OF ARTS AND SCIENCES. 



165 



In Tables XII., XIII., and XIV. will be found the corrections necessary to 

 reduce the observations made at different observatories to a homogeneous 

 system. 



Let 



C = the correction to be applied to the observations. 



Then 



C ^ e + (m sin a + n cos a) + {m' sin 2 a + n' cos 2 a) + (a sin 6 + 6 cos 6). 



Thus for Edinburgh, when a = Q^ and 6 = — 20° : — 



C = +.036 —.013 +.002 +.046 = +.071. 



TABLE XII. 

 Tabular Corrections for Errors of Single Period. 



