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

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              ment that they generate and diſſolve; for if without generating
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              or corrrupting, they ſhould appear there by onely local motion,
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              they would all be ſeen to enter, and paſs out by the extreme
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                <arrow.to.target n="marg116"/>
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              cumference. </s>
              <s>The other obſervation to ſuch as are not ſituate in
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              the loweſt degree of ignorance in Perſpective, by the mutation
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              of the appearing figures, and by the apparent mutations of the
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              velocity of motion is neceſſarily concluding, that the ſpots are
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              contiguous to the body of the Sun, and that touching its
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              cies, they move either with it or upon it, and that they in no wiſe
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              move in circles remote from the ſame. </s>
              <s>The motion proves
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                <arrow.to.target n="marg117"/>
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              it, which towards the circumference of the Solar Circle,
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              appeareth very ſlow, and towards the midſt, more ſwift; the
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              gures of the ſpots confirmeth it, which towards the circumference
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                <arrow.to.target n="marg118"/>
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              appear exceeding narrow in compariſon of that which they ſeem
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              to be in the parts nearer the middle; and this becauſe in the
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              midſt they are ſeen in their full luſter, and as they truly be; and
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              towards the circumference by reaſon of the convexity of the
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              bous ſuperficies, they ſeem more compreſſ'd: And both theſe
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              diminutions of figure and motion, to ſuch as know how to obſerve
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              and calculate them exactly, preciſely anſwer to that which ſhould
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              appear, the ſpots being contiguous to the Sun, and differ
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              cileably from a motion in circles remote, though but for ſmal
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              intervalls from the body of the Sun; as hath been diffuſely
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                <arrow.to.target n="marg119"/>
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              monſtrated by our ^{*} Friend, in his Letters about the Solar ſpots,
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              to
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              Marcus Velſerus.
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              It may be gathered from the ſame
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              tion of figure, that none of them are ſtars, or other bodies of
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              ſpherical figure; for that amongſt all figures the ſphere never
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              appeareth compreſſed, nor can ever be repreſented but onely
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              fectly round; and thus in caſe any particular ſpot were a round
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              body, as all the ſtars are held to be, the ſaid roundneſs would as
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              well appear in the midſt of the Solar ring, as when the ſpot is near
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              the extreme: whereas, its ſo great compreſſion, and ſhewing its
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              ſelf ſo ſmall towards the extreme, and contrariwiſe, ſpatious and
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              large towards the middle, aſſureth us, that theſe ſpots are flat
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                <arrow.to.target n="marg120"/>
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              plates of ſmall thickneſs or depth, in compariſon of their length
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              and breadth. </s>
              <s>Laſtly, whereas you ſay that the ſpots after their
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              determinate periods are obſerved to return to their former aſpect,
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              believe it not,
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              Simplicius,
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              for he that told you ſo, will deceive
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              you; and that I ſpeak the truth, you may obſerve them to be hid
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              in the face of the Sun far from the circumference; nor hath your
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              Obſervator told you a word of that compreſſion, which
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              rily argueth them to be contiguous to the Sun. </s>
              <s>That which he
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              tells you of the return of the ſaid ſpots, is nothing elſe but what
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              is read in the forementioned Letters, namely, that ſome of them
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              may ſometimes ſo happen that are of ſo long a duration, that </s>
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