ASTRONOMY. 195 



final results. Cambridge, England (30-25), is well advanced in reduc- 

 tion. Berlin has two zones; 25-20 is in progress, 20-15 is finished. 

 Leipzig also has two zones; 15-10 is finished, and 10-5 is in progress. 

 Albany (5-1) is far advanced. Mcolajeff (1 to —2) is well under way. 



Parallax of stars. — Professor Ball, Eoyal Astronomer for Ireland, 

 found for the parallax of CI Cygni, as deduced from measures of 61 A 

 Cygni and a small star n. f., 



+0". 4C54±0."0497. 



A second series has been completed in which 01 B Cygni and the 

 small star n. f. were used. Difierences of declinations were measured 

 in both cases. The last result is — 



-f0."4676±0."032L 



That is, the agreement is exact, and Struve's value for the parallax of 

 this system is confirmed rather than Bessel's. 



The search for objects having curious spectra, which has been car- 

 ried on for some months at the Harvard College Observatory, has led 

 to the discovery of another singular star by Prof. E.-C. Pickering. The 

 spectrum consists jirincipally of bright bands, one in the blue being 

 especially marked. Only four objects of this kind have heretofore been 

 known, one of these having been discovered likewise at Cambridge, 

 Mass., last August. This same method of search, which originated 

 last summer at the Harvard College Observatory, has been adojjted at 

 the observatory of the Earl of Crawford and Balcarres, and Dr. Cope- 

 land has already shown that a curious double nebula is gaseous. It 

 will also be introduced in the Eoyal Observatory at the Cape of Good 

 Hope, and there aijplied to extreme southern objects. 



Variable Stars. — "Photometric Measurements of the Variable Stars 

 /? Persei and DM. 81° 25. By Edward C. Pickering, Arthur Searle, 

 and O. C. Wendell," (Proc. Amer. Acad., Vol. XVI, 28 pp.). The pho- 

 tometer used at Harvard College Observatory for the observation of 

 these two variables consists of a double-image prism placed between 

 the object glass and the eyepiece of a small telescope, which ha« a 

 Nicdl prism in front of the eye-piece. By this instrument two ad- 

 jacent stars may be compared with great accuracy, as the two images 

 of each will be formed by the double-image prism, and their relative 

 brightness may be varied by turning the Nicol. Each image in turu 

 will disappear when the Nicol is turned 90°, and there will consequently 

 always be four positions in which tlie brighter image of the fainter 

 star will be precisely equal to the fainter image of the brighter star. 

 i? Persei was compared with the fifth magnitude star w Persei 90' dis-. 

 tant. The two images were formed by two Eochon prisms which pro- 

 duced a separation of about 100', so that they had to be placed very 

 near the object glass of the telescope in order that the images of the two 



