iON THE MERIDIAN. 



0> fi) 

 So that if X — X be exprefled by diWt 



/ - 



(2) (0 



X = X + d, ' 



C (s) or 



(3) fl) \SiPu*^ f — Sin.*- ? 



X =r X -f d< --r' 



C CO (!)■ 



(4) (3) \Sin.^ i — . Sin.* i 



X S3 X 4- il<- ^ _— -V&ci 



/ («> ^ (0( 



C^Sin.* J — Sin.* i 



^. q. ^, 4«^- X — X 4- (/<— ».—— 



J ■■ (2) (1] 



f^Siu.J / — Sin.» I 



where « denotes the number of degrees, and #£he increment feo the 

 1 ft degree. Here it is evident that d is the only unknown quantity to 



(') (5) (S) («) 



be determined, since X 4- X -f X . ; , X =s .»4 the terreftrial mea- 



(1).-. 

 5ure of an are oin complete degrees, X being the meafure of the firGl '■ 



(1) ^■ 

 degree in latitude / by obfervation. 



(3)""' •(!)' ' («) ^ 0) 



(1) (Sin.si — Sip.2 O I ; I (SiD.2 / — Sin.^Ov 



Heiiceii=s»X4"^ (<? + 1 ^5- 1— — _ — . . - — j 



(2> (1) 



(Sin.* I -. Sin;» > 



(n (!> > 



(^ -i. n X) . (Sin.s /! — Sin.!' 



Arid d .= — . — __ — . ---- 



O) J O ' (3) (I) («) (1) 



fSin.' ^ — Siu.M) 4. (S;n.« i — SiQ.M) &c. o ; . 4- (Sia.2 f — Siu.= i 



whence d becomes a known quantity ; and fince (Siu* i — Sin.* /) 



i '^ 



B a Gonftant and known quantity, if——: — be denoted by ^, 



^ (^) „ (0 



