Page:Cyclopaedia, Chambers - Volume 2.djvu/229

 MOO

C *8o)

MOO

near the Moon's Body 5 and rarer above. Now as the Air which incompaffes our Earth is fuch a Fluid, it is manifeft there is Air about the Moon -, and fince the different Denfity of the Air depends on its different Gravity and Elafticity, no doubt the different Denfity of the Lunar Air has the fame Caufes. Again, we have obferv'd the Lunar Air is not always equally clear and tranfparent : fometimes

believed, at the fame time, very remote.we naturally judo« it mull: be very large, to appear under fuch an Angle at fuch a diitance. And thus a pure Judgment of the Soul makes us fee the Moon bigger in the Horizon, than in the Meridian ; notwithstanding its Image painted on the Retina is lefs in the former Situation than the latter. This Hypothefis, F. Gottye deltroys, by obferving that the

changes the fphcrical Figures of the Stars into Ovals j and narrower and more confined the fenfible Horizon is, the in the feveral total Eclipfes jufl mentioned, there was greater does the Moan appear ; the contrary of which obferved a trembling in the Moon's Limb, immediately ihould happen on the Principle laid down, before immerfion, with an Appearance of thin, light Gafjcndi is of opinion, that the Pupil of the Eye, which Smoak flying over it during immerfion, very apparent in is always more open as the Place is more dark 5 being more England. And hence, as thefe lame Phenomena are ob- fo in the Morning and Evening than at other times, by ferved in our Air when full of Vapours, it is pretty plain, reafon the Earth is covered with grofs Vapours 5 and be- at the time when thefe Phenomena are obferved in that of fides, being obliged to pafs through a longer Column or the Moon, it is full of Vapours and Exhalations. And, Series of 'em, to reach the Horizon, the Image of theiWeo« laltly, fince at other times the Lunar Air isclear and tranf- enters the Eye at a greater Angle, and is really painted

parent, producing none of thefe Phenomena, the Va- pours mult have been precipitared on the Moon ; and there- fore either Dew, or Rain, or Snow have fallen.

7. The Moon is a Body in all refpeBs like our Earthy and Jitted for the fame pttrpofes. For we have /hewn that it is

Detife Ofake has Mountains tx\\&. Valleys—- Seas, with

ljlands, TeiunfuU, Rocks* and Promontories-*- *— a changeable Atmofphere, wherein Vapours and Exhalations rife and fall ■ " ■ Day and Night ; a .Saw to illumine the one, and a Moon the other, Summer and Winter, &c.

From thefe, hy Analogy, may infinite other Properties and Appendages of the Moon be deduced : From the

here greater.

In anfwer to which, it muil be faid, that notwithstanding this dilatation of the Pupil, occafion'd by the Obfcurity j if the Moon be viewed through a little pin-hole made in a Paper, /he appears lefs when in the Horizon,

F.Gauye finding both the Conjectures falfe, advances a third : He is of opinion then, when the Moon is in the Horizon 5 the neighbourhood of the Earth, and the grofs Vapours wherewith the Moon then appears invelopcd, have the fame Effect:, with regard to us, as a Wall, .or o- ther denfe Body placed behind a Column ; which in that Cafe appears bigger than when infulate, and incom palled

Changes in the A tmofphere will follow Winds, and other on all fides with an illumined Air. Further, it is obferved

that a Column when fluted, appears bigger than before, when it was plain ; the Flutes being fo many particular Objefts, which by their Multitude occafion the Mind to imagine the whole Object whereof they are compofedof a larger extent. The fame thing may be faid of the feveral Objects feen towards the Horizon, to which the Moon cor- refponds at her Rifing and Setting. And hence it is that /he appears greater itill, when /lie rlfes or fets betweea Trees 5 the narrow, yet diltinct Intervals whereof have

Meteors ■-, and according to the different Seafons of tin year, Rain, M'jts, Frajt, Snow, &c. From the Inequali- ties upon the Moojz's Surface will arife Lakes, Rivers, Springs, 2?c.

Now Nature, we know, produces nothing in vain : Rains and Dews fall on our Earth to make Plants vegetate ; and Plants take Roor, grow, produce Seeds and Fruits for Ani- mals to feed on. But Nature is {till uniform and confident with herfelf, and like things ferve for like Ends ; Why

then may not there be Flams and Animals in the Moonl the fame Effect with regard to the apparent Diameter of

To what other purpofe fonice a Provifion for them ?

Thefe Arguments will receive new force when we come to /hew that our Earth itfelf is a Planet; and that when viewed from the other Planets, it appears, in fome, like the Jtfoon ; in others, like Venus ; in others, Jupiter, &c. A Simi- litude between the Planets, both Optical and Phyfical, be- ing a ftrong Prefumption their Furniture is alike. See Earth and Planet.

To meafure the Height of the Mountains of the Moon.

