Page:Cyclopaedia, Chambers - Volume 1.djvu/540

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Wound, to moderate the Violence of the Pain, the Flux of Blood, and the Accefs, and Impreflion of the ex- ternal Air.

The Cauterization performed, the Wound is «over d

with Lint and the Eye with a Defective, and

a Triangular Comprcfs. Dionis.

For the firft drcfltng of the Entorfe, Mr. DiomS ufed a little Defenjiiive made of the White of an Egg, Oleum Rofatttm, and Alumn-Powder.

DEFERENS, Deferentia-, in Anatomy, is applied to certain Veffels of the Body, appointed for the Convey- ance of Flumours from one Place to another.

The Vafa DeferentiA, are the Veflels that convey the Seed as fail as it is fecreted, and prepar'd in the Tcfticles, £?c. into the Veficnltf feminales, there to be dc- pofited., till an Emiflton is requir'd. See Seed.

Some call them the Bjaculatory Veffels. They are white, nervous, and round, fituate partly in the Scrotum, and partly in the Abdomen. See Generation.

Deferent, or 'Deferens, in the ancient Aftronorny, a Circle invented to account for the Excentricity, Perigee, and Apogee of the Planets.

As the Planets are found differently diftant from the Earth at different Times, it was fuppofed, that their pro- ber Motion was perform'd in a Circle, or Ellipfis, which is not concentric with the Earth - y And this excentric Cir- cle, or EUipfis, they call'd the Deferens, becaufe paffmg through the Center of the Planet, it feem'd to fupport, or fuftain it in its Orbit.

The Deferens is fuppofed differently inclln'd to the Ecliptic, but in none more than 8 Degrees, excepting that of the Sun, which is in the Plane of the Equator it felf, and is cut differently by the ^Deferents of the other Pla- nets in two Places, call'd Nodes.

In the Ptolomaic Syftem, the fame Deferent is alfo call'd the Deferent of the Epicycle, becaufe it traverfes the Centre of the Epicycle, and feems to fuftain it. See Epicycle, Ptolemaic, &c.

DEFICIENT Numbers, are fuch whofe Parts added tctfcther make lefs than the Integer, whofe Parts they are. E. gr. 8, whofe Quota-Parts are i, 2, and 4, which together only make 7. See Abundant Number.

Deficient Hyperbola, is a Curve of thatDenomi- nation, having only one Afymptote, and two Hyperbolic Legs, running out infinitely towards the Side of the Af- fymptote, but contrary Ways. See Curve.

DEFFA1T, 01- Decapitc, a Term ufed by the French Hera Ids, to denote a Keaft, whofe Head is cut off fmooth 5 in which it differs from Erafed, where it is, as it were, torn off, and the Neck left ragged. Sec Erased.

DEFILE, in Fortification, is a {freight narrow I^ane, or Pafi'age, through which a Company of Horfe, or Foot, can pafs only in File, by making a fmall Front, fo that the Enemy may take an Opportunity to flop their March, and to charge them with fo much the more Advantage, in Regard that the Front and Rear cannot reciprocally come'to the Relief of one another^

Hence, to go off File by File, is caU'd Defiling. The Army began to defile on the left, and was fore'd to defile at each End of the Field, byReafon of the MorafTes, and the Woods. The Word is form'd from the French deffi- ler, to unthread, or unftring.

DEFINITE, in Grammar, is applied to an Article, or a Tcnfe of a Verb, that has a precife, determinate Signi- fication. See Article, Tense, &c.

Such are, the Article the in Englifh, le and la in Trench, &c. which fix, and afecrtain the Noun they be- long to, to fome particular ; as, the*K\r\g, /eRoy; where- as in the Quality, o/King, de'R.oy, the Articles of de, mark nothing precife, and arc therefore call'd Indefinite. Ihave loved, is a c Preter-1 } erfe£i 'Definite. See Verb.

DEFINITION, in Philofophy, Logic, &c. an Enu- meration of the chief fimple Idea's, whereof a compound Idea confiffs 5 in order to afcertain, or explain its Nature, and Character. See Idea.

The Schoolmen give very imperfect Notions of Defini- tion. Some define it the firft Notion, or Conception, that arifes of a Thing, whereby it is difcinguiffi'd from every other, and from which, all the otherTnings that we con- ceive of it, are deduced. But the ufual Doctrine is, Oratio explicans qitod res eft, A Difcourfe explaining what a Thing is : That is, as they further explain it, A Difcourfe conveying thofe Attributes which cjreum- fcribe, and determine the Nature of a Thing. For to ex- plain, is only topropofe the Parts feparately, and exprefs- ly, which were before propos'd conjunctly, and implicitly 5 fo that every Explication has regard to fome Whole.

