HELIOGRAVURE 



HELIOTROPI8M 



(it-Ill, as liming tin- I'.iili-li campaign in Afghan- 

 istan in IMSO. I i iiiiiiiiuii(l's uiiil Begote's helioctate, 

 ami tlio heliographs (diHering in details) of Mance 

 ami Anderson, an? favniral>ly known. Tin* name 

 heliostat was originally used of an Equatorial 

 ii|.v.) revolving on UH jMilar axis. Heliotrope was 

 tin- name -IM-H to a mirror placed at the distant 

 Mai ion, ami adjusted hy clockwork, so that at a 

 particular hour of the day (arranged beforehand) 

 tin- light of the sun shall he reflected from tlie 

 mirror directly to the surveyor's station. See 



S|i;\ M.UNO. 



Heliogravure. SIM- PIIOTOUKAVURE. 



IIHioiurlrr ('sun-measurer') is an instru- 

 ment invented hy Savery and Bouguer in 1743-48, 

 by means of which the diameters of the heavenly 

 bodies can be measured with great accuracy. As 

 improved hy Dollond, the object-lens of the instru- 

 ment is in two halves, each of which will form a 

 perfect image in the focus of the eyepiece ; and the 

 images may he made to diverge, coincide, or over- 

 lap each other, by varying the distance between the 

 half-lenses. If the diameter of the sun is to be 

 measured, the two lenses are adjusted so that the 

 image* may touch each "other; then the distance 

 between the centres of the two object-glasses 

 measured in seconds gives the diameter of the 

 sun. I'Yauuhofer made many remarkable improve- 

 ments on the heliometer. 



Ileliopolis ('city of the sun'), the Greek 

 name of the city called by the Egyptians On, An, 

 stood on the east side of the Pelusiac branch of the 

 Nile, near the apex of the Delta, and was one of 

 the most ancient and important of Egyptian cities. 

 It was the chief seat of the wisdom of tlie Egyptians, 

 and Thales, Plato, and Solon are reported to have 

 learnt from its priests. Manetho, the historio- 

 grapher of Egypt, was chief-priest here, an office 

 filled centuries earlier by the father-in-law of the 

 Hebrew Joseph. One of the red granite obelisks 

 long famous as Pharaoh's Needles is still standing 

 near the hamlet of Matareieh, 8 miles N. of Cairo. 

 It is 70 feet high, and bears the name of Usurtesen 

 I., the second king of the twelfth dynasty. The 

 ol>elisk called 'Cleopatra's needle,' brought in 1878 

 to England, and that taken to New York in 1880, 

 were originally brought to Alexandria from this 

 city. For the Syrian Heliopolis, see BAALBEK. 



Helios the Greek name of tlie sun ( the Roman 

 Sol], who was worshipped as a god. According to 



Homer, he was a son of the Titan Hyperion and 

 of Theia, and a brother of Selene or Eos. He is 

 described by the same poet as giving light both to 

 g<>, Is and men. He rises in the east, from the 

 marshy borders of Oceanus, into whose dark abysses 

 he also sinks at evening. The later poets, now- 

 ever, gave him a splendid palace in the east, some- 

 where l>elo\v Colchis, and describe him as being 

 conveyed, after the termination of the burning 

 labours of the day, in a winged boat of gold, along 

 the northern coasts of the sea back to Colchis. 

 After the time of yEschylus, he began to be identi- 

 lie.l with Apollo or Pluebns, but the identification 

 was never complete. His worship was widely 

 -1 >read. He had temples in Corinth, Argos, Tro> 

 /ene, Elis, and many other cities, but his principal 

 seat was Rhodes, where a four-team was annually 

 sacrificed to him. The island of Trinacria (Sicily ) 

 was also sacred to Helios, and here his daughters, 

 Phoatusa and Lampetia, kept his flocks of sheep 

 and oxen. It was customary to offer up white 

 lam bs or boars on his altars. The animals sacred 

 to him were horses, wolves, cocks, and eagles. 



Helioscope* a telescope for observing the sun 

 without injury to the eyes, by means of blackened 

 glass or mirrors that reflect only a part of the 

 light. 



Heliotrope (lldwtrapium), a genu* of plant* 

 of the natural order Boraginea? (q.v.); of the 

 section, sometimes made a distinct order, Ehret- 

 iace.-e, the fruit separating only when ripe into 

 four carpels. Many of the speciea have fragrant 

 flowers. The Peruvian Heliotrope (U. Peruvi- 

 <m a in), a shrub with oblong-lanceolate wrinkled 



Common Heliotrope ( Helwtropiam Europceum). 



leaves and small lilac-blue flowers, is in almost 

 universal cultivation for its fragrance, which re- 

 sembles that of vanilla or cherry-pie. Many seminal 

 varieties of this species are cultivated in gardens. 

 They delight in rich light soil, and are propagated 

 by cuttings of the young growing shoots in a moist 

 warni atmosphere. The European or Common 

 Heliotrope (H. Europium), a native of the south 

 and west of Europe, is an annual with small white, 

 or rarely pale red, flowers. Large quantities of 

 the flowers are used by perfumers for making 

 scents. Classical fable accounts for the name 

 heliotrope (Gr. helios, 'the sun,' and trepo, 'I 

 turn') by representing Clytia as turned into this 

 flower through ga/ing at Apollo. 



Heliotrope, or BLOODSTONE, a variety of 

 chalcedony or of jasper, of a green colour with red 

 spots. The finest heliotropes consist of chalcedony, 

 and are translucent, at least at the edges ; the 

 jasper bloodstones are opaque. Heliotrope is found 

 in many parts of the world, as in Scotland, but the 

 finest specimens of this mineral are brought from 

 the southern parts of Asia. It was well known to 

 the ancients, who obtained it chiefly from Ethiopia 

 and Cyprus. It is much used for boxes, seals, \c. : 

 and those specimens are most valued which possess 

 most translucency, and in which the red spots are 

 bright and well distributed. It was much used in 

 the early ages of the Christian church for the 

 engraving of sacred subjects, the figures being so 

 managed that the red spots should represent drops 

 of blood. The name heliotrope (Gr. helios, 'the 

 sun ; ' trope, ' a turning ' ) seems to have been given 

 to this mineral l>ecause when immersed in water in 

 the face of the sun it was said to make the image 

 of that luminary in it appear of a blood-red colour. 

 The heliotrope, thus described by Pliny, must have 

 shown very large spots or veins of red. 



Heliotrope* an instrument. See HELIO- 



ORAPHY. 



Heliotropism ('turning towards the sun'). 

 When a seedling plant is placed in a transparent 

 vessel of water within reach of the light of a window, 

 the stem and leaves gradually bend towards, and the 