Suppofe ED (Fig. 19.) the Moon's Diameter, ECD „ ,.,..,.,..,

the Boundary of Light and Darknefs ; and A the Top of and divide the Produa by 5 ; the Quotient gives the Hour'

the Hill in the dark part beginning to be illumined: and the Remainder multiplied by 12, the Minute. If her

WithaTclefcope obferve the Proportion fof A E, or the Age exceed 15, fubftract 15, and proceed with the Re-

diitance of A from the Line where the Light commences, ma inder as before.

to the Diameter of E D : Here we have two fides of a To find the Time of the Moon's beginning tofoine. Mul-

reftangled Triangle A E, CA; the Squares of which tiply her Age, if under 1 5, by 48 j and divide the Product

added together give the Square of the third 5 whence the by 60 : the Quotient gives the Hours • and the Remainder

Semi-diameter CD being fubltraaed, leaves A B, the the Minutes. If her Age be above 15 Days, fubftradr.

Height of the Mountain. t he t j me thus found, from » 4 3 the Remainder gives the time

Rtcciolus,-v,g. found the Top of the Hill St, Catherine of /hining in the Morning, illumined at the diitance of ^ of the Moon's Diameter from the Confines of Light.

the Moon, as a greater number of Flutes with regard to the Shaft of a Column.

For the Eclipfes of 'the Moon, fee Eclipses.

For the Moon's Parallax, fee Parallax.

Tofindthe Moon's Age, To the Day of the Month add the Epaaof the Year, and the Months from March inclu- five. The Sum, if under 30 5 if over, the Excefs is the Moons Age. If the Month have but 30 Days, the Excefs above 29 is the Moon's Age.

To find the Time of the Moon's being in the Meridian, ot Southing: Multiply her Age, if under 1 5 Days, by 4 1

Suppofing, therefore, C E, 8 and A E, 1 5 the Squares of the two will be 6$, whole Root is S.cCz the length of A C 5 fubilra&ing therefore BC=8, the Remainder is AB = o.a The Moss's Semi-diameter, therefore, is to the Mountain's height as 8 is to 0.62 j i.e. as 800 to 62. Suppofing, therefore, the Diameter of the Moon 11"

MOOR, Mora, a Heath, or barren Tract of Ground. See Heath,

It is fometimes alfo ufed for a Morafs, Mofs, ox Fen. See Morass.

Mora Muffa, in antient Writings, particularly denotes a Mofs, or Peat-Mofs.

MOORING, at Sea, is the laying out of Anchors, in a,

Aoon 1 1 8a Englijh Miles, by the Rule of proper place, for the fecure Riding of a Ship. See

Three we find the height of the Mountain 9 Miles. Anchor.

The Heights, &c. of the Lunar Mountains being mea- To Moor a-crofs, is to lay out one of the Anchors on one

furable, Aitronomers have taken occafion to give each its fide, ora-thwart a River, and the other right againft it.

Name. Ricctolus, whom molt others now follow, diitin- ToMoor alongfi, is to have an Anchor in a River, and a

guifhed them by the Names of the Celebrated Afironomers 5 Hawfer on Shore.

and by thefe Names they are {till expreffed in Obfervations of the Lunar Eclipfe, &c. See the Figure, (Tab. Astro- nomy, Fig. s.o.)

The apparent Magnitude of the Moon. The Magnitude of the Moon, at rifing and fetting, is a Phenomenon that has extremely embarratTcd the modern Philofophers. According to the ordinary Laws of Vifion,it ihould appear the leaft when neareft the Horizon, as being then neareft to the Eye -, and yet we find the contrary true

>t, is to moor Quartering, between

To Moor Quartsr-J the two firltways.

Mooring for Baft, Wcft,$$c. is when they obferve which way, and on what Point of the Compafs the Wind or Sea is molt likely to endanger the Ship, and there lay out an Anchor.

MOORS-HEAD, in Chymiftry, a Copper-Cap made in form of a Head, to be let over the Chimney of a Re- verberating Furnace. See Reverberatory.

Moors-Heal is alfothe Head of a Copper or Glafs- ,nfaa. Des Cartes, and from him Dr. Walks, and molt Still or Alembic, which is luted on to the Body or Cucur- other Authors account for this from the long Series of Ob- bit, and hath a Beak or Pipe to let the Spirit run down into ■ ]e as interpofed between the Eje and the Extremity of the the Receiver.

fenfible Horizon, which make us imagine it more remote MOOT, a difficult Cafe, or Queftion argued by the than when in the Meridian, where the Eve fees nothing in Students of Inns of Court, by way of Exercife. Sea the way between the Object and itfelf. This Idea of a Mooting

great difiance makes us imagine the Moon the bigger : The Word is formed either from the Saxon, Mooting Tor any Object being feen under any certain Angle, and Affembly 5 or the French, Mot, Word,

MOOTING,