40 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



Arthur Searle, A.M., Assistant. 



Leonard Waldo, A.M.. Assistant, in charge of the time-service. 



Winslow Upton, A.M.; employed in work undertaken in aid of 

 the CoaBl Burvey, and in Equatorial observations. 



Miss R. < ; . Bannders; employed in reductions of the observations 

 made with the Meridian Circle. 



Mr. Joseph F. McCormack ; employed in assisting in the observa- 

 tions made with the Meridian Circle, and in reducing them. 



Mr. C. II. Met calf; employed in reductions of photometric work. 



There arc other persons not immediately connected with the 

 observatory who are customarily employed in performing computa- 

 tions for it. 



Second. The principal instruments of the observatory are: 



The East Equatorial, a refractor of 15 inches aperture and 22 

 feet focal length, made by Merz, of Munich, and mounted in 1847. 



The West Equatorial, a refractor of 5 inches aperture and 7 feet 

 focal length, made by Alvan Clark and Sons, and mounted in 1869. 



The East Transit Circle, made by Troughton and Simms, and 

 mounted in 18-48. Aperture of telescope, 4J inches; focal length, 



5 feet. 



The Meridian Circle. The object-glasses of the instrument and of 

 its collimators were made by Alvan Clark and Sons; the metal 

 work mainly by Troughton and Simms. The instrument was largely 

 designed by the late director of the observatory, Professor Joseph 

 Winlock, and has done great credit to his ingenuity. The aperture 

 of the principal telescope is 8 inches, and its focal length 9 feet 4.4 

 inches. The aperture of each collimator is 8 inches, and its focal 

 length the same as that of the chief telescope. The instrument was 

 mounted in 1870. 



The Portalle Transit Instrument, made by Herbst, of Pulkova, 

 and mounted in 1870. Aperture of telescope, 2f inches ; focal length, 

 33 inches. 



Third. The subjects of observation to which attention has been 

 devoted during the past year may be classified with regard to the 

 instruments employed in investigating them. 



The work done with the Equatorials has been principally pho- 

 tomet lie The objects observed have been the satellites of the supe- 

 rior planets (including those of Mars), some of the asteroids, and 

 -Mine of the fixed stars. Mars and Saturn, and also Jupiter andl tvjws, 

 have been compared with each other. 



Micrometrie measures have been made, chiefly of Mars and of its 

 satellites. 



The Meridian Circle has been employed, first, in observing the 

 zone 50 to 55 north declination, undertaken by this observatory as 

 ii contribution to the work of determining the places of the stars 



