Z S rz: ^ afllgnauimus, facile crit omnibus cafibus Diame- 

 trum apparentem D determinare ope fequentis regulae: 



Primo tenendiim ejl ^ Blametrum apparentem non a ver- 

 tice Obferuatoris V, fed ab eius zenith 2 pendere; 

 tum vero, cognitam effe debere Parallaxin Lunae ho- 

 rizontalem tt vna cum Diamctro horizontali A. Hinc- 

 que^ fi diflantia loci Lunae apparcntis S a zenith Z, 

 fuerit 2. S — ^, erit Diameier apparens hoc loco 

 D — A ( I -1- TT cof. ^) ; vnde patet in ip/o zenitb, 

 *vbi ^ mr o, diametrum apparentem fore D — A ( i + tt ), 

 ficque non in 'vertice Jed in zenith Diameter .Lunae 

 erit maximus. 



DE 



