636 KEPOKTS OF ASTRONOMICAL OBSERVATORIES. 



Columbus, FranUin County, Ohio. 

 Private Observatory. 



Longitude from Washington, 23°^ 54^ W. 



Latitude, 40° 0' 1".5 i^. 



Authority for latitude and longitude: Coast Survey for State-house 

 dome, a couple of miles or so distant. 



Director : K. W. McFarland. 

 Instruments : 



(c) Equatorial instrument : makers, Alv an Clark & Sons ; aperture 

 of objective, 5 inches (nearly completed). 



{(j) Clock: mean time; makers, Parkinson & Frodsham. 



Dubuque, loica. 

 Dubuque Observatory. 



Longitude from Washington, 54™ 27s.01 W. 



Latitude, 42° 29' 38" N. 



Authority for latitude and longitude: Boundary line between the 

 States of Illinois and Wisconsin, projected through tbe city of Dubuque; 

 and telegraphic record of star transits at Ann Arbor and Dubuque. 



Director : AsA Horr, M. D. — Under the supervision of Prof. J. C. 

 AYatson, in 1805. 



Instruments : 



(b) Meridian transit instrument: maker, Wm. Wijrdem Ann, Wash- 

 ington, D. C. Aperture, IJ inches; magnifying power suflBcient to note 

 time by stars of the 10th magnitude. Finding circle, 4^ inches diam- 

 eter, reading by verniers and lenses to half a minute of arc. The pier 

 extends 17 feet into the ground, through clay to gravel; it is 7 feet 6 

 inches diameter at base, 3 feet at top, which is 4 feet above the surface ; 

 is surrounded by a brick wall, 8 inches from the stone shaft, the space 

 between (at the surface of the ground) being stufied with oakum. The 

 Y's rest on thin brass supports on the top of stone j)illars, instead of the 

 iron frame which acme with the instrument. 



{g) GlocJc: mean time; makers, Howard »fc Co., Boston. Tower 

 clock, reliable to less than a second a day through all extremes of tem- 

 perature. 



(h) Chronometer : meantiuie; maker, K. Zimmerman, Liverpool, Eng- 

 land. 



Worh: The transit instrument was erected, and has been used almost 

 exclusively for the determination of local time. 



