For if A be the Center of the Earth,
221[Figure 221]
and A N B C D the Spiral Line, having
drawn the Right Lines A B, A D, and the
like, there is the ſame proportion betwixt
the Curved Line A N B and the Right Line
AB, as is betwixt the Curved Line A N B C,
and the Right Line A C; or betwixt
A N B C D and A D: and ſo of the
reſt.
221[Figure 221]and A N B C D the Spiral Line, having
drawn the Right Lines A B, A D, and the
like, there is the ſame proportion betwixt
the Curved Line A N B and the Right Line
AB, as is betwixt the Curved Line A N B C,
and the Right Line A C; or betwixt
A N B C D and A D: and ſo of the
reſt.
And if one draw the Tangents D E, C F,
and B G, the Angles A D E, A C F, A B G, &c.
ſhall be equal. As for the reſt I will, &c.----
and B G, the Angles A D E, A C F, A B G, &c.
ſhall be equal. As for the reſt I will, &c.----
Reverend Father,
Your very humble Servant
DES-CARTES.
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