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reprcsented to «s under « fcigger Angtc, and more Distinct, jr tf aecord-ingly apprebended as so much nearer. But the Caile is otherwHe, «vhen wedo not, by the known bignefs, judge the Distance; but, by the supposcdDistance, judge of the Bignefs, as in the Cafe befbre us. ,And accorstingly,different Persons, according to different fanfied Distances, jqdge very dtste-*•Tently.

Again ; in our two Eyes (when the Object is feen by both) there is yctanother means of Estimating bow far off it is. ("And it is this by wbich nvcjudge of Distances.) Natnely, there are, from the sime Object, two düste-rem V-isual Cones, terminated at the two Eyes: whofe two Axes cqptaiu, atthe Object, disterent Angles, according to disterent Distances : An AcuterAngle at a great Distance, and more Obtuse when nearer.

Now, that such Object may be feen by both Eyes clearly; it is rcqpi-c site, that the Eyes bc put in such a Position, as that the Light of each Eyereccive the -refpective Axis at Right Angles^ which reqyires a disterent Posi-tion of the two Eyes, according to the different Distance of the Object ; aswill manifefrly -appear, if \ve Ioqk, with Atteution, on a Finger (or othqrsirnll Object; at two or three Jnches Distance from the Eye; and then upqnanother iike Object at three or four yards beyond it: (and this qlternqvely so-veral times.) For ’twill be manifest, that While we Jpok intently 011 the pne,■we do not fee the other, (or but coitfusedly) though both be just before us.And, as we change our view, from the one to the other, we manifestly feela Motion of the Eyes (by their Musoles) from one Ppsture to ,another.

And according to dic different Pasture in the Eyes, requisite .to a clestrVision by both, we Estimate the Distance of the Object from,ps.

And hence it is, that they whp have Jost the Sjght af one Eye, iire at agreat Disidvantage, as to Estimating Distances, from \vhnt they could -dowhile they had the trfe of both.

But now when the Distance grows so jjreat, as that,the Position of -theseVisual Axes become Parallel, or so near to Parallel as not to be distin-guifhable from -it: 'This Advaittage is löst, and we can theneeforth onlyconclude, that it is far off,; but not how far. ; H?pce it,is that our view canmake no -Distinction of the Moon’s Distance, from that c of the other iPlanets,or even of the Fixed ‘Stars: But thqy,scem to ps as equasty remote frontus ; though we otherwise know their Distances from us to be ,vastly diffe-rent. Because the'Parallax (as I.may so cäll it) front the different -Position>ot the two Eyes, <is -quite lost, and yndisoernable in Distances.mpchieß tlianthe least of thefc.

So that, though as-tolpiall Distances, we mqy pake sonje Estimaxe; frontthe known Magnitude of the'Object ; And as to Middljng Distances, fromthe Parallax (as I may öall it) arising from the Interval of . the twp Eyes :Yet-even this satter'will hardly reach beyoqd, »if so sor . as the visihso JÖori-Tzon ; and all beyond k.is löst. And therctore there bctng not hing fest toudist the fancy-in Estimating so.great a Distance, but on|y the intermediamObjects: Where thefe Intermediäres appear to the Eye, (as when the Sun orMoon are near the Horizon) the Distance is fansied greater, than where they

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