The Use of the Globes.

299

^ °f the General Meridian or Horizon,

’•hen they are commonly call’d Maps

of

J ‘5: j yP er pendicular to C P and C E. Take the Arch1 e 4 • £ ree > an< ^ 15 raw A i and the Perpendicular td\

Place I. Now put Z'CE, a = CP,a ‘Us nT ^ h y ~ D I; and let 1, t, s, denote the’’AUfti "n^ent, and Secant of the Angle IB D ;fy. "piA let A I ee: r.

L slere fore 17 t -}- 1 = V, and so /’ —r = 1. The or, I.

- th c p ls the Centre of a Circle touching the Ellipsis^it u s° lnts I, i. The Angle I B E = D IF is the

V

A,

H

. fy r ionics

1 : a,

— a. Theor. II.

3 — — a z~ p, the Parameter. Theor, III.i z

41 : r :: p : I E — sy. Theor. IV.

5.1 : t :: y D F = t y. Theor. V.

6 t: 1 :: lF = sy : IB=^. Theor. VI.Oi::ji:DB=-, Theor. VII.

Air fy

Æ^ausi

V 1 fy

w- j 12

Ify re (9)

A,

id

also

t

8;EDXD«:DI‘::CE‘:CP*.

9 zs — xx : yy :: zz : uu :: 1 : a. Theor. VIII.10 CD : CE :: CE : C I, per Conies^x : % :: z : x + ty,zz — V 1 + ty x, or z a —-4 = ty x.

1 : a :: / y x : y z :: t x : y.

y — atx , or x — —. Theor. IX.at

11

V (l +)

\

etef.

<1.

^>1

Qre

« also

also

a x'

1 =DB. Theor. X.

18

y ~ stx, z x =z x* xty~ x z + at'x*.z = x z X i-j-att, ■.•z=x v /T+att. Th. XI.

^ - —r— t a- = —r=L=. Theor. XII.

* 9 y -

* lA-att

y/ i-\-att. Theor. XIII.

Because