round about: Now, fince these two Points in the Heavens, which are oppofite to the Ends of the Axis of the Sphere, are quiefcent, and all the other Parts of the Heavens have an apparent Motion about them, therefore they were looked upon as the two great Cardinal Points, or Hinges, on which the whole Fabric of the World did turn.

Euphrof. I think the Defcription of thefe Poles in Virgil is very fine, when he says,

Two Poles turn round the Globe, one seen to rife O'er Scythian Hills, and one in Lybian Skies; The firft fublime in Heav'n, the laft is whirl'd Below the Regions of the nether World; Around our Poles the fpiry Dragon glides, And, like a wand'ring Stream, the Bears divides, The less and greater, who by Fate's Decrees, Abhors to dive beneath the Southern Seas; There, as they fay, perpetual Night is found, In Silence brooding on th' unhappy Ground: Or when Aurora leaves our northern Sphere, She lights the downwards Heav'ns, and rifes there; And when on us fhe breathes the living Light, Red Vefper kindles there the Tapers of the Night. Dryden's Virgil. But does he not here ascribe a Motion to the Poles them felves?

Cleon. He does; and by it only means, that when we go North or South, they appear to afcend or defcend, above or below the Horizon; at least, this is all the Motion the Poles can poffibly have. But more of this when we come to the Ufe of the Globes.

Thus have we passed through so much of the Doctrine of the Sphere, as is neceffary to enable you to have a right Understanding of the Globes and Orrery, which will exemplify and illuftrate all thofe Matters, and make them familiar and eafy to your Apprehenfion.

Euphrof. Dear Cleanicus, you highly oblige and delight me; I think long e'er thofe Inftruments come in Play: Pray, which are we to have next, the Globes, or Orrery?

Cleon. The Orrery, my Euphrofyne; I have provided one for that Purpofe, which will afford you a pleasurable Entertainment for the next Leifure-Hours.

YE

DIALOGUE VII.

Of the ORRERY.

Cleonicus.

ES, my Euphrofyne; this is the fam'd Machine, of which I promised you the Sight and Ufe, when we laft conversed on these Subjects.

Euphrof. A fhowy Piece of Art it seems to be, indeed! Pray, who was the first Inventor of it?

Cleon. This Machine was invented by Degrees, and made in its utmoft Perfection, firft by Mr. Rowley, for King George the Firft; after which the Earl of Orrery bespoke another; and from him, it is fuppofed by some, that it had its Name: But fome will have it derived from a Greek Word of the fame Sound, which fignifies to fee; because in this Machine we fee all the Motions of the heavenly Bodies performed in the fame Manner as they are in Nature itself.

Euphrof. Are there not different Sorts of Inftruments of this Kind made; because, I think, I have feen the Print of an Orrery, of a different Make from this?

Cleon. Yes; fince the first Invention they have been variously made, and very much improved by feveral Artifts; but the Orrery conftructed by the late ingenious Mr. Dean exceeds in Point of Neatnefs and Elegance all that has been yet made, if you except the Motions of the Satellites of Jupiter and Saturn; but there feems a great Deal wanting yet, to render an Orrery more fimple in its Structure, and of an eafier Purchafe than those which have been hitherto made; for the first were fold for a thoufand Guineas; none of the largest Sort for less than three hundred.

Euphrof. Had the ancient Aftronomers no Contrivance of this Kind, to represent the Motions of the heavenly Bodies?

Cleon. Yes, it appears they had fomething analogous to it, made by that famous Mathematician, Archimedes, on whom the Latin Poet Claudian wrote a merry Epigram, in the English Tranflation of which you will fee Row

ley's

ley's Name, inftead of Archimedes, as given us by Dr. Harris in his aftronomical Dialogue, Page 182.

When lately Jove the Orrery furvey'd,

He, fmiling, thus to Gods in Council faid;
How fhall we fint prefuming Mortals Pow'r?
The Syracufan Sage did, once before,

The heav'nly Motions fhew in Spheres of Glass,
And the erratic Orbs and Stars express:

But his Machine, by one fix'd Pow'r and Weight,
Mov'd, and was govern'd, as we are, by Fate;
While the bold Rowley, in his Orrery,
Keeps his firft Pow'r, just like his Genius free:
He knows the fecret Spring, and can impart
Laws to the Whole, and to each fingle Part.
His daring Hand, or brings, or hinders Fate:
He makes the Earth thro' filver Zodiacs run,
Juftly obfequious to the golden Sun:

While the bright Moon, fhining with borrow'd Light,
Marks out the Months, and rules the fable Night:
And all obedient to his fole Command,

Turn round their Axis, as he turns his Hand;
Their Phafes, and their Afpects all difplay,
And at his Beck exhibit Night or Day.
He makes Eclipfes, as he will, appear,
For any past, prefent, or future Year;

Shews their true Course, and roots out vulgar Fear.
Guiltless Salmoneus at your Suit I flew,
Shall I, to please you, take off Rowley too?
Oh! no, all cry'd, the glorious Artift fpare,
Tranfplant him hither, and make him a Star.

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Euphrof. This is an ingenious Piece of Wit, indeed but the Inftrument highly deferves it, to all Appearance; it being in the external Frame, and (I doubt not) in the internal Structure, an admirably beautiful and exquifite Piece of Workmanship.

Cleon. All you obferve is very right; and Pity it is, that the Coftlinefs and Magnificence of fo curious and ufeful an Inftrument fhould be a Bar to its common Ufe. I fhall now proceed to give you a View of each particular Part, in a general Defcription of the Whole.

The Frame, which contains the Wheel-work, &c. and regulates the whole Machine, is made of fine Ebony, and