Page:Cyclopaedia, Chambers - Volume 1.djvu/989

 HEM

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HEM

HEMIOLUS, an anticnt Mathematical Term, occurring chiefly in Mulical Writers. — It flgnifies the Ratio of two Things, whereof the one contains the other once and an half; as 3:2, or 15 : 10. See Ratio.

Macrobius, on the Somnium SCipionis, L. II. C. r. ob- ferves, that the Concord, call'd in the antient Mufie Hiapente, and in the Modern a Fifth, arifes from this Proportion. Sec Fifth.

The Word is compounded of v^i, half, and 0*©", whole.

HEMIOPE, or Hemiopus, a Mufical Inftrument in Ufe among the Antients. See Music.

The Hemiopus was a Flute with only three fmall Holes. See Flute.

The Word is compounded of M(*l, and lirti, Hole. HEMIPLEGIA, or Hemiplexia, in Medicine, a Palfy of one whole Side of the Body. See Pals* and Paralysis. ■

The Word is compounded of \t.i y half, and irhnosm, I ftrike, or feize.

HEMISPHERE, Hemispherium, in Geometry, is one half of a Globe, or Sphere, when divided into two by a Plane pafling thro' its Centre. See Sphere.

If the Diameter of a Sphere be equal to the Diftance of the two Eyes ; and a right Line drawn from the Centre of the Sphere to the middle of that Diftance, be perpendicular to the Line which joyns the Eyes : The Eyes making a Rotation on the Axis, or middle Point between them, will fee the whole Hemifphere. — If the Diftance of the Eyes be either greater or leffer than the Diameter of the Sphere ; in making fuch Rotation they will view reflectively more or lefs than a Hemifphere. See Vision.

The Writers in Opticks demonflrate, that a Glafs He- mifphere unites parallel Rays at the Diftance of a Diameter, and one third of a Diameter from the Pole of the Glafs. See Lens, Parallel, 13c.

The Centre of Gravity of a Hemifphere is five Eights of the Radius, diftant from the Vertex. See Centre.

Hemisphere, in Afl ronomy, is particularly ufed for one

half of the Mundane Sphere. See World, Astronomy, CSV.

The Equator divides the Sphere into two equal Parts,

call'd the Northern and Southern Hemifpheres. See

Equator.

The Northern Hemifphere, is that half in whofe Vertex is the North Pole. — . Such is that reprefented by D P A, Cfab. Aftronomy Fig. 52.) terminated by the Equator D A, and having the Pole P in its Zenith. See Pole and North. The Southern Hemifphere, is that other half D QA, terminated by the Equator D A ; and having the South Pole Qin its Zenith. See South.

The Horizon alfo divides the Sphere into two Hemi- fpheres, upper and lower. See Horizon.

The Upper Hemifphere is that half of the Mundane Sphere H Z R, terminated by the Horizon H R, and hav- ing the Zenith Z in its Vertex. See Zenith.

The Lower Hemifphere, is that other half H M R, terminated by the Horizon H R, and having the Nadir N in its Vertex. See Nadir.

Hemisphere, is alfo ufed for a Map, or Projection, of half the terreftrial Globe, or half the Celeflial Sphere, on a Plane. See Map and Projection.

Hemifpheres, are frequently called Planifpheres. See Planisphere.

The Word is compounded of npi, half, and <sfM&, Sphere, or Globe.

• HEMISPHEROIDAL, in Geometry, fomething that approaches the Figure of a Hemifphere, but is not juftly fo. The Cacao opens when yellow and ripe, into two large Hemifpheroids, three Foot in Diameter. Freezier. HEMISTICH, in Poetry, half a Verfe. See Verse. 'Tis difputed, whether or no the Hemiftichs, left in the JEneid, were left with Defign ; or whether they are owing to the Work's being unfini/h'd.

In Englifi, &c» the Common and Alexandrine Vcrfes,

require a Reft at the End of each Hemifiich : Common

Verfes at the End of four Syllables; and Alexandrine at the

End of fix. SeeVERSE, Pause, Rest, Alexandrine, G?c.

Leonine Verfes rhime both at the End and at the

Hemiftich. See Leonine, Rhyme.

The Word is compounded of n[ti } half, and sr^©, Verfe,

HEMITONE, in the antient Mufic, was, what we now

call an half Note or Tone. See Note and Tone.

HEMITRITjEUS, in Medicine, an irregular, intermit- ting Fever, which returns twice every Day ; by which it is diitinguifh'd from the §>iiotidian, which only returns once in the Day. See Fever.

The Word is compounded of »/«, half, and TaraT©-, third.

HEMLOCK, Cicuta, a Narcotic Plant ; of fome Ufe 'in Phyfic, in that Intention. See Narcotic.

' There is a Plafter denominated from it in the College Difpcnfatory ; confiftihg of the juice of the Plant boiled up with Gums, &c.

