OF ARTS AND SCIENCES. 



15 



" Micrometric Measurements of the Differences of Right Ascension of 

 Mercury and the Swn's Limb, corrected for Refraction, and also 

 for the Sun^s Motion in the Intervals of Transit. 



The telescope used was a Refractor of 2|-inch aperture and 46 inches focus, 

 furnished with Troughton's spider-line micrometer. 



* The original record was 22.0 s., but partially altered to this efFect. 

 t Apparently in error 2 s. for 40.6. 



