The DoEtrine

but (per Lem. i Liz :;

/j

z — b: AN— —-JhfL and (per F/g.)

zz — bss „ rz — br

z: -^- ::r:T,AXR=

double which (v/Z.) — . T 2 — - , ta-

ken from = TjRXT sound

above, leaves -y- « (per hem. 2 .) 7^

MAt.

QjE.D

COR I

Hence, if the Elevation MAt andhorizontal Amplitude AM are given,the Distance AX on a Plane of any gi-ven Descent MAX , may be found \lor ( by the 13th. and last) 7J RXJ+ T,XRA, m&T,MAt+zT y MA%

(~ 2 f j