OBSERVATIONS WITH THE ZENITH TELESCOPE. 



287 



99. Donsink. 1900. Mean Places of 1101 Stars deduced from Observations made with the Meridian Circle at 

 Dunslnk. Dublin, 1899. p same as Paris, '75. 



100. Kustneii (a). 1900. Veroffentlichung der Koniglichen Sternwarte zu Bonn, No. 4. 



Yearly Series. 



101. 1835-1869. EDINBUBGH. Astronomical Observations at the Royal Observatory, Edinburgh. 

 103. 1836-1869. Cambridge. Astronomical Observations made at the Observatory of Cambridge. 



103. 1802-1876. Radcliffe. Results of Astronomical Observations made at the Radcliffe Observatory. 



104. 1863-1887. Madkas. Meridian Circle Observations. 



105. 1879-1883 (a). Brussels. Annales do l'Observatoiro Royal do Brusselles, Nouvelle Series, s same as 



Nautical Almanac ; p same as 57. 



106. 1887-1896. Greenwich. Annual volumes. 



Method of Reduction. 



Approximate positions for 1875 were obtained from whatever source was available. 

 Many of these were the result of a previous reduction, and with very few exceptions the 

 assumed places differed from the final values only by fractions of a second. The 

 assumed proper motions were in part the result of a previous reduction, others were 

 taken from Auwers' Bradley and other sources. 



These assumed coordinates were then reduced to the epoch of the various catalogues 

 in which the star was found, using for this purpose the formula 



I" da 



Ldt 



■]<• 



1875) -I 



, I dru 



3 L (U 



-1 



(r — 1875) 2 + I 



npa 1 



L (it' J 



(t — 1875 ) ; ' 



a being the Right Ascension or Declination of any star. 

 t the epoch of the catalogue. 



The formuke for the differential coefficients for the epoch 1875, using the constants 

 of Struve and Peters, are as follows, in which 

 a = the Eight Ascension. 

 h = the Declination. 



fi = the Proper Motion in Eight Ascension. 

 (i' = the Proper Motion in Declination. 

 % — 8.W225 + [0.126115] sin a tan h + (i. 

 % = [1.302200] cos a + p'. 



- [5.988] fi cos a tan o + [4.812] /»' sin a sec 2 o + [4.99] p p' tau o. 

 [4.68880J (■£-")+ [5-98778] (-§ + ") cos a tan 5 + [4.81169] (| +/" )«naW.« 

 + [4.9866] ft fi' tan o + 0/000 032 210. 

 5 = [4.63380J (I---/") 4- [7.1C387J (£ + ") sin a + [0.73G7J ^ sin 2S. 



<u 



dlr 



(it* 



£= [2.0987] (** I -f) sin a + [7.1689J U 



The numbers enclosed in brackets are logarithms 



da 



^; sin a + [3.0255,;] { (U I 



da 



cos a. 



