ON FLAAISTEED'S STARS "OBSERVED, BUT NOT EXISTING." 79 



+2'", or tbat instead of 48'" should be read 50™, and that it is an observation of 29 Sextantu, iden- 

 tical with Pi. W'.Sa (in Tiazzi's catalogue erroneously called 28 Sextanfis). 



Piazzi 10''.S6 for 1800 ]54o 49' 43"; — 1° 43' 10" 



Reduction to 1690 — 1 23 58 +33 G 



Piazzi 8G for 1G90 153° 25' 45"; —1° 10' 4" 



British Catalogue 1486 152 52 15; —1 10 25 



Difference +33' 30"; +21" 



29 Sextantis, or B. Fl. 1491, is 153° 23 45; -1° 10' 30 



which differs from B. Fl. 148G with the correction of +2™, only 1' 30" in right ascension and 5" in 

 declination. 



14) B. Fl. 1647 (7'"). 



Argelander (A. N. No. 227, page 171) says :— "ist eine bis jetzt noch nicht bekannte Beobachtung 

 des Uranus. Aus einer geuaueu Reduction folgt die Position 1714, Dec. 14., 17*' 54™ 57' M. Z. 

 Gr. 11'' 29'" 1''.94; + 4° 11' C".5, selir schou niit den iibrigen Flanisteed'schen Beobachtungen 

 dieses Planeteu iibereinstimmend." 



Baily, on the contrary, in the note to this star, remarks: "I cannot find any star that will 

 correspond with this observation. ]\Ir. Argelander thinks that it may be Uranus, whose position 

 on that day, at 17" 54-" -57' mean time at Greenwich, was 11" 29"' I'.Ol (=172o 15' 29") and 

 D= +4° 11' 6". 5; but the great difference in the declination is against this supposition." 



For the time of observation concluded by Argelander 1 have computed from the solar tables 

 of Hansen and Olufsen : 



The sun's apparent trop. longitude © =262° 59' 23".9 

 The sun's apparent trop. latitude o'=+0''.27 

 The sun's radius vector log. R = 9.9928995 



Also the obliquity of the ecliptic f = 23° 28' 29".2 

 And the nutation in longitude — + 14".5G. 



For the same instant, but diminished by 2" 11'" 34% the time required by the light to travel 

 from Uranus (for which the distance was taken from a preliminary computation), 1 derived from 

 Newcomb's Tables : 



The longitude of Uranus in reference to the mean equinox 168° 9' 22".67 



to which added the nutation in longitude found from the solar tables + 14.56 



gives the true or apparent lotigitude of Uranus X = IGS 9 37.23 



Further the latitude of Uranus /? = + 46' 6".44 



and the radius vector of Uranus log. r = 1.2620674, 



With these data we obtain: 



The apparent right ascension of Uranus a = 172° 15' 47".5 

 The apparent declination of Uranns (J = + 4 11 5 .9 



Distance from the earth log. z/ = 1.2G07247, 

 and the small correction for parallax, to be added to computed declination, will be = — 0".36. 



Hence the final comparison stands thus: 



Tabular computed place 11" 29-" 3M7; + 4° 11' 5".5 



Observed (Argelander's reduction) 11 29 1 .94; +4 11 6 .5 



Difference (C-O) ' +r.23 ^-HO 



Argelander's assertion of this being an observalion of Uranus ("very finely agreeing with 

 the other observations of this planet by Flamsteed") is therefore completely vindicated. Perhaps 

 misled by Baily, no notice has been taken of this observation in the recent tables of Ui'anus. 



