Page:Cyclopaedia, Chambers - Volume 2.djvu/224

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thofe Tenfes, or Times, making fome ferve for fimple Affirmations, as love, hved $ and referving the relt for Affirmations that were modified ; as, if he jkould love, might he have loved: yet they kept not iteadily to their Rules, but fornetimes made ufe of fimple Inflexions to exprefs Affirmations that were modified ; as etft vcreor, for etji verear. And it is from this laft kind of Inflection, that Grammarians have formed the Mood they call SubjunBive. See Subjunctive.

But further, befides the Affirmation, the Action of our Will may be taken for a Mode, or Manner of our Thought 5 and Men have found themfelves under a Neccffity of ex- prt-ffing what they will, as well as what they think, Mow we may will a thing in feveial manners ; whereof there are three which may be conlider'd as the Principal. jRr/?, then, We fornetimes will things which don't depend on ourfelves, and in that cafe we only will them by a bare wifii, which the Latins exprefs by the Particle Utiham ; and we by, Fleafe God. Some Languages, as for inltance, the Greek, have invented particular Inflections for this end $ whence the Grammarians have taken occafion to call it the Opta- tive TWWe : And there feems fomething like both in the French, Italian, and fyantjh Tongues, in regard thefe have a kind of triple Tenfes ; but in Latin, Enghjh, &c. the fame Inflections ferve tor the Subjunctive, and for the Optative. For thir, reafon, one may very well retrench this Mode from the Latin Conjugations 5 it being the different Inflections that make Modes, not the different Manner of figoifying, which may be varied to infinity. See Optative.

^e fornetimes will in another manner ; as when we are content it mould pafs, tho' we don't abfolutely defire it ; as when Terence fays, ?rofudat 7 f>erda% A pereat, le:himfpend, fink, perifh. Men might have invented a particular In- flection, to exprefs this Movement, as in Gieek they have done to exprefs a fimple Defire. But they han't done it 5 and in lieu thereof, make ufe of the Subjunctive. In Eng- UJh we add the Particle, Let him fyfnd, £$??. Some Au- thors call this the Potential or Coocefiive Mode.

'\ ne third manner of wilting, is when what we defire, depending on another Peribti, of whom we can obtain it, we fignify our Will that he do it. And this is the Motion we ufe, when we command or pray; and to exprefs this Motion, was invented the Mode we call Imperative 5 which has no fii-fl Perfon in the Singular, becaufe a Man, properly fpeaking, cannot command himfelf: Ir fume Languages it has no third Perfon, becaufe, in flrntnefs, a Man cannot command an) Perfon, but him to whom he (peaks and ad- dreffes himfelt. And in regard rhe Command or Prayer always relates 1 to wnat is :o come, it happens that the Im- perative Mode, and the Future Tenfe, are frequently ufed for each other, efpeciaily in rhe h threw ; as, nan occides, thou fhalt not hill, for do not J/UU Kence fome Gramma- rians place the Imperative among the Number of Fu- tures. See Imperative.

Of all the Modes we have mention 'd, the Oriental Lan- guages have none but the !*• f, which is (he Imperative; and on the contrary, the modern Languages have none of them any particular Inflection for the imperative. The Method we take for it in Englifo, is either to omit the Pronoun, or tranfpofe it ; thus. I love, is a fimple Affirma- tion » Love, an Imperative: He love, an Affirmation 5 Love we, an Imperative.

MOOD, in Philofophy, I M

Mood, in Mufic, 5 hee "° DE -

MOON, Lima, J, in Aftronomy, one of the heavenly Bodies, ufually rank'd among the Planets ; but with more propriety accounted a Satellite, or fecundary Planet. See Planet and Satellite.

The Moon is an Attendant of our Earth, whom /he re- fpeefs as a Centre, and in whofe Neighbourhood fhe is conftantly found ; infomuch as if view'd from the Sun, /he would never appear to depart from us by an Angle greater than ten Minutes. See Earth.

As all the other Planets move primarily round the Sun, fo does the Moon round the Earth : her Orbit is an Ellip- sis, in which Hie is retain'd by the Force of Gravity ; per- forming her Revolution round us in 27 Dayi, 7 Hours, 43 Minutes; which is alfo the precife time of her Rotation round her Axis. See Orbit, and Revolution.

The mean Diftance of the Moon from the Earth, is oci Semi-diameters of the Earth 5 which is equivalent to iio.occ Miles. See Distance.

The mean Excentricity of its Orbit, is rrso of its mean Diflance, which makes a confiderable Variation in that mean Diflance. See Eccentricity.

The Moon! Diameter is to that of the Earth, as 11 to 40.25 or 2175 Miles: Its mean apparent Diameter is 31 Minutes 15-, and that of the Sun 32 Minutes 12 Seconds. See Diameter and Semi-diameter.

