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

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              <s>
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              on upon the Earths motion; for from the Earth in A it ſhall be
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              ſeen according to the ray A E, with the elevation of the angle
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              E A C; but from the Earth placed in B, it ſhall be ſeen
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              cording to the ray B E, with the elevation of the angle E B C,
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              bigger than the other E A C, that being extern, and this
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              tern and oppoſite in the triangle E A B, the diſtance therefore
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              of the ſtar E from the Ecliptick, ſhall appear changed; and
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              likewiſe its altitude in the Meridian ſhall become greater in the
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              poſition B, than in the place A, according as the angle E B C
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              exceeds the angle E A C, which exceſſe is the quantity of the
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              angle A E B: For in the triangle E A B, the ſide A B being
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              continued to C, the exteriour angle E B C (as being equal to
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              the two interiour and oppoſite E and A) exceedeth the ſaid
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              gle A, by the quantity of the angle
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              E.
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              And if we ſhould take
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              another ſtar in the ſame Meridian, more remote from the
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              ptick, as for inſtance the ſtar H, the diverſity in it ſhall be
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              greater by being obſerved from the two ſtations A and B,
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              ding as the angle A H B is greater than the other
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              E
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              ; which
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              gle ſhall encreaſe continually according as the obſerved ſtar ſhall
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              be farther and farther from the Ecliptick, till that at laſt the
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              greateſt mutation will appear in that ſtar that ſhould be placed in
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              the very Pole of the Ecliptick. </s>
              <s>As for a full underſtanding
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              of we thus demonſtrate. </s>
              <s>Suppoſe the diameter of the Grand
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              Orb to be A B, whoſe centre [
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              in the ſame Figure
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              ] is G, and
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              let it be ſuppoſed to be continued out as far as the Starry Sphere
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              in the points D and C, and from the centre G let there be erected
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              the Axis of the Ecliptick G F, prolonged till it arrive at the ſaid
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              Sphere, in which a Meridian D F C is ſuppoſed to be deſcribed,
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              that ſhall be perpendicular to the Plane of the Ecliptick; and
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              in the arch F C any points H and
                <emph type="italics"/>
              E,
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              are imagined to be taken,
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              as places of fixed ſtars: Let the lines F A, F B, A H, H G,
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              H B, A
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              E,
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              G
                <emph type="italics"/>
              E,
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              B
                <emph type="italics"/>
              E,
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              be conjoyned. </s>
              <s>And let the angle of
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              ference, or, if you will, the Parallax of the ſtar placed in the
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              Pole F, be A F B, and let that of the ſtar placed in H, be the
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              angle A H
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              B,
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              and let that of the ſtar in
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              E,
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              be the angle
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              A
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              E
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              B. </s>
              <s>I ſay, that the angle of difference of the Polar ſtar F, is
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              the greateſt, and that of the reſt, thoſe that are nearer to the
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              greateſt are bigger than the more remote; that is to ſay, that the
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              angle F is bigger than the angle H, and this bigger than the angle
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                <emph type="italics"/>
              E.
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              Now about the triangle F A B, let us ſuppoſe a circle to be
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              ſcribed. </s>
              <s>And becauſe the angle F is acute, (by reaſon that its baſe
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              AB is leſſe than the diameter DC, of the ſemicircle D F C) it ſhall
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              be placed in the greater portion of the circumſcribed circle cut
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              by the baſe A B. </s>
              <s>And becauſe the ſaid A B is divided in the
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              midſt, and at right angles by F G, the centre of the </s>
            </p>
          </chap>
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