572 Proceedings of the Royal Irish Academy. 



Determining the values of R^^ and Ry by measures of the second 

 comparison star, for which Aa and AS are known, we deduce the 

 values of Aa' and AS' — the differences in K.A., and declination of the 

 comet from the central star — by substituting them in the same 

 formulae. 



"^"e thus find that the differences in R.A. and declination between 

 the comet and BD + 7°, 4886, are, respectively, on the first plate 



+ 22^ -1 and + 10' 20"; 



and on the second plate, which was taken three-quarters of an hour 



later, +19^-4 and + 9' 56". 



"We have next to fijid the position of the comparison star on the 

 night in question. 



This star was observed by Bessel in his Koenigsberg zones, and is 

 ISo. 209 of 22^ in "Weisse's " Positiones Mediae Stellarum Fixarum in 

 Zonis Eegiomontanis." 



Its position for 1825 is there given as 



22b 23- p. 81^ + 6° 53' 51"-7. 



Its mean place for 1894 is therefore 



22h 26" 29= -09. + 7° 14' 47"-7. 



The corrections necessary to reduce to the apparent place for 

 I^ovember 30th are, respectively, + 2=-59 and 18"-8, 

 so that we have as the apparent place on that date 



221^ 26"^ 3P-68, +7° 15' 6"-5. 



Adding the values found above for Aa' and AS', we find the 

 comet's position — 

 on the first plate, 22*^ 26=" 53^-8, + 7° 25' 27", 



on the second plate, 51-1 3. 



The middle of the exposures corresponded respectively to &" 40" 

 and 7"^ 25™, G. M. T., but no great accuracy was attempted in 

 determining these epochs. It will, accordingly, be best to take the 

 mean of the two, and we find the apparent position of the comet 

 corresponding to 7^^ 2'" -5 G.M.T., November 30th, 1894, to be 



22*^ 26" 52= -5, + 7° 25' 15". 

 The corresponding quantities, as found by interpolations fi'om Dr. 

 Eacklund's Ephemeris, published in Nature, November 22, 1894, are 



22^ 26" 53=-75, + 1° 25' 51"-5. 



