ASTRONOMY. 373 



Bringing together, then, the different values of this constant which 

 have been found at Pulkowa from time to time, we have : 



1. From declination observations of aUrsoB Minoris, 20' / .495:L0".013; 



2. From R. A. observations of polar stars, 20".491 ± 0".009 ; 



3. From observations in the prime vertical, 20".490 ± 0".011 ; 



and, giving the same weight to these three mean values, the definitive 

 value of the constant of aberration is 20".492 ± 0".00G. This must be 

 an extremely accurate value of this important constant, and will prob- 

 ably have to be considered final until it can be corrected by an equally 

 accurate and extensive series of determinations made in the southern 

 hemisphere. Such a determination is at the present time a desideratum 

 in astronomy. In combination with Cornu's determination of the ve- 

 locity of light, the above gives 8".777 for the solar parallax, whilst, if 

 Michelson's determination be adopted, it gives 8".791 ; a striking con- 

 firmation of the value of the solar parallax found by Mr. Gill from his 

 heliometer observation of Mars, made at Ascension, in 1877. — (A. M. 

 Downing, in The Observatory, December, 1883.) 



Professor Peters, of Hamilton College, who is abroad investigating 

 the star catalogue of Ptolemy with a view to an accurate edition, has 

 been fortunate in finding, both at Venice and at Florence, several MSS. 

 (Greek, Arabic, and Latin) of the "Almagest," hitherto not utilized by 

 modern scholars. He is now engaged in a prolonged research in the 

 Vatican library. 



Ihe Fundamental Catalogue of the Berliner Jahrhuch. — A very impor- 

 tant comparison by Dr. Auwers, of the Fundamental Catalogue of the 

 Berliner Jahrhuch with those of the Nautical Almanac, the Connaissance 

 des Temps, and the American Epliemeris appears as a supplement to the 

 Jahrhuch for 1884, and the following abstract of it is given. The year 

 18S3 is the first in which such a comparison is possible. 



The Berliner Jahrhuch contains at present, and will contain for the 

 future, 450 stars whose apparent places are given, and 172 stars for 

 which only mean places are printed, i. e., 622 in all. The places of 

 the^e stars, both in E. A. and Dec, depend strictly on the system of the 

 Fundamental Catalogue of the Astronomuche Gesellsclmft (publ. xiv). 

 They lie between the north polo and — 31°.3 declination. 



The American Epliemeris contains the mean places of 383 stars, for 

 208 of which ephemerides are given ; 44 of these stars lie south of —31°. 

 The Nautical Almanac has 197 stars (15 south of —32°), and ephemer- 

 ides are given for all. The Connaissance des Temps has 310 stars between 

 the north pole and —70°, and gives an ephemeris for each. 



Dr. Auwers^s account of the sources from which the star places of the 

 various almanacs are taken, we omit. It shows how various these are. 

 Four hundred and fifty stars have ephemerides in the Jahrhuch; 149 

 stars (mostly southern) which have ephemerides in the three other 

 almanacs are not contained in the Jahrhuch. 



A table is given in Dr. Auwers's paper, showing the comparison be- 

 • 



