176 



ON THE SQUARE BAK MICROMETER. 



Observed Transits. (See article 12.) 



Reduction. 



The above is a convenient form of reduction. Its three lower sections con- 

 tain the determination of the local mean time of observation ; the difference 

 of right ascension, equation (1), corrected for position zero, determined on p. 

 177; and the difference of declination determined by (5), the declination being 

 small. 