TheMoo/t's Surface contains 14,000,000 fquare Miles; ar.d its Solidity 5,000,000,000 cubical ones : The Denfity of the Mao;:'; Body is to that of the Earth, as 48011 to

39214, to that of the Sun as^Son to 10000 : Its Quan- tity or Matter to that of the Earth, nesrly as 1 to 39.15 : and the Force of Gravity on its Surface, is to that on the Surface of the Earth, as 130.2 10407.8. See Solidity, Density, Gravity, £>c.

Thcnomena of the Moon.

The Phamomena or different Appearances, of the Moots, are very numerous. Sometimes flic is mereafmg, then ■warning; fornetimes homed, then/emi circular ; fornetimes gibbous, then fall and globular. See Phases.

Sometimes, again, /he illumines us the whole Night 5 fornetimes only a part of it ; fornetimes fhe is found in the Southern Hemifphere ; (ometimes in the Northern : All which Variations having been firll obferv'd by Endymion, an antient Grecian, who firil watch'd her Motions, he was fabled to have fallen in love with her.

The Source of molt of thefe Appearances, is, that the Moon is a dark, opake, aid fpherical Body ; and only fllines with the Light /lie receives from the Sun : whence only that Half turn'd towards him is illumin'd ; the oppo- site one remaining in its native Datknefs. The Face of the Moon vifible on our Earth, is that part of her Body turn'd towards the Earth ; whence, according to the various Pofi- tions of the Moon with regard to the Sun, and Earth, we obferve different Degrees* of Illumination ; fornetimes a large, and fornetimes' a lefs Portion of the cnlighten'd Sur- face being viiible.

The Fbafes of the Moon. To conceive the Lunar Phafes : Let S (Plate Astro- nomy, fig.13.) reprefent the Sun, T the Earth, RTS a Portion of the Earth's Orbit, and ABCDEFG the Orbit of the Moon, wherein /lie revolves round the Earth, in the fpacc of a Month, advancing from Weft to Eaft : Cinneft the Centres of the Sun and Moon by the right Line SL, and thro the Centre of the Moon imagine a Plane M L N, to pafs perpendicular to the Line S L : the Seflion of that Plane with tho Surface of the Moon, will give the Line that bounds Light and Darknefs, and feparates the illumin'd Face from the dark one. See Illumination.

Connect the Centres of the Earth and Moon by T L, per- pendicular to a Plane P L O, pafling thro the Centre of tho Moon ; that Plane will give on the Surface of the Moon, the Circle that diflingui/hes the vifible Hemifphere, or that towards us, from the invifible one, and therefore call'd the Cncle of ' Vifion. See Circle of Vision.

Whence it appears, that whenever the Moon is in A, the Circle bounding Light and Darknefs, and the Circle of Vifion, coincide : So that all the illumin'd Face of the Moon will be turn'd towards the Earth; in which Cafe, the Moon is with refptct to usfrf, and /liincs the wholeNight ; with refpect to the Sun, fhe is in Ofpofirion ; in regard the Sun and Moon are then feen in oppofite Parts of the Hea- veni, the one rifing when the other fets. See Full Moon and Opposition.

When the Moon arrives at B, the whole illumin'd Disk M P N is not turn'd towards the Earth ; fo that the vifible Illumination will be fhort of a Circle, and the Moon will appear gibbous, as in B. See Gibbous.

When flie reaches C, where the Angle C T S is nearly right, there only one half of the illumin'd Disk is turn'd towards the Earth, and then we obferve a Half Moon, as in C; and fhe is faid to be dichotomized or bijJcBed. See Half Moon and Dichotomy.

In this Situation the Stin and Moon are a fourth part of a Circle remov'd from each other ; and the Moon is faid to be in a quadrate JffeB, or to be in her Quadrature. See Quadratures.

The Moon arriving at D, a fmall part of the illumin'd Face M P N, is only turn'd towards the Earth : for which reafon, the fmall part that fhines upon us, will be feen falcated, or bent into narrow Angles or Horns, as in D. See Falcated.

At lafl, the M>o« arriving at E, /hews no part of her illumin'd Face to the Earth, as in D 5 this Pofition we call the New Moon, and flic is then faid to be in Conjunction with the Sun ; the Sun and Moon being in the fame Point of the Ecliptic. See New Moon, and Conjunction.

As the Moon advances towards E, /he refumesher Horns 5 and as before the New Moon, the Horns were turn'd Weft- ward ; fo now they change their Pofition, and look Eaft- ward : when /he comes at G, /lie is again in quadrate Af- petl with the Sun ; in H gibbous, and in A again full.

Here, the Arch E L, or the Angle STL, contain'd un- der Lines drawn from the Centres of the Sun and Moon to that of the Earth, is call'd the Elongation of the Moon from the Sun : and the Arch M O, which is the Portion of the illumin'd Circle M O N, that is turn'd towards us, and which is the Meafure of the Angle that the Circle bound- ing Light and Darknefs, and the Circle of Vifion, make with each other, is every where nearly fimilsr to the Arch

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