( 210 ) 



For tlint purpose I employed liis table on page 269 of the „Re- 

 cherches détiiiitives" and resolved the 14 equations founded there- 

 on without paying' regard to the weights assigned. The epoch 

 obtained by me agrees entirely with the epoch deduced from a 

 curve by Ivanoff himself. 



The column E contains the rotation-numbers of the maxima ; for 

 the initial epoch was taken the mean maximum epoch of my prece- 

 ding paper. The following column contains the epochs of 

 maximum reduced to Greenwich and against these the weights have 

 been inserted which I assigned to those results. It was difficult to 

 determine these weights accurately on account of the evidently con- 

 siderable systematic errors. It was not allowed to take as their 

 exclusive measure the mean errors derived from the agreement of 

 the observations of a single observatory inter se ; so they have been 

 determined according to a rough estimation. I adopted the values 

 assumed by H. G. v. d. S. Baehuyzen, and for the remaining 

 series I acted in an analogous manner. The column Obs. — E. B. I. 

 contains the deviations from my formula deduced in the preceding 

 paper and the last contains the authorities from which the several 

 results were borrowed. 



I at once omitted the series of Greenwich finally not included by 

 H. G. V. D. S. Bakiiuyzen in his computation, their results being 

 already contained in those of the other series. On the other hand 

 I have inserted, besides the epoch deduced from Ivanoff's results 

 for all the observations with the Vertical Circle at Pulkowa 1863 — 

 1875, also those deduced by H. G. v. D. S. Bakhuyzen, from Polaris 

 only, as observed resp. by Gyldén and Nyrén. True, the former 

 result is founded on a much greater number of observations, but it is pos- 

 sible that the mixing up of the results of both observers has done 

 more or less harm, a point which Ivanoff himself also discusses 

 in his first paper page 516. 



I have now tried to correct my first formula with the aid of the 

 results compiled in this way, and have rigorously resolved for that 

 purpose all the equations they furnished, having due regard to their 

 weights. At first sight the differences Obs — E.B.I seem to betray a 

 non-linear course, but on closer examination this proves to be only 

 apparent, at least for the greater part, and on account of the occasio- 

 nally considerable differences between close-lying epochs I thought 

 I was not allowed to depart even now from the simple supposition 

 of a constant length of the period. I made two solutions: including 

 the first time the result accordin»- to Ivanof and omitting those of 



