XX GENERAL SUMMARY OF SCIENTIFIC AND 



A complete catalogue of all double stars hitherto observed 

 as such has been promised as a posthumous work of the late 

 ISir John Ilerschel. Meanwhile an equally complete cata- 

 logue has been pre])ared for publication by Mr. Burnham, of 

 Chicago. Either of these works will evidently correspond to 

 a lono-reco^nized need of the astronomers at work in this field. 



In the line of new discovery, it is probable that the event 

 lirst in the order of interest is the discovery of a companion 

 to Procyon, made in March last by Struve at Poulkova. The 

 interest attaching to this discovery arises from the probabil- 

 ity that the newly found companion is the satellite which 

 gives a minute circular movement to the bright star. This 

 motion has been very clearly indicated by observations made 

 during the last hundred years or more, the researches of Dr. 

 Auwers showing the period of revolution to be about forty 

 years ; but the satellite whose attraction was supposed to 

 cause the motion had never been found. More observations 

 Avill have to be made on the satellite found by Struve before 

 it can be certainly decided whether it is really the disturbing 

 body, and it may be hoped that these will be speedily fur- 

 nished by the great Washington telescope. 



In the planetary system, we note the determination of the 

 mass of Jupiter by Krilger, who bases his computation upon 

 the perturbation of the asteroid Themis ; the publication by 

 the Smithsonian Institution of Newcomb's tables of Uranus; 

 the publication by Hirn of a masterly disquisition on the 

 theory of the rings of Saturn ; the numerous investigations, 

 especially those of Klinkerfues, on Biela's comet, and its con- 

 nection with the meteoric train and with Pogson's comet; 

 the investigjations of Von Asten in reference to a new method 

 of computing the perturbations of Encke's comet, have a di- 

 rect bearing upon the question of the existence of a resisting 

 medium in space. 



The phenomena of nutation and precession have been in- 

 vestigated by Dr. Nyren, whose results, deduced from the 

 observations made by the elder Struve with the prime ver- 

 tical transit, do not differ materially from those of C II. F. 

 Peters. The existence of a periodical change in the latitudes 

 of points on the earth's surface seems liighly ])robable. 



A highly valuable discovery has been made of a manu- 

 scri[)t by Schroter, of a volume of at least two hundred pages 



