XCviii COMPARISON-STARS. 



The declinations of the comparison stars, used for the Washington micrometer observations as 

 well as those of many other stars not easily identified in the standard catalogues, or whose 

 positions appeared for any reason not altogether trustworthy have been redeterrnined at the 

 United States Naval Observatory, at Washington, with the mural circle; chiefly through the 

 zeal and courtesy of Prof. Yarnall, whose careful assiduity has materially aided the present 

 investigations, and on some nights by Prof. Major. At the earnest instance of the writer, 

 application was made to the superintendent of the Naval Observatory, by Lieut. Gilliss, for 

 observation of still other declinations. The season of the year naturally prevented the re- 

 determination of all that could be desired, but many important additional positions have been 

 thus provided by Prof. Yarnall, to whom the charge of the mural circle is assigned. The 

 observations, as communicated by Lieutenants Maury and Brasher, are given in their appropriate 

 place. 



Application was also made to my respected friend Prof. Briinnow, of the observatory of 

 the University of Michigan, at Ann Arbor, whose recently acquired and magnificent meridian 

 circle had just been mounted. But the arrangements of the observatory not being completed, 

 and the instrument not yet fully brought into working condition, Prof. Briinnow was able to 

 make but few of the desired observations, and these were not received in sufficient season to be 

 incorporated into the results. They are, however, given with the other determinations for the 

 sake of comparison and reference. 



The materials collected for the compilation of a definite catalogue of star-places, to be adopted 

 as final in the present discussion, are here presented in detail. 



In the first place, the observations of Lieut. Gilliss himself, at Santiago, provide a rich mine 

 of positions of fixed stars, among which are many of those employed for comparison, and all of 

 those used during the second opposition of Mars. During the first .Mars-series the instrument 

 was dismantled, as explained by Lieut. Gilliss in his narrative, and during the two series of 

 Vemts observations it was impossible to observe the comparison-stars upon the meridian in the 

 full glare of day. The following tables present the several observations, their reduction to the 

 mean equinox at the beginning of those years in which they were respectively used for com- 

 parison with the planets, and finally a list of mean positions at these epochs for the comparison- 

 stars, as given by the Santiago meridian-circle. The reference-figures in the last column 

 indicate the number of the star in the special list, or in the General Catalogue of comparison- 

 stars, as the case may be. 



