380 SCIENTIPIC RECORD FOR 1883. 



errors, and it is evident that this is far more likely to be the case with 

 meridian observations than with the micrometer measures. The value 

 of the semi-axis in the direction of the declination circle, found by M. 

 Strove, satisfies all the observations used by Auwers within the limits 

 of errors of observation, while on the other hand the Pulkowa microme- 

 ter measures clearly indicate a correction to Auwers' value. As M. 

 Wagner's observations do not prove the necessity of altering the adopted 

 value of the semi-axis in the direction of the parallel, we are led to the 

 conclusion that the apparent orbit of Procyon is an ellipse, the semi-axis 

 major of which, parallel to the equator, is 0" 979, while the semi-axis 

 minor is 0"G98, The real orbit must therefore be a circle, perpendicu- 

 lar to the declination plane and forming an angle of 45J° with the line 

 of sight. — (Copernicus, November 31, 1883.) 



Spectroscopic survey of the northern heavens. — Such a survey has been 

 begun at the Astrophy sical Observatory at Potsdam, the first thoroughly 

 systematic work of the kind since Secchi, and after him P/ Arrest, spec- 

 troscopically examined a large number of fixed stars. Professor Vogel 

 intends to prepare a complete spectroscopic star catalogue, and a good 

 portion of the work has already been accomplished. To prepare such 

 a catalogue, says Vogel, is a duty which the present generation owes to 

 posterity. The changes taking place in the stars are of especial interest 

 to us and are of importance to science ; and although it may be con- 

 jectured that changes in the spectra will show themselves soonest in 

 those stars which have proceeded farther in their development, that is, 

 in the red stars, yet this cannot be posith*ely affirmed a priori. Equally 

 with those wonderful spectra of the red stars, which so enchant the 

 eye of the observer, will changes take place in the course of time in the 

 simple spectra ol the white and yellow stars, so that investigations of 

 as large a number of star-spectra as possible, without limiting them to 

 particular classes of stars, are absolutely necessary for future researches. 



Dr. Dun6r, in Lund, has contemporaneously begun, on the same plan, 

 the observation of stars round the North Pole, so that the work is begun 

 on two sides. 



Professor Vogel has published part of his investigations — the zone 

 between — 1° and 4-20° declination; the second part, from 4-20° to 

 +40°, will quickly follow. The stars have been completely surveyed 

 down to the magnitude 7£, and a large number of smaller ones were 

 examined along with them ; altogether they number nearly 12,000, 

 and on an average 3 stars were found in a field of view 19' in diameter, 

 which were examined together. 



Vogel has, as is known, arranged all the stars spectroscopically in 

 three chief divisions, of which the first is again subdivided into three 

 and the others into two subdivisions. Of these, no stars belonging to 

 Glass Ic (in which the hydrogen line and the line D appear bright) nor 

 to 116 (in which, besides dark lines and bands, several bright lines also 

 appear) are found in the published zone. 



