ASTEONOMY. 223 



tain amount of evidence in its favor in past observations, as those of 

 W. Struve and others. The writer has made a series of such obser- 

 vations for three years on the width of the dusky rings, and finds ring 

 C wider on the east side than on the west side by about 0".3. Mr. 

 Mayer's result is 0".5. Otto Struve found (185G) 0".2. While there is 

 a strong probability that such minute difl'erences as these result from 

 real errors in the measures themselves, there is enough i^robability of a 

 difference to make the measures worth a complete discussion. 



OBSERVATORIES. 



The Imperial University of St. Petersburg has founded an observa- 

 tory and placed it under the charge of Dr. Glasenapp. The equipment 

 consists of two refractors, by Merz, of C and 4 inches aperture respect- 

 ively, of portable and field instruments, and of an astronomical clock 

 by Wiren. The director asks for an exchange of publications with 

 other observatories. 



A popular observatory has been established at the Palace of the Tro- 

 cadero, Paris. Founded by M. Leon Jaubert, it has just been opened 

 to the people, and many hundred free tickets have been applied for and 

 received. Each ticket admits its owner to the observatory between 1 

 and 4 o'clock in the afternoon, and from 8.30 to 11 o'clock at night. It 

 allows him to attend the practical school of astronomy, the demonstra- 

 tions on instruments, the literary, the scientific conferences, and the 

 popular laboratories of general physics. 



A new observatory is being built by Columbia College, New York 

 City. It is to be used in connection with the scientific department to 

 instruct engineering students in the use of the portable instruments 

 and equatorial. It is placed in charge of Prof. J. K. Rees, a graduate 

 of the coUege. Proposals are being considered for building a 20-foot 

 dome. According to the Annuaire of Brussels Observatory, for 1881, 

 there are at present 118 public astronomical observatories in full ac- 

 tivity, viz, 84 in Europe, 2 in Asia, 2 in Africa, 3 in Oceanica, and 27 

 in the two Americas. The United States alone have 19, Mexico has 2, 

 Brazil, Chili, Columbia, Ecuador, the Argentine Ecpublic, and New 

 Britain 1 each. In Europe, Prussia is the state which has most public 

 observatories; it has 29; next come England and Russia, which have, 

 respectively, 14 and 12; then Italy, which has 9, Austria 8, France 6, 

 Switzerland 4, Sweden 3, Holland, Norway, Spain, and Portugal, 2 each; 

 lastly, Belgium, Greece, and Denmark. The oldest observatory in oper- 

 ation at present is that of Ley den, founded in 1G32. In America, since 

 1870, six observatories of the best construction and most perfect equip- 

 ment have been established. 



An observatory is to be erected at Hong Kong, at a cost of about 

 $34,000, for the purpose of dropping a time-ball for the shipping and for 

 carrying on magnetic and meteorological observations. From the offi- 

 cial papers we notice that a decided impulse to this motion has been 



