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

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    <archimedes>
      <text>
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          <chap>
            <p type="main">
              <s>
                <pb xlink:href="040/01/336.jpg" pagenum="316"/>
              circle, either bigger or leſſer, according as it is more or leſſe
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              mote from the ſaid Poles, let us take the point F, equally diſtant
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              from them, and draw the diameter F O G, which ſhall be
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              dicular to the Axis E I, and ſhall be the diameter of the grand
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              circle deſcribed about the Poles E I. </s>
              <s>Suppoſing not that the
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              Earth, and we with her be in ſuch a place of the Ecliptick, that
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              the Hemiſphere of the Sun to us apparent is determin'd or
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              ed by the circle A B C D, which paſſing (as it alwayes doth) by
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              the Poles A C, paſſeth alſo by E I. </s>
              <s>It is manifeſt, that the grand
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              circle, whoſe diameter is FG, ſhall be erect to the circle A B C D,
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              to which the ray that from our eye falleth upon the centre O, is
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              perpendicular; ſo that the ſaid ray falleth upon the plane of
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              the circle, whoſe diameter is F G, and therefore its circumference
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              will appear to us a right line, and the ſelf ſame with F G,
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              upon if there ſhould be in the point F, a ſpot, it comming
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              wards to be carried about by the Solar converſion, would, upon
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              the ſurface of the Sun, trace out the circumference of that
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              cle, which ſeems to us a right line. </s>
              <s>Its courſe or paſſage will
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              therefore ſeem ſtraight. </s>
              <s>And ſtraight alſo will the motion of the
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              other ſpots appear, which in the ſaid revolution ſhall deſcribe
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              ſer circles, as being all parallel to the greater, and to our eye
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              placed at an immenſe diſtance from them. </s>
              <s>Now, if you do but
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              conſider, how that after the Earth ſhall in ſix moneths have run
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              thorow half the grand Orb, and ſhall be ſituate oppoſite to that
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              Hemiſphere of the Sun, which is now occult unto us, ſo as that
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              the boundary of the part that then ſhall be ſeen, may be the ſelf
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              ſame A B C D, which alſo ſhall paſſe by the Poles E I; you
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              ſhall underſtand that the ſame will evene in the courſes of the
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              ſpots, as before, to wit, that all will appear to be made by right
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              lines. </s>
              <s>But becauſe that that accident takes not place, ſave
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              ly when the terminator or boundary paſſeth by the Poles E I,
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              and the ſaid terminator from moment to moment, by meanes of
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              the Earths annual motion, continually altereth, therefore its
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              ſage by the fixed Poles E I, ſhall be momentary, and
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              ly momentary ſhall be the time, in which the motions of thoſe
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              ſpots ſhall appear ſtraight. </s>
              <s>From what hath been hitherto ſpoken
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              one may comprehend alſo how that the apparition and beginning
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              of the motion of the ſpots from the part F, proceeding towards
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              G, their paſſages or courſes are from the left hand, aſcending
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              wards the right; but the Earth being placed in the part
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              trically oppoſite the appearance of the ſpots about G, ſhall ſtill
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              be to the left hand of the beholder, but the paſſage ſhall be
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              cending towards the right hand F. </s>
              <s>Let us now deſcribe the Earth
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              te be ſituate one fourth part farther diſtant from its preſent ſtate,
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              and let us draw, as in the other figure, the terminator A B C D, </s>
            </p>
          </chap>
        </body>
      </text>
    </archimedes>
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