Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/118

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\t\ their bowels into the fubftance we call wax. Reaumur's Hirt. Inf. Vol. 10. p. 50. See Honey. NEC EARINE, a fruit greatly efteemed for its delicious flavour, and fuppofed to have its name from the nectar of the Gods, in heathen ftories.

It differs in nothing from the peach, but in having a fmoother ikin, and a firmer pulp, See Peach.

We have ten kinds of ne£farine cultivated by the curious in gardening.

1. Faircbild 's early neclarine ; this is a fmall fruit of a red co- lour, and very well tatted, and ripens in July, the earliett of all this kind

2. The Elrugc neclarine ; this is a larger fruit, of a purple co- lour on that lide which was toward the fun, and of a greenifli yellow on the other parts This is a very well flavoured neclarine^ of a foft, melting juice, and parts from the ttone : it ripens toward the end of July.

3- The Newington m >fl 'urine*, this is a fair large fruit, of a fine red toward the fun, and of a yellowifti green toward the wall. It has a very rich juice, but the pulp adheres to the ttone : this ripens in Augutt.

4. The f;ar!et nefiaritie; this is of a fine glowing red toward the fun, and of" a pale red toward the wall ; it ripens in the end of July.

5. The Bn-gnon, or Italian neclarine; this is a fair, large fruit, of a deep red next the fun, but of a foft yellow next the wall, The pulp is firm, and of a rich flavour, but clofcly adheres to the ttone, and is red in that part : this ripens in the middle of Augutt.

6. The Roman red neel mne ; this is a very fair large fruit, of a deep purple toward the fun, and of a greenifli yellow next the wall. The pulp is very firm and well tatted, but it is red ahout the ttone, and adheres firmly to it: this is ripe in the middle of Augutt.

7. The Murry neftarine ; this is a middle-fized fruit, of a dir- ty red next the fun, and of a greenifli yellow next the wall. The pulp is tolerably well flavoured : this ripens in the middle of Augutt.

8. Thegoldeti neclarine; this is afair handfome fruit, of a foft red next the fun, but of a gold yellow next the wall, and its pulp is very yellow, but of a faint red about the ttone to which it adheres : it is a very well-flavoured kind, and ripens at the end of September.

9. Temple's nectarine j this is a very fine kind : it is of a foft red toward the fun, and of a yellowifh green next the wall. It parts from the ttone, and is of a very rich flavour ; the pulp is white in other parts, but yellowifh about the ttone : this ripens in the middle of September.

10. The Peterborough neclarine, called by fome the late, green ne£lwine\ this is a middle-fized fruit, of a pale green colour toward the fun, and of a whitifii green toward the wall ; the pulp Is firm, and well-flavoured: it ripens toward the end of September.

The pruning, planting, and whole culture of this plant is the fame with that of the peach. Millers Gard. Did:. Seethe article Pfach.

NECTARIUM, among botanifls, expreffes what is only a part of the corolla, fometimes, though more rarely the whole. It is a part deftined for the reception of the honey juice of the plant ; and is very various in its figure. Sometimes, it is on- ly a hollow in a petal ; fometimes, it is a little fquamma ; fometimes a tubercle ; and fometimes a plain tube.

NECUIA, in botany, a name given by the antient Greeks to a fpecies of mullein. See Mullein.

The Greeks and Romans both ufed the ftalks of a peculiar kind of mullein, called ihryallis by Nicander. For the making the wicks of lamps, we have a kind of mullein called Ucimites, and candle-wick mullein, from the Tu^Itsj of Diofcorides; but it is not certain that ours is the fame plant.

The antients ufed the ttalks of many different plants for the wicks of their candles, and lamps. I'lie rufh ftripped of its bark was as commonly in ufe with them, as with us, for this purpofe i and they alio ufed the nettle, this mullein, and many other plants, whofe ftalks were compofed of tough filaments, for the fame purpofe ; beating them out like hemp, and when dry, dipping them in melted refin, and other fuch inflammable fubttances. When thus prepared, they were readily inflam- mable, like our flambeaux, and this mullein having ftalks more long, and large, and more firm than all the others, was ufed to make thofe lights with which they fet fire to the funeral pile for confuming the alhes of their dead friends.

NEEDLE {Cycl.) — NEfDLE,in furgery. Jtis to be obferved, that needles of filver pierce more eafily in ftitching arteries af- ter an amputation, than thofe made of fteel. Monro, in Med, Eff- Edinb. Vol. 5. Art. 41.

NEGATIVE {Cycl.) — Negative power, in algebra, is ufed for thofe powers of a quantity which have a negative fign. Thus a— "-' is called a negative power. Negative powers arife from the divifion of any power of a quantity, by a greater power of the

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fame quantity. Thus, ■— g =

1" =«""=- for


 * j t Suppl..

zn a i and in general, =: — . See Power, Cycl

Negative/^. The ufe of the negative fign, in algebra, is at* tended with feveral confequences that at firft fight are admit- ted with difficulty, and has fometimes given occaficn to no- tions that feem to have no real foundation. This fign implies that the real value of the quantity reprefented by the letter to which it is prefixed, is to be fubftracted ; and it ferves with the pofitive fign, to keep in view what elements or parts enter into tbecompofition of quantities, and in what manner, whe- ther as increments, or decrements, (that is, whether by addi- tion or fubttraclion) which is of the greateft ufe in this art. In confequence of this, it ferves to exprefs a quantity of an oppofite quality to the pofitive, as a line in a contrary pofi- tion ; a motion with an oppofite direction; or a centrifugal force in oppofition to gravity; and thus often faves the trou- ble of diftinguifhing, and demonftrating fcparately, the various cafes of proportions, and preferves their analogy in view. ' But as the proportions of lines depends on their magnitude on- ly, without regard to their pofition ; and motions, and forces, are faid to be equal, or unequal, in any given ratio, without regard to their directions ; and, in general, the proportion of quantities relates to their magnitude only, without determinino- whether they are to beconfidered as increments or decrements'; fo there is no ground to imagine any other proportion of — b and -f- a, (or of — 1 and 1 ) than that of the real magni- tudes of the quantities reprefented by b and a, whether thefe quantities are, in any particular cafe, to be added, or fubftracted. It is the fame thing to fubftract a decrement as to add an equal increment, or to fubftract — b from a — b, as to add -f b to it: and becaufe multiplying a quantity by a negative number implies only a repeated fubftract ion of it, the multiplying— b by — - n, is fubftr ailing — b as often as there are units in n ; and is therefore equivalent to adding -f- b fo many times, or ' the fame as adding -f- n b. But if we infer from this, that 1 is to — » as — btonb, according to the rule, that unit is to one of the factors as the other factor is to the product, there is no ground to imagine that there is any myftery in this, or any other meaning than that the real magnitudes reprefented by 1, n, b, and n b are proportional. For that rule relates on- ly to the magnitude of the factors and product, without deter- mining whether any factor, or the product, is to be added, or fubtracted. But this likewife mutt be determined in algebraic computations ; and this is the proper ufe of the rules concern- ing the figns, without which the operation could not proceed. Becaufe a quantity to be fubftracted is never produced in com- pofition, by any repeated addition of a pofitive, or repeated fubftraction of a negative, a negative fquare number is never produced by compofition from the root. Hence ,/ — - 1 or the fquare root of a 7«gv?r/iv, implies an imaginary quantity ;and in resolution, is amark or character of the impoffibie cafes of a pro- blem, unlefs it is compenfated by another imaginary fymbol or fuppofition, when the whole exprefTion may have a real fio-nifi- cation. Thus 1 -f </ — i,and i — </ — 1 taken feparately, are imaginary, buttheirfum is 2 ; as the conditions thatfeparately would render the folution of a problem impottlble, in fome cafes deftroy each othei's effect, when conjoined. In the purfuit of general conclufions, and of fimple forms for reprefentinf them, expreflions of this kind mutt fometimes arife where the imagi- nary fymbol is compenfated in a manner that is not always fo obvious.

By proper fubftitutions, however, the exprefTion may be tranf- formed into another, wherein each particular term may have a real fignification, as well as the whole exprefBon. The the- orems that are fometimes briefly difcovered by t.-e ufe of this fymbol, may be demonttrated without it, by the inverfe ope- ration, or fome other way; and though fuch fymbols are of fome ufe in the computations by the method of fluxions, its evidence cannot be faid to depend upon arts of this kind. See MacLauriffs Fluxions, B. 2. ch. t.

NEGRO [Cycl.) — Mr. Boyle has obferved,- that the heat of climates cannot be the true caufe of the colour of negroes For though the heat of the fun may darken the colour of the flrin, yet experience does not fliew that heat is fufflcicnt to produce a true blacknefs, like that of negroes. In Africa itfelf many nations of ./Ethiopia are not negroes, nor were there any blacks originally in the Weft Indies. In many parts of Afia, under the fame parallel with the African regions, inhabited by blacks, the people are but tawny. He adds, that there are n.groes in Africa, beyond the fouthern tropic, and that a river fometimes parts nations, one of which is black, and the other but tawny. Boyle's Works abr. Vol. 2. p. 42, 44.

Dr. Barrere alledges that the gall of negroes is black, and being mixed with their blood, is depofited between their fk'in, and fcarf fkin. Diff. on the phyf. caufe of the colour of negroes. We have a differtation on this head by Dr. John Mitchell of Virginia, in the PhilofophicalTranfactions, N° 476. Sect. 4. where he advances thefe proportions, and enters into a learned detail to fupport them.

i°. The colour of white people proceeds from the colour which the epidermis tranfmits ; that is, from the colour of the parts under the epidermis, rather than from any Golour of its own.

2°. The fkins of negroes are of a thicker fubftance, and denfer texture, than thofe of white people, and tranfmit no colour through them. 2 3, The