Salusbury, Thomas, Mathematical collections and translations (Tome I), 1667

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            <pb xlink:href="040/01/440.jpg" pagenum="418"/>
            <p type="main">
              <s>SALV. </s>
              <s>I will uſe my utmoſt endeavours to render my ſelf
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                <arrow.to.target n="marg813"/>
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              intelligible, but the difficulty of the accident it ſelf, and the
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              great attention of mind requiſite for the comprehending of it,
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              conſtrains me to be obſcure. </s>
              <s>The unequalities of the additions
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              and ſubſtractions, that the diurnal motion maketh to or from
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              the annual dependeth upon the inclination of the Axis of the
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              urnal motion upon the plane of the Grand Orb, or, if you pleaſe,
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              of the Ecliptick; by means of which inclination the Equinoctial
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              interſecteth the ſaid Ecliptick, remaining inclined and oblique
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              upon the ſame according to the ſaid inclination of Axis. </s>
              <s>And the
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              quantity of the additions importeth as much as the whole
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              ter of the ſaid Equinoctial, the Earths centre being at the ſame
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              time in the Solſtitial points; but being out of them it importeth
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              leſſe and leſſe, according as the ſaid centre ſucceſſively
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              cheth to the points of the Equinoxes, where thoſe additions are
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              leſſer than in any other places. </s>
              <s>This is the whole buſineſſe, but
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              wrapt up in the obſcurity that you ſee.</s>
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            <p type="margin">
              <s>
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                <emph type="italics"/>
              The cauſes of
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              the inequality of
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              the additions and
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              ſubſtractions of the
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              diurnal converſion
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              from the annual
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              motion.
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              </s>
            </p>
            <p type="main">
              <s>SAGR. </s>
              <s>Rather in that which I do no not ſee; for hitherto I
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              comprehend nothing at all.</s>
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            <p type="main">
              <s>SALV. </s>
              <s>I have already foretold it. </s>
              <s>Nevertheleſſe we will try
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              whether by drawing a Diagram thereof, we can give ſome
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              ſmall light to the ſame; though indeed it might better be ſet
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              forth by ſolid bodies than by bare Schemes; yet we will help our
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              ſelves with Perſpective and fore-ſhortning. </s>
              <s>Let us draw
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              fore, as before, the circumference of the Grand Orb, [
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              as in
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              Fig.
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              4.] in which the point A is underſtood to be one of the
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              Solſtitials, and the diameter A P the common Section of the
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              Solſtitial Colure, and of the plane of the Grand Orb or
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              tick; and in that ſame point A let us ſuppoſe the centre of the
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              Terreſtrial Globe to be placed, the Axis of which C A B,
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              clined upon the Plane of the Grand Orb, falleth on the plane of
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              the ſaid Colure that paſſeth thorow both the Axis of the
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              ctial, and of the Ecliptick. </s>
              <s>And for to prevent confuſion, let
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              us only draw the Equinoctial circle, marking it with theſe
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              cters D G E F, the common ſection of which, with the plane of
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              the grand Orb, let be the line D E, ſo that half of the ſaid
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              quinoctial D F E will remain inclined below the plane of the
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              Grand Orb, and the other half D G E elevated above. </s>
              <s>Let
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              now the Revolution of the ſaid Equinoctial be made, according
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              to the order of the points D G E F, and the motion of the
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              tre from A towards E. </s>
              <s>And becauſe the centre of the Earth
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              being in A, the Axis C B (which is erect upon the diameter of
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              the Equinoctial D E) falleth, as hath been ſaid, in the
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              tial Colure, the common Section of which and of the
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              Grand Orb, is the diameter P A, the ſaid line P A ſhall </s>
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          </chap>
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