240 DE FICrRA TERRAE 



Ponatur ergo tang. ^^^ =i f , tang. ^^=^ ~ 2; , atque erit 



I H- 2I9 : 1 —i^9~ ^- •s, vnde eruitur z~t: — — -^— ? , quae 



operatio vt folis LogariLhmis abfolui queat, ponatur in 

 Figura 8. femicirculo BDGA radius CBni, et anguli BCD 

 cofinus rz:CE~5B5,5BCD vero tangens — , erit itaque 

 BErr:i-i5„ AE-i-hi,. Porro ob BD:DA=iBD:^BA 

 =DH:HC, et BE:AEzzBD^DA%erit BE:AE- DH-HC^ 



I- ^- 



Ea autem DH:HC=id:i, ergo — f^rr^', con- 



fequenter z~&'t^ et log. srr 2 log. 0-hlog.?, ex quo 

 oritur fequens regula: i. Logarithmus Cofinus Latitudi- 

 nis datae minuatur Logarithmo numeri 289, eritque re- 

 fiduum Logarithmus Cofinus anguU BCD. 2. Duplo 

 Logarithmo Tangentis iBCD addatur Logarithmust.ang. 

 ~^j atque a fumma fubtrahatur duplum Logarithmi 

 finus totius , remanebit Logarithmiis tang. —7^ . 3 . Ab 

 inuenta femifumma ^7^ fubtrahatur inuenta femidifte- 

 rentia ^^7^, et remanebit angulus minor K. Ex hoc 

 fundamento computaui fequentem Laterculum : 



Latl- 



