632 KEPORTS OF ASTRONOMICAL OBSERVATORIES. 



Chicago, Coolc Counti/, IlUnois. 

 Dearborn Observatory. 



Longitude from Wasliingtou, 42'» 14^G9 W. 



Latitude, 41o 50' 1" N. 



Directors : T. H. Saffokd, 1865 ; 

 G. W. Hough, 1S75. 



Anuexed to the University. Founded by subscription in 1822. In 

 1864 it came into possession of an equatorial of 18i inches (0™.47) aper- 

 ture, made by Alvan Clark, with the assistance of which S. ^\\ 

 BURNHAM has made a close and most interesting study of many double 

 stars. 



Instruments : 



{a) Meridian circle: makers, Eepsold & Son; diameter of circle, 40 

 inches; divided to 2'; read by 4 microscopes to O'M; aperture of object- 

 ive, 6 inches ; for observations of the sun, aperture employed, 3 inches. 



(c) Equatorial instrument: makers, Alvan Claek & Sons; aperture 

 of objective, 18^ inches ; magnifying jiowers of cye-j)ieces, positive, 120, 

 190, 287, 385, 900; negative, 135, 225, 450, 900. 



(/) Chronograph: G. W. HoUGH ; cylinder recording. 



{g) Clocks: one mean time; makers, Howard & Co.; Graham escape- 

 ment, mercury pendulum : one sidereal: makers, Charles Gortner & 

 Co., London; Graham escapement, mercury pendulum. 



[h) Chronometer : sidereal; makers. Bond & Son. 



(i) Miscellaneous: signal mean time clock for transmitting time sig- 

 nals. 



Observations during the tast year (from January, 1880, to 

 March 1, 1881): 



(a) Eepsold meridian circle. Observations for " Time." 



(c) Micrometer observations of the satellites of Uranus. Micrometer 

 observations on the planet Jupiter. (1) Great red spot ; longitude, lat- 

 itude, length, breadth, &c. (2) Equatorial white spots ; longitude, lat- 

 itude, length. (3) Miscellaneous spots; longitude, latitude, length. 

 (4) Position and magnitude of the equatorial belt. (5) Position and 

 magnitude of the faint belts. (6) Physical observations. Comet obser- 

 vations for positions. Miscellaneous work. 



Work proposed for the coming year (1881): 



Satellites of Uranus. 



Jupiter continued. 



Miscellaneous. 



Principal publications of the observatory during the 

 Y^EAR 1880: 

 G. W. Hough, Eei)ort of the Director. Pamphlet. 



Satellites of Uranus. Astron. Nachr. 

 Eed spot on Jupiter. Astr. Eegister. 

 Observing seat for the equatorial. Monthly Kotices. 



