HEM 



HEP 



into two hemispheres, distinguished by 

 the epithets upper and lower. .See GLOBE 

 and SPHERE. 



The centre of gravity of an hemisphere 

 is five-eighths of the radius distant from 

 the vertex. 



HEMISPHERE is also used to denote a 

 projection of half the terrestial globe, or 

 lialf the celestial sphere, on a plane, and 

 frequently called planisphere. 



HEMISTICH, in poetry, denotes half 

 averse, or a verse not completed. 



Of this there are frequent examples in 

 Virgil's JEneid ; but whether they were 

 left unfinished by design or not is disput- 

 ed among the learned ; such are, " Ferro 

 accincta vocat," JEn. II. v. 614. And 

 " Italiamnon sponte sequor," JEn; I.V. v. 

 361. 



HEMP. See CANNABIS. 



The cannabis stativa, or hemp-plant, is 

 cultivated on account of its external fila- 

 ments, which constitute the hemp used 

 for cordage, canvass, cloth, &c. and the 

 seeds abound with oil. This plant is an- 

 nual ; it rises quick into a tall slender 

 Sort of shrub ; its leaves, growing by fives 

 or sixes from the same pedicle, are a lit- 

 tle jagged, and yield a strong smell, 

 which affects the head. The culture and 

 management of hemp makes a consider- 

 able article in agriculture, requiring di- 

 vers operations, as pulling, watering, 

 beating, and swingling. It is sown in 

 May, in a warm, sandy, rich soil ; and is of 

 itself sufficient to destroy weeds on any 

 ground. The first season for pulling 

 hemp is usually about the middle of Au- 

 gust, when they begin to pull the male 

 plants, called fimble hemp. But the safer 

 method is to pnll it a fortnight or three 

 weeks later, when the male plants have 

 fully shed their farina, without which the 

 jeeds will prove only empty husks. At 

 the second pulling, a little after Michael- 

 mas, the' female plants, called karle hemp, 

 are taken out of the ground. This karle 

 hemp is laid in the sun to dry, and then 

 housed, for the seed to be thrashed out. 

 The female hemp alone produces seed to 

 perpetuate tfie kind. The operations of 

 barling, watering, breaking, swingling, 

 and heckling hemp, are very much like 

 those practised in the dressing of flax. 

 The hemp imported into this country 

 chiefly comes from Russia. Amongst it 

 the Riga hemp deserves the preference, 

 which, according to the quality, is divided 

 in rhyne, outshot, pass, and codilla hemp. 

 The Italian, known in this country by the 

 name of Bologna hemp, is of very prime 

 quality, but comes too dear for the con- 

 sumption of the northern parts of Europe, 



The best hemp should be clean, soft, 

 tender, of long staple, and a sound pa- , 

 lish-yellow colour, nether green nor* 

 red. 



HEMIPTERA, half-winged, in natural 

 history, the second order of insects, ac- 

 cording to the Linnxan system. In this 

 tribe the upper part of the wing-sheatha 

 is of a rough or leathery texture ; the 

 lower part is membranaceous. Some- 

 times almost the whole wing-cover is 

 leathery, but of a softer texture than the* 

 coleoptera. Grashoppers, locusts, and| 

 the cicadse, are contained in this division\ 

 The wing-covers in this order cross each, 

 other when closed, instead of meeting in 

 a direct line. This order contains the 

 following genera : 



Aphis 



Blatta 



Chermes 



Cicada 



Cimex 



COCCUB 



Fulgora 



Pneumora 



Thirips 



Mantis 



Nepa 



Notonecta 



Gryllus 



Macrocephalus 



HENDECAGON, in geometry, a figure^ 

 that hath eleven sides, and as many an- 

 gles. 



HEPAR sulplmnis, liver of sulphur, a* 

 combination ot alkali and sulphur. See 



SULPHUIIET. 



HEPATIC, in medicine and anatomy, 

 any thing belonging to the liver. 



HEPATIC gas, the old name for sulphu 

 retted hydrogen. 



HEPIALUS. See PHALEITA.. 



HEPTACHORD, in the ancient poetry, 

 signifies verses that were sung or played 

 on seven chords, that is, on seven differ- 

 ent notes. In this sense it was applied to 

 the lyre, when it had but seven strings. 

 One of the intervals is also called an hep- 

 tachord, as containing the same number of 

 degrees between the extremes. 



HEPTAGON, iin geometry, a figure 

 consisting of seven sides, and as many an- 

 gles. In a regular heptagon, the angle at 

 the centre is = 513. ; the angle of the 

 polygon is =3 128?.. The area is = the 

 square of one of the sides multiplied by 

 3.6339, or if a equal the side, the area = 

 a* X 3.634 nearly = a 1 X &, where t is 

 the tangent of 64|, = half the angle o? 

 the polygon. 



In fortification, a place is termed an 

 heptagon, that has seven bastions for its 

 defence. 



HEPTAGONAL numbers, in arithmetic, 

 a sort of polygonal numbers, wherein the 



