cxl 



COMPARISON-STARS. 



Lastly, there is another class of stars to be examined ; namely, those observed in connection 

 with Mars upon the meridian at different places, and although not near enough to the planet 

 to be treated as comparison stars, yet forming in fact the basis upon which the respective series 

 of meridian observations must rest. The places of these stars have been reduced from the 

 several authorities, together with those which were required for our General Catalogue, and the 

 stars are referred to in the preceding special tables by index-letters instead of numbers. 



The data employed for the determination of their adopted places are given below, and followed 

 by the resultant list; the method of reduction and form of presentation being the same with 

 that for the 148 stars of the catalogue proper. 



To this class belong also /9 Tauri and /9 Geminorum, which being fundamental stars have 

 been so thoroughly and frequently observed at Greenwich during the period of the Mars 

 observations, that the places taken direct from the Greenwich Catalogue for 1850 seem more 

 trustworthy than those derived from any combination of observations made at different epochs. 



Places of Stars not used for comparison., but observed iviththe Gape Mural Circle, in connection witli 



Mars I. 



These determinations are given by Mr. Maclear in the Memoirs of the Royal Astronomical 

 Society of London, volume XX, pp. 104, 5. They have been used with the regular micrometric 

 comparison-stars, determined during the same period at the Cape, for obtaining the constant 

 quantity which is to be subtracted from all the circle-measurements, both of planets and stars, 

 at the Cape, in order to reduce the declinations to our adopted standard. 