Hence, according to the divers Kinds of Parts in any Tiling, -viz. Phyfical Parts, Metaphyfical Parts, ££c. arifc fo many divers Kinds of Definitions of the fame.

Thii

ing 5 Thus, Mams euher defined an Animal confix „ - of Soul andSody 5 Or, a re afonable Animal, &c.

Definitions are of two Kmds ; The one Nominal, or, of the Name : The other Real, or, of the Thine

Definition of the Name, or Nominal Definition is that which explains the Senfe, or Signification affected to a Word : Or, as Wolfius more accurately confidcrs ic an Enumeration of certain Marks, or Characters, fuffi- cient to diftinguifh the Thing defined from any other Thing ; fo to leave it out of doubt, what the Subject is intended, or denoted by the Name. Such is the 2)e- finition of a Square, when it is faid to be a quadrilateral equilateral, rectangular Figure.

By Definition of the Name, is either meant a Declara- tion of the Idea's, and Characters affected to the Word in the common Ufage of the Language 5 or the pecu- liar Idea's, ciJ'c. which the Speaker thinks fit to denote by that Word $ /. e. the fpecial Senfe wherein he propofes to ufe it, in his future Difcourfe. For it may be obfer- ved, that the Significancy of any Word depends intirely on our Will 5 and we may affix what Idea we plcafe to a Sound, which it felf fignifies nothing at all. The De- finition of the Name therefore, in the fecond Senfe, is merely arbitrary 5 and ought never to be call'd inQueftion 5 Only 'tis to be minded, that we keep inviolably to the fame Signification. Hence, a Definition comes to ftand, or to be made Ufe of, as an undoubted, or felf-evident Maxim, as it frequently does, and particularly among Geometricians, who, above all other People, make Ufe of fuch Definitions.

Not that we mean, that after having defined a Thing fo and fo, there is nothing in our Idea af- fix'd to the defined Term, but muff be granted to the Thing it felf: Thus, If any one fhould define Heat to be a Quality in certain Bodies, like that which we feel up- on the Application of Fire, orhotBodics- noMancouId find Fault with the Definition, as far as it expredes what he means by the Word Heat 5 but this docs not- hinder us from denying, that there is any Thing in the Body that warm us, like what we feel in our felves.

Definition of a'Thing, or Real Definition, is pro- perly an Enumeration of the principal Attributes of a Thing, in order to convey, or explain its Nature. Thus a Circle is defined a Figure, whofe Circumference is every where e qui dift ant from its Centre,

A good Author, Wolfius, defines a Real Definition to be a diftinct. Notion explaining the Gene/is of a Thing, that is, the Manner wherein the Thing is made, or done : Such is that of a Circle, whereby 'tis laid to be formed by the Motion of a right Line round a fix' 'd 'Point. On which footing, what was before inftane'd as a Real Definition of a Circle, amounts to no more than a nominal one.

This Notion of a Real Definition is very ftricT: and juft j and affords a fulficient Diftinction between a rea? y and a nominal one. But, tho' it has the Advantages of Analogy, Diftinftncfs, and Conveniency on its Side 5 yet, being only it felf a Nominal Definition, i. e. a De- finition of the Term Real Definition^ we mult con- sider it in that Light, that is, as an Idea affix'd arbitra- rily to that Word, and which the Author always de- notes by that Word in the Courfe of his Book. But, in Effect, 'tis not the ufual Senfe, or Acceptation of the Term 5 which is much lefs convenient and diftin£t. And 'tis to that ufual Acceptation we are here chiefly to have regard.

A Definition is ufually divided into accurate, and inaccurate - 7 The firft is what we ftricfly call a Defi- nition 5 The fecond, we diftinguifh under the Name of Defcription. See Description.

Of the Parts enumerated in a Definition, fome are common to other Things befide the Thing defined?, Others peculiar thereto : The firft are call'd the Ge- nus, or Kind ; and the fecond, the Difference. Thus, in the former Definition of a Circle, by a Figure whofe Circumference is every where equidiftant from its Centre: The Word Figure is the Kind, as being a Name com- mon to all other Figures, as well as the Circle : The reft are the Difference, which fpecify, or diftinguifh the Circle from every other Figure.

And hence arifes thatRecipc of Fa. 4e Colonia, for the making of a Definition. Take, fays he, fomething mat is common to the Thing defined with other Things, and add to it fomething that is proper, or peculiar to the Thing 5 and you will have a Definition. Thus, e.gr. Rhetoric is defin'd the Art of Speaking well $ For that it is an Art 9 is common to it with feveral other Things 5 but that it is the Art of.Sfeak.ing well, is peculiar to it alone.

There are three common Rules of a good Definition. Firft, That it be clear, and more eafy and obvious than the Thing defined. Secondly, That it be univerfal, oc adequate to, the Thing defined ^ That is, that it agree

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