( 209 ) 



to some consideration in those cases, where the observe tiotis cannot 

 as yet furnish the necessary information. Such a case being- before 

 us we are justified in not wholly disregarding what it teaches. 



6. According' both to observation and theory therefore a more or 

 less sudden displacement of the axis of rotation between 1850 and 

 1800 must be regarded as possible and so I think that for the 

 present only observations after that time may be employed to deduce 

 the length of the period. 



In the following table all the epochs of maximum after 1858, that 

 have been determined, are brought together, at least those which were 

 accessible to me and which seemed more or less trustworthy. In the 

 first place all the results of H. G. v. D. S. Bakhuyzen have been 

 inserted, together with those of ^YILT^:RDINK for Leyden ; further 

 several ones deduced by Ciia>:dler, then my result from the obser- 

 vations 1890 — 1896 and finally an epoch of maximum deduced by 

 me from all the observations with the vertical circle at Pulkowa 

 1863 — 1875, as they have been treated by Ivanoff. 



1) CuANDLEli ako discussed these series of observations; his results deviate resp. 

 only + 4, + 5 and — 5 days. 



-) GoNXESSlAT, wliose observations of 15 polar stars have been employed here, found 

 himself an epoch 3 d.iys later. Hull. Astr. Vol. XI. Afterwards a forniuhi with 4 terms 

 has been deduced by him. C. li. T. 124. page 930. 



