ASTRONOMy FOR 1889, 1890. 133 



A remarkable star of the Algol type, having: the shortest period 

 jiiiowii, was discovered in 1888 by Prof. H. M. Paul, of the U. S. Naval 

 Observatory. The star is 12 Autli* of Gould's Urauoiuetria Argeutina, 

 «=9^ 2G™ oO% 3= — 280 4.7 (1875.0). The range of magnitude is 6.7 to 

 7.3, and according to Chandler it goes through its changes in 3'' 20'". 



From an examination of one of the photographic plates taken by the 

 Harvard observatory party, at the Chosica station iu Peru, Professor 

 Pickering has announced the discoverv of a long-period variable iu 

 Caelum of the same class as O Ceti, It Hydrge, and K Leon is. The 

 spectra show bright hydrogen lines. 



A number of other new variables have been detected in the exami- 

 nation of the photographic plates taken at the observatory, and have 

 been announced by Professor Pickering in the Astrouomische Nach- 

 richten. Some attention has also been paid to this subject by Dr. J. C. 

 Kapteyu iu measuring the plates taken at the Cape of Good Hope lor 

 the formation of Dr. Gill's photographic southern Durchmuslerung, aiul 

 also by Mr. Roberts iu the prosecution of his work in astronomical pho- 

 tography. 



A general index to observations of variable stars, prepared under 

 the direction of Prof. E. C. Pickering, forms No. 8 of Vol. 18 of the Har- 

 vard Annals. A large number of unpublished observations are referred 

 to, particularly three extensive series of observations by Argelander, 

 Heis, and Schmidt, to whose manuscripts access was given. 



A new edition or rather revision of Birmingham'' s Red Star Catalogue 

 has been printed in No. v cff the Cunningham Memoirs of the Royal 

 Irish Academy. The work of revision was undertaken by Rev. T. E. 

 Espin in 1886, with the 17^-inch equatorial reflector, and in the course 

 of the work a number of new red stars, new variables, and stars with 

 bright lines iu their spectra were discovered. There is also an addi- 

 tional list of 629 " ruddy stars," 



STELLAR SPECTRA. 



Spectrum of C Ursw Majoris. — Professor Pickering has reported a re- 

 markably interesting peculiarity in the spectrum of this star. It w'as 

 noticed that the Kline was double in the photographs taken March 29, 

 1887, May 17, 1889, and August 27 and 28, 1889, while on many other 

 dates the line ai)peared hazy as if the components were slightly sepa- 

 rated, and at other times the line was well defined and single. It was 

 concluded that the line was double at intervals of 52 days beginning- 

 March 27, 1887, and it was psedicted that the doubling would occur 

 again on December 9, 1889, and this prediction was confirmed by each 

 of three photographs on the latter date. Professor Pickering says : 



"The only satisfactory explanation of this phenomenon as yet pro- 

 posed is that the brighter component of this star is itself a double star 

 having components nearly equal in brightness and too close to have been 

 separated as yet visually. Also that the time of revolution of the sys- 



