CorreB'wn far the Dip deduced from Obfirvat'ton, 15 \ 



Example. 

 The fun's declination 4° 32' 30" and its ferai-diameter 15'58" took the following ob- 

 fervation : 



The meridian diftance of the fun's neareft limb from South. North, 



the horizon of the fea —— 78° 36' 30" = iol° i'2o" 



Refra£lion per table -^— — — — o 1 1 = + o i r 



Diftances corf, for refraction — — —— =78 36 19 = loi i 31 



Error of the fextant — . ■ + i 32 +132 



Sun's femi-diameter — — .^— + '5 58 + 15 58 



Half difference or the dip found ■ — 



Altitude reduced 

 Zenith diftance 



Diff. 12 50 

 The fun's declination N. -____ ■ =43230 Half =625 



Latitude of the ftiip N. ■■ =15 45 06 



— D 



ip. 



I regret that I cannot in this paper infert the dip which I have found in my obferva- 

 tions ; foj- 1 only retained the latitude of the fhip determined thereby as is ufual at fea. I 

 generally reje£t:ed the error of the inftrument, the dip, and femi-diameter, as they affe£l: 

 both obfervations with the fame fignsj and reduced the obfervation by the following, 

 method : 



South. North. 



Sun's diftance as before ^— 78° 36' 30" 101° i'2o" 



Refraflion — — — - — on + oir 



Dif. corr. for refraftion ' 78 36 19 itoi 1 31 101° i'3i" 



+ 78 36 19 



Sum 



Sum of femi-diameter, dip, and refrac- 

 tion = half difference +11 5 180 



179 37 50 



Diff. 22 10 



Half II 5 joi 12 36 

 90 



The zenith diftance as before — — • =11 1236 Zenith dift. =n 1236 



It may be obferved, that neither the dip, femi-diameter, or index error can affeft the 



zenith diftance of the fun's centre ; and the refra£lion being fmall near the zenith, the 



rcfult muft be true, if the angles are accurately taken j and it is only neceffary to obferve, 



that when the fum of the diftanccs is lefs than 1 80, the half difference muft be added to 



5 the 



