The theoriques of the seuen planets shewing all their diuerse motions, and all other accidents, called passions, thereunto belonging. Now more plainly set forth in our mother tongue by M. Blundeuile, than euer they haue been heretofore in any other tongue whatsoeuer, and that with such pleasant demonstratiue figures, as euery man that hath any skill in arithmeticke, may easily vnderstand the same. ... VVhereunto is added by the said Master Blundeuile, a breefe extract by him made, of Maginus his Theoriques, for the better vnderstanding of the Prutenicall tables, to calculate thereby the diuerse motions of the seuen planets. There is also hereto added, The making, description, and vse, of two most ingenious and necessarie instruments for sea-men ... First inuented by M. Doctor Gilbert ... and now here plainely set downe in our mother tongue by Master Blundeuile.

CHAP. IIII.

Of the eight Heauen.

1. THe eight Heauen is situated vnder the ninth Hea∣uen, and moueth from West to East contrarie to the motion of the first moouable, vpon the poles of the true Eclipticke, making his reuolution in 25816 Aegyp∣tian yeares, and dependeth wholly vpon the meane Equinox.

2. In this sphere are imagined also an Aequinoctiall and an Ecliptick line: and the Ecliptick line of this Heauen is alwaies in the same plane with the Ecliptick of the 9 and 10 Heauens, and swarueth not from the true Ecliptick at all. But the Aequinoctiall points of this sphere do moue from the true Equinoxes, sometimes forward, and some∣times

times backward, euen as the meane Equinox of the ninth sphere moueth.

3. This sphere is apparent to the eye, by reason of the multitude of starres which are therein: the moouing of all which starres, and all other the inferior lights, is ac∣counted or reckoned from the first starre of the Rams horne, as from a visible beginning, although the same be vnstable, by reason of the changeable moouing of the Precession of the meane Vernall Equinox.

4. The Precession of the Equinox is a portion of the true Ecliptick, comprehended betwixt two great circles, whereof the one passeth through the first starre of the Rams horne, and the other through the Equinox; which if it be the true Equinox, then the arch of the Eclipticke, comprehended betwixt the two said circles, is called the true Precession: but if it passe through the meane Equi∣nox, then it is called the meane Precession of the Ver∣nall Equinox.

[illustration]

As for example, suppose in this figure the line K G to be the true Eclipticke, and I F to be the Aequinoctiall of the first moouable, crossing one another in the point A, which representeth the true Equinox, vnto which point when the Sunne commeth, it is Equinox throughout all the world: and suppose M to be the first star of the Rams horn, through which a right perpendicular line passeth, signifying a great circle drawne through the first starre of the Rams horne, & also through the poles of the true Eclipticke: and suppose L H to be another great circle drawne through the true Aequinoctiall point A, and through the poles of the true Eclipticke, so shall M A be the true Precession of the Vernall Equinox. In like manner suppose the line D E to bee another great cir∣cle, passing through the point E, signifying the meane Equinox, and also through the poles of the true Eclip∣ticke, so as the arch of the true Eclipticke, which is com∣prehended betwixt M and E, is the meane Precession of the vernall Equinox. And this meane Precession is readily found by the 14 Cannon, as the 8 Precept tea∣cheth, and the title thereof in the said 14 Cannon, is Praecessionis Aequinoctiorum. But the true Precession is to be found by helpe of the Prosthapheresis, which was defined in the third definition of the third chapter.

And although that there be many other circles both great and little, which the Astronomers vse, as the circles of Positions, Azimuths, and many others, yet will I only speake of such circles, arches, and points in the Heauen as are belonging to our present purpose (because I haue spoken of the others in my sphere) shewing what is the longitude, latitude, and declination of any star or point in this Heauen.

5. The longitude of any starre is an arch of the Eclip∣ticke, comprehended betwixt the true Vernall Equinox, and the circle of latitude of the said starre or point.

6. The circle of latitude is a great circle passing through the poles of the true Eclipticke and the centre of the starre. Of which circle, that part which is betwixt the centre of the starre and the true Eclipticke, is called the latitude of the starre.

7. The circle of declination is a great circle, passi••g through the poles of the world, and through the centre of any starre or other point in the firmament: and that part of this circle which is contained betwixt the said starre and the true Aequinoctiall line, is called the decli∣nation of the starre.