ERRATA. 



Page 44, line 14 from above: For "in front of the special treatment of the separate perturbations", read 

 "at the end of this volume". 



59 : As the table shows, e, is not determined for Wilhelmshaven. By comparing the vertical curves 

 with those from Potsdam, we found by deduction that e, = 10 y per mm. might not be so far 

 from the right value. This value has been used in the calculations. On a later inquiry at the obser- 

 vatory, we obtained the value E V = 20 y per mm., but it was rather uncertain. This value, how- 

 ever, we have not made use of, for in what we had to consider it was the direction of the 

 vertical component and its variation that were of the most importance, and not the actual amount 

 of P,. 



67, line i from below: For "Chap. Ill", read "Part II, Chap. I". 



68208, On the Charts, for "V v ", read "/>". 



70, line 12 from below: For "negative", read "positive". 



71, lines 12 & 13 from above: For "must be of a somewhat local character", read "must belong to 



another system". 



96, ,, 7 & 6 below : After "positive vortices" add "of the negative rays". 



96, 6 & 5 For "divergence", read "convergence", and vice versa. 



121, Table XVIII, Zi-ka-wei, P, line 14: For "5.83 X 10 /', read "5.8 y". 



128, line 3 from below: For "Chapter III", read "Part II, Chapter I". 



198, Table XXX, Christchurch, P, line i: For "1.5 y", read "+i.sy". 