The Common Hemlock is a Poifon ; tho' not of the violent Sort. — We have Inftances of confiderable Quanti- ties being taken without the lead Diforder. Philofoph. IranfaS. N°. 231. See Poison.

The Cicuta fo much celebrated among the Antients was the Juice of a Species of this Plant, call'd Oenanthe Aquatica. See Cicuta.

HEMP, a Plant of great Ufe in the Arts and Manu- factories ; furnifliing Thread, Cloth, Cordagej &c. See Thread, £Tc.

Hemp, by Naturalifts call'd Cannabis, bears a lieaf Analogy to Flax, Linum ; both in refpeft of Form, Cul- ture and Ufe. See Flax.

The Plant is annual ; that is, muft be fown a-frefK every Year. — . It rifes quick, into a tall, flender Sort of Shrub, whofe Stem however is hollow, and big enough to be charr'd, and thus ufed in the Compofition of Gun- Powder. — Its Leaves arife by fives or fixes from the fame Pedicle, and are a little jagged; yielding a ftrong Smell, which affects the Head. ' — Its Flowers grow grape-wife, oppofite to each other, in Manner of a St. Andre-id's Crofs; each confifting of five yellowifh Stamina, incompafs'd with a like Number of Petala, purple without, and white within. — Its Fruit, or Seed, is fma.ll, ,and round, fill'd with a white folid Pulp; and grows' on the Top of the Stem.} having its Pedicles diffinct from thofe of the Flowers. — Laftly, its Bark is a TifTue of Fibres, joyn'd together by a foft Matter, which eafily rots it.

Hemp is of two Kinds ; Male, popularly call'd Karl 5 and Female, or Fimble. — 'Tis the Male alone that produces Seed, to perpetuate the Kind : From the Seed of the! Male arifes both Male and Female.

It does not appear, that the Antients were acquainted- with the Ufe of Hemp, in refpefl of the Thread it affords. 'Pliny, who fpeaks of the Plant in his Natural Hijlory, L. XX. C. 23. fays not a Word of it; contenting himfelf with extolling the Virtues of its Stem, Leaves and Root. In Effect, what fome Writers of the Roman Antiquities remark, via. that the Hemp, neceffary for the Ufe of War, was all ftored up in two Cities of the Wefem Empire, viz. at Ravenna and Vienna, under the Direction of two Procurators, call'd Procuratores Linificii ; muft be underftood of Flax.

The Seed is faid to have the Faculty of abating Vene- real Defires ; and its Decoction in Milk, is recommended againft the Jaundice, SSc. — The Leaves are held good againft Burns, and the Juice thereof againft Deafncfs. ■ — ■ The Powder, or Flower, mix'd with any ordinary Li- quor, is faid to turn thofe who drink thereof, flupid.

The Culture and Management of Hemp, makes a confider- ablfeArficle in Agriculture; there being divers Operations requi- red therein, as Pulling, Watering, Seating, Swingling, &c. The Plant is fown in May, in a warm, fandy, rich Soil ; and is it felf fumcient to deftroy Weeds on any*" Ground. — About Lammas they begin to gather it ; the Light or Female being firft ripe. The Marks of its Ma- turity, are its Leaves turning yellow, and the Stalks whites The Way of gathering, is to pull it up by the Roots; after which they bind it up in Handfuls or Bundles : The Male they let ftand eight or ten Days in the Air, that the Seed may dry and ripen ; after which they cut off the Heads, and beat or thrafli them to get out the Seed. ■ — They alfo beat the Female, to get out a thick fetid Sort of Duft, contain'd therein.

This done, they proceed to water or rate it, by lay- ing it five or fix Days in a Pool, or other ftagnant Water; to rot the Bark. A Stream, or running Water, would do the Bufincfs much better, but that it infects the Water, and gives it a Quality very pernicious to the Health ; for which Reafon it is forbid to rate it in Waters ufed for domeftic Purpofes

When rotted, and taken out again, they dry it ; theri Brake or beat out the dry Bun, or Hex, which is the woody Part of the Stem, from the Rind or Bark which covers it, by crufhing it in a tooth'd or nick'd Inftrumenf call'd a Brake, beginning with the Root End.

When the Bun is fufficiently broke, and hangs by fmall Shivers, they fwingle or beat them out with a Piece of Wood, edged for the Purpofe. — ■ Note, the Karl Hemp they fometimes break with the Fingers, and ftrip off the Rind, without the Help of the 'Brake, or Swingle.

The next Thing is to beat the Hemp ; which is done either on a Block, or in a Trough, with an Hammer* or with Beetles ; till it feel fufficiently foft and pliablej — It remains now- to be heckled, or paffed thro' divers Tooth-Inftruments, not unlike the Wool-dreffers Combs, of different Finenefs : This, feparating the fhorter Tow from it, the reft is fit to be fpun, wove, iSc. for Thread,
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