PHYSICAL AND LITERARY. 123 



PROP. VI. Probl. IV. Fig. 6. 



Let AP be the greater axis of a pla- 

 net's- orbit, S the focus the place- 

 of the fun, A the aphelion, P the"^ 

 perihelion ; upon AP let the femi- 

 eirck ABP be defcribed •, let C be 

 the center, and let the angle ACB 

 be the mean anomaly of the planet 

 at any given time : it is required 

 ''to find the anomaly of the excen-. 

 trie. 



Join SB, and draw CD parallel to SB 



meeting the circle in D : join SD in BD : 



take the arc DG, fo that the fine of the angle 



BCD may be to the tangent of the angle 



CDS, as the excefs of the arc BD above its 



fine to the arc DG ; and join CG : the 



angle ACG will be nearly the anomaly of the 



excentric. ■ 



Join SG ; draw BE perpendicular to CD 



.meeting CD in E, and draw CF parallel to 



SD meeting DF a tangent to the circle at D 



1| inF. 



Because 



