ASTKONOMICAL AND GEODETIC OBSERVATIONS. 



GEOGRAPHICAI^ POSITIONS. 



Proven, North Greenland, Station, near the Governor's House. 



Obseryations for time, August 6th (A. M. 1th), 18G0. 



Double altitudes of the sun with Wiii'demann's sextant. 



-82' 5" 

 + 31 35 



Index 



'{■ 



Pocket chronometer 



2© 



8" oe-" W 



51° 18' 00' 



06 54 



23 10 



07 36 



28 20 





2© 



8 08 19 



56 80 20 



08 55 



34 15 



09 21 



SI 05 



Temp. + 48° ¥., pressure 29'^80 

 Let ^ = latitude 



+ 62 F. 



Correction — 15 



n 



Pocket chronometer 



8" 09- 



56= 



10 



27 



11 



17 



8 11 



57 



12 



23 



18 



09 



T„.i„. f-32' 20" ^ 



56< 



2^ 



41' 35" 

 44 20 

 50 20 



2© 

 57 10 

 01 00 

 06 00 



1 + 31 25 



Correction — 2 7 ".5 



7i = altitude 

 h = declination 

 t =liour angle 



then 



cos t =^ 



shi 7i — sin ^ sin 8 

 cos (|) cos 8 



Approximate latitude 72° 23', approximate longitude Z^ 42"" west of Greenwich. 

 The first column of the following table contains the mean chronometer time T, the 

 second the altitude corrected for index error, refraction, parallax (in altitude), and 

 semi-diameter. The refraction was computed for the first and last, and interpolated 

 for the middle times. The third column contains the hour angle computed by the 

 above expression ; converting t into time and applying the equation of time, the 



chronometer correction A I" was found as given in the last column. A ) "'" sign 



indicates chronometer I ^^T" on local time; -j ~ indicates < g^^yi^g ^.^^q^ j?qj. ^j^g 



r,= V 44".7 



first and last set r= — 1' 45". 9 

 + 16° 18' 8" for the middle. 



7ti^ + 7". 5 and 8 = 



T 

 8"^ 6" 53^8 

 8 8 51.7 

 8 10 33.3 



8 12 29.7 



n 

 28° 23' 56" 

 28 30 55 

 28 36 41 

 28 43 05 



—44° 15' 

 —43 44 

 —43 19 

 —42 50 



13" 



43 

 18 



52 



Slean, 



aT 



-HI" 01-" 33= 



86 



86 



34 





-1-1 01 34.7 



* To the reading off the arc I shall give the sign -|-, to that on the arc the sign — , in order to 

 obtain at once the index correction. In the record the observer always notes the index error and 

 the correction has therefore the opposite sign ; in this paper the sign was at once changed. This 

 note applies to the sextant as well as to the reflecting circle. 



