12*? 



the year 1891 lias been left out of the calcuhxtions, as the transit- 

 circle was not in working order for some months, and the results of 

 the different parts of the year may differ systematically from each other. 



Further, up to 1902 only observations taken with the Transit circle 

 are used, after that also Altazimuth observations, in so far as they 

 were taken in the meridian (which did not occur before 1903) and 

 finally, after 1905 I could also use observations of the crater Moesting A. 



The secular term was computed for every month or two months 

 from a graphical interpolation between the annual means, given in 

 the paper by Prof. Bakhuyzen in These Proc. 14, 691 undei the 

 heading M — NI, after these values] had been diminishedby a 

 28'^^ part for the motion of the moon between the moments of 

 calculated and observed transit ^). 



Finally we come to the corrections to be applied to the observed 

 time of transit of the moon's limb. These depend principally ui)on 



personal errors, and can therefore in the course of years undergo 

 great and irregular variations. On the other hand it is desirable, 

 in order not to be too dependent upon accidental errors, not to 

 determine the corrections for each year separately. 



Taking this into consideration, the errors in observing the limbs 



1) Gorap. These Proc. 14, 9i)2. 



