26 



ASTRONOMICAL OBSERVATIONS 



Reduction to centre 



/t'= .... 



k'-\-h'= 



k'—b'= 



d'= 



m — n^ 



Reduction to time of true 6 



— n"5 



873.4 



+ 1445.0 



+ 301.8 



+ 17° 19' 12".l 



+ 90.65 



118^09 



+8 04.2 



14 20 48.8 



14'' 23>" 53^0 

 4,'=40o-52'.7 



Time of true 6 in Van Rensselaer mean time 



Reduction to centre 

 k'= .... 

 k' + b' = 

 l'—h'= 



a' +2^—^= ■ 



m — ?i= 



Reduction to time of true 6 



t .... 



+ 11".5 



902.0 



+ 1765.5 



+ 38.5 



+ 17°21'37".0 



—911.66 



118M4 



—30-' 52^0 



14 54 18.3 



14'' 23-" 26^3 



.^'=106° 48'.0 



14'' 23'" 53^0 + 1.84 dB from immersion. 



14 23 26.3 —%MdB from emersion. 



dB = — 3".0 Hence longitude of Van Rensselaer Harbor from immersion 4'' 43"" 5P.8 



from emersion 4 43 51.8 



Longitude from the Observations of the Occultation of Saturn's Ring. 



.lanuary 8, 1854. 

 Immersion, last contact of ring 12'' 42- 

 Emersion, " "13 39 



25^7 I Sidereal time or 22'' ll™ 28«.7 ) Appro.x. Grecu- 



115 j at Van Rensselaer 23 08 05.2 ) wich mean time. 



From the Greenwich Nautical Almanac, as corrected by the Greenwich observations : — 



At immersion, a C . . .3'' 32"° 49^.40 

 At emersion . . . . 3 34 40.95 



(CoiTcction to Nautical Almanac — 0^.36.) 

 At immersion, 6 C . . . +17° 47' 21".3 

 At emersion . . . . 17 56 22.2 



(Correction to Nautical Almanac — 10".0.) 

 At immersion, horizontal parallax <L 54' 14".9 

 At emersion . . . . .54 14.3 



(Correction — 0".l according to Adams.) 

 At immersion, semidiameter C . . 14' 47". 6 

 At emersion . . . . .14 47.4 



(Correction — l".l according to Oudeman.) 



Immersion. 



(L 's horizontal paral. at Van Rensselaer 54' 04".5 

 Relative parallax « = . . 54 03.5 



a— s= .... —137° 24 04.5 



a'_a=p= . . . _ 7 36.83 



«'—«=?= ... — 52 59.54 



Augmented semidiameter <L . 889.7 



At immersion, o h . . .3'' 33"" 10\75 

 At emersion . . . . 3 33 16.45 



(Correction to Nautical Almanac +0^.18.) 

 At immersion, 5 h . . . +17° 00' 34".3 

 At emersion . . . . 17 00 33.9 



(Correction to Nautical Almanac — 9".0.) 



Horizontal paralla.x h 

 Semidiameter h 



Mean time of 6 , Greenwich 



I".0 

 8".9 + l".0 



22'' 25"' 18'. 9 



Emersion. 



C 's horizontal paral. at Van Rensselaer 54' 03".9 



Relative parallax « = . . 54 02.9 



o— s= .... —151° 07 39 



a'—a.=l}= . . . — .5 25.96 



S'- «=</= ... — 53 24.21 



Augmented semidiameter C . 889. 2 



For the construction of the diagram the following quantities were used : — 

 Apparent a C at immersion . . . .3'' 32"' 18''94 

 Relative apparent difference in AR (reduced) . ^13' 49".4 

 " " " in deciinatiun . — 6 12.5 



At emersion 3'' 34"" 19^22 

 + 15' 0O".O 

 + 2 24.2 



Geocentric elements of Saturn's ring: — 

 p = —2° 26' 

 a = 44".3 

 6=— 17.9 



a'= 29."4 



f/=_]2.0 



Southern surface visible. 



