with five folds, and is of a purple-lilac color, with a greenish white throat. The principal difference be- tween the two species is that the last named has larger, darker colored, and less strongly scented flowers. Numerous seedling varieties have been .raised, chiefly distinguished by the tint of the corolla, a yellowish or pure white throat, or else by the greater size of the spikes or "trusses." Heliotropes are readily propa- gated from cuttings of tender shoots, and great numbers are raised annually by florists for sale as bedding plants; though it is a shrub, small plants from the unripe wood will flower freely. Plants for the greenhouse may be trained as standards or pyramids, or they may be trained to the wall of a greenhouse ; thus treated they will grow 4 or 5 ft. high. The odor of the heliotrope is compared by some to that of vanilla ; in England it is frequently called " cherry pie " on account of its fra- grance. Pliny and Dioscorides assert that the flowers of the heliotrope turn toward the sun, whence its ancient and generic name. For the same reason it has also been called turnsole and girasole. False heliotrope (Tournefortia Tieliotropioides) is a garden annual, with flow- ers closely resembling those of the heliotrope in everything except odor ; the plant when bruised is disagreeably scented ; in some south- ern gardens where it has been raised for orna- ment it has established itself as a weed. In- dian heliotrope (JieliopJiytum Indicum) is a coarse hairy annual with much the aspect of a heliotrope, which has been introduced from In- dia, and is found in waste places in Illinois and southward. HELIX (Gr. e^f, a whorl or coil), in archi- tecture, a spiral winding around a central axis, according to some authorities without ap- proaching it, in which case it would be desig- nated a spiral. The little volutes under the flowers of the Corinthian capital are also called helices. In electro-magnetism, a helix is a coil of wire wound around any body which is to be magnetized by the passage of the electric cur- rent through the wire. The power is increased with the number of turns, the wire being in- sulated, so as to prevent lateral discharge, by winding cotton thread about it. HELIX, in conchology. See SNAIL. HELL, Maximilian, a Hungarian astronomer, born in Schemnitz, May 15, 1720, died in Vi- enna, April 14, 1792. At 18 years of age he entered the society of Jesus, and in 1745 was made assistant astronomer at the observatory in Vienna belonging to the order, and keeper of the museum of experimental philosophy. In 1751 he took holy orders. Subsequently he filled the chair of mathematics at Klausenburg in Transjlvania for four years, and in 1756 was appointed astronomer and director of the new observatory in Vienna. In April, 1768, he un- dertook a journey to Vardohuus in Lapland to observe the transit of Venus, June 3, 1769, in which he succeeded perfectly, and returned to Vienna in August, 1770. His chief work is a series of Ephemerides, commenced with Ephemeridcs Anni 1757 ad Meridianum Vin- dobonemem Calculi* definite, continued to the year 1791 (35 vols. 8vo, Vienna). HELLAS. See GEEECE.
