ARTICLE X. 



Astronomical Observations made at Hudson Observatorij, Latitude 41° 14' 40" 

 North, and Longitude 5 A. 25 m. 455. West. By Elias Loomis, Professor of 

 Mathematics and Natural Philosophy in Western Reserve College. Read 

 April 2d and I6th, 1841. 



The instruments of the observatory and the mode of using them have re- 

 mained unchanged since my former paper was communicated to the Society, 

 and the objects observed have been generally the same. The clock has been 

 once stopped. In my former communication I remarked that the pendulum 

 appeared to be over-compensated. This opinion vs^as confirmed by subsequent 

 observations, and on the 31st of January, 1840, 6.2 ounces of mercury were 

 taken from the cistern, leaving the column 6.12 inches in height. Since that 

 time the clock has been constantly running, and its rate has been tolerably 

 satisfactory. 



I. Latitude of Hudson Observatory. 



During the past season I have observed nine culminations of Polaris. The 

 observations were made alternately direct, and, by reflexion from mercury, 

 generally a dozen at each culmination. The three microscopes were invariably 

 read at each observation ; the observations were reduced to the meridian by the 

 usual method, and corrected for refraction by Bessel's tables. The errors of 

 the niicroscopes were found to be as follow : 



North Polar Distance. 



358= 25'— 30' 



A. 



— 2".6 



B. 



+ 0".l 



c. 



+ 0",2 



Mean. 



— 0".77 



279 0—5 



— 2 .2 



— .9 



— 6 .6 



— 3 .23 



VIII. — 2 L 











