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.