Salusbury, Thomas
,
Mathematical collections and translations (Tome I)
,
1667
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ſame, not to ſerve for a neceſſary demonſtration, but to adorn a
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Platonick
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Conceit; to which I will add another particular
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vation of our
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Academick,
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which hath in it ſomething of
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ble. </
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<
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>Let us ſuppoſe amongſt the decrees of the divine
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Architect,
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a purpoſe of creating in the World theſe Globes, which we
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hold continually moving round, and of aſſigning the centre of
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their converſions; and that in it he had placed the Sun immoveable,
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and had afterwards made all the ſaid Globes in the ſame place,
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and with the intended inclinations of moving towards the Centre,
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till they had acquired thoſe degrees of velocity, which at firſt
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med good to the ſame Divine Minde; the which being acquired,
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we laſtly ſuppoſe that they were turned round, each in his Sphere
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retaining the ſaid acquired velocity: it is now demanded, in
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what altitude and diſtance from the Sun the place was where the
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ſaid Orbs were primarily created; and whether it be poſſible that
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they might all be created in the ſame place? </
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>To make this
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ſtigation, we muſt take from the moſt skilfull Aſtronomers the
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magnitude of the Spheres in which the Planets revolve, and
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wiſe the time of their revolutions: from which two cognitions is
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gathered how much (for example)
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Jupiter
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is ſwifter than
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turne
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; and being found (as indeed it is) that
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Jupiter
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moves more
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ſwiftly, it is requiſite, that departing from the ſame altitude,
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piter
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be deſcended more than
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Saturne,
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as we really know it is, its
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Orbe being inferiour to that of
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Saturne.
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But by proceeding
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wards, from the proportions of the two velocities of
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Jupiter
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and
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Saturne,
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and from the diſtance between their Orbs, and from the
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proportion of acceleration of natural motion, one may finde in
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what altitude and diſtance from the centre of their revolutions,
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was the place from whence they firſt departed. </
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<
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>This found out,
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and agreed upon, it is to be ſought, whether
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Mars
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deſcending
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from thence to his Orb, the magnitude of the Orb, and the
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locity of the motion, agree with that which is found by
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tion; and let the like be done of the
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Eartb,
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of
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Venus,
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and of
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Mercury
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; the greatneſs of which Spheres, and the velocity of
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their motions, agree ſo nearly to what computation gives, that it
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is very admirable.</
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The circular
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tion is never
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quired naturally,
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without right
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tion precede it.
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<
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>Circular motion
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perpetually
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form.
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The magnitude of
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the Orbs, and the
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velocity of the
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tion of the Planets,
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anſwer
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ably, as if
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ed from the ſame
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place.
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<
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>SAGR. </
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<
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>I have hearkened to this conceit with extreme delight;
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and, but that I believe the making of theſe calculations truly
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would be a long and painfull task, and perhaps too hard for me
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to comprehend, I would make a trial of them.</
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<
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>SALV. </
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>The operation indeed is long and difficult; nor could
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I be certain to finde it ſo readily; therefore we ſhall refer it to
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other time, and for the preſent we will return to our firſt
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ſal, going on there where we made digreſſion; which, if I well
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remember, was about the proving the motion by a right line of no </
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